Respiration 3-J: 186-191 (1977)
Comparison of the Effects of Several Selective B2-Receptor Agonists on Bronchomotor Function in vitro J. Iravani and G. Norris Melville Silikose-Forschungsinstitut (Chefarzt: Prof. IV. T. Ulmer), and Lehrstuhl für Anatomie II. Ruhr-Universität Bochum (Direktor: Prof. K. H. Andres). Bochum
Key Words. Bronchomotor function ■B,-Adrenergic stimulants Abstract. Three selective B,-adrenergic stimulants were studied for their effect on the
Every clinician is cognisant of the effect of the sympathomimetic amines on the bronchial smooth muscle in patients with obstructive airway disease. These substances owe their success to their ability to act almost exclusively on B-receptors by virtue of their N-alkyl substitution. The uncontrollable side effects of drugs such as isoproterenol, that is, buccal ulceration after sublingual adminis tration, tachycardia, arrhythmia [Kiindig, 1972] have prompted a search for drugs that act selectively on the bronchial smooth mus cle. This group of substances are purported to have a greater affinity for the B,-receptors
of the bronchi than for the B,-receptors of the heart. Iravani and Melville [1975] in a study of the effectiveness of isoproterenol and its isomer metaproterenol on reversing the ACh-induced bronchoconstriction found that neither of the two substances was effec tive unless a-reccptor sites were blocked by phentolamine. In other studies on the effect of a new selective B,-mimetic substance (NAB 365) [Iravani and Melville. 1974] it was observed that the resting bronchial tone was diminished, a situation which up to now had never been seen with other B;-mimetic
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resting tone and on reversing acetylcholine(ACh)-induced bronchoconstriction in the intrapulmonary airways of rats in vitro. Neither l-(3,5-dihydroxyphenyl)-2-[( l-[4-hydroxybenzyl]-ethyl)-amino]-ethanol-hydrobromide (Fenoterol) nor 2-tert-butylamino-l -(3,5-dihydroxyphenyl)-ethanol-sulphate (Terbutaline) had an effect on the resting tone. 4-Amino3.5-dichlor-«-[(tert-buty!amino)-methyI]-benzylalcohol-hydrochloride (NAB 365) caused a significant increase in the bronchial luminal diameter from control in the resting state at concentrations above 10-5g/ml. Only NAB 365 was effective in reversing ACh-induced bronchoconstriction in concentrations above l(H g/m l. Terbutaline and Fenoterol reversed the ACh-induced bronchoconstriction only after the «-receptors had been blocked by phentolamine (10-5-10-4 g/ml).
187
Iravani/Melville
10~5
10'6
to"4
g/ml
ACh + Terbutaline + NAB 365
Fig. I. Percentage changes in the resting bronchial tone after NAB 365 (■ ). Fenoterol ( • ) and Terbuta line (T ) at varying concentrations. Values are the means.
Fig. 2. Effects of Terbutaline on reversing the ACh-induced bronchoconstriction in rats. NAB 365 (10 4 g/ml) was administered after the final effective concentration of Terbutaline. Values are the means.
Table I. Effect of Terbutaline on reversing ACh-induced bronchoconstriction (values are the percentage change from control ± SEM )
the resting bronchial tone and on ACh-in duced bronchoconstriction.
Rat No. ACh 10'"
NAB 365
Terbutaline
Methods 10'"
10~s
10J
35
- 36.0 - 36.0 - 28.0
- 36.0 - 36.0 - 17.0
- 33.0 - 3 1 .0 - 28.0
- 33.0 - 36.0 - 22.0
- 22.0 - 16.0 0
49
- 33.0 - 35.0 - 40.0
- 33.0 - 35.0 - 40.0
- 33.0 - 35.0 - 40.0
- 33.0 - 27.0 - 40.0
-
50
-
- 55.0 - 38.0 - 5 6 .0 - 36.0 5.8
-
-
- 25.0 0 - 25.0 - 10.5 3.6
Mean ± SE
55.0 38.0 56.0 40.0 2.5
55.0 38.0 56.0 36.5 5.4
55.0 38.0 56.0 36.0 5.2
7.0 0 0
Concentrations are in g/ml.
substances. The latter finding forced us to investigate the effect of NAB 365 and two relatively new selective B2-mimetic drugs on
The experiments were carried out in Wistar rats of both sexes weighing between 220 and 400 g. Following anaesthetisation with sodium phénobarbital (40 mg kg body weight i.p.) the trachea and lungs were excised and dissected as previously described [ Iravani, 1967). Mea surement of the luminal diameter in the intrapulmonary airways was carried out after the method of Iravani and Schiiier (1971). Following control measurements of the luminal di ameter. one of the drugs to be tested was applied into the incubating Krebs solution \ Krebs ami Henseleil, 1932] and measurements were repeated after 15 min. Several concentrations of the same drug were tested in the same airway preparation. In another series of experiments following the control measurements of luminal diame ter. ACh in a concentration of l(H ‘ g/ml was added to the incubating medium and the luminal diameter was measured 10 min later. One of the B2-mimetic drugs was applied into the bath containing ACh and the lu minal diameter was again measured after 15 min. The
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to"7
188
Iravani/Melville
Fig. 3. Effects of Fenoterol on reversing ACh-induced bronchoconstriction before and after a-receptor blockade with phentolamine (10-5- l ( H g/ml). NAB 365 was administered after the highest concentration of phentolamine. Values are the means.
Table II. Effect of Fenoterol on reversing ACh-induced bronchoconstriction in the intrapulmonary airways of rats (values are the percentage change from control ± SEM) ACh 1(T6
Fenoterol
Phentolaminc
lO '6
10'*
10~4
NAB 365 10-4
10‘ *
10"4
36
- 17.0 - 30.0
- 17.0 -3 0 .0
- 17.0 - 3 0 .0
- 17.0 - 30.0
37
- 9.0 - 3 6 .0 - 4 7 .0
- 6.0 - 3 6 .0 -3 8 .0
- 6.0 - 20.0 - 38.0
0 - 20.0 - 38.0
38
- 27.0 - 4 8 .0 - 20.0
- 2 7 .0 - 50.0 - 27.0
- 2 7 .0 - 4 8 .0 - 20.0
- 2 7 .0 - 5 8 .0 - 20.0
51
- 2 5 .0 - 33.0 - 33.0 - 10.0
- 33.0 - 5 0 .0 - 3 3 .0 - 30.0
- 2 5 .0 - 2 7 .0 - 2 7 .0 - 10.0
- 25.0 - 27.0 - 7.0 0
- 25.0 - 17.0 0 10.0
- 16.0 0 + 13.0 + 30.0
0 + 17.0 + 27.0
52
- 30.0 0 - 3 3 .0 - 10.0
- 4 4 .0 - 4 0 .0 - 40.0 - 30.0
- 4 0 .0 0 -3 3 .0 - 20.0
- 3 8 .0 0 - 27.0 - 10.0
- 33.0 10.0 - 13.0 20.0
+ + +
22.0 25.0 7.0 20.0
+ 11.0 + 25.0 + 20.0
53
- 22.0 - 2 5 .0 0 - 3 3 .0
- 4 4 .0 - 50.0 - 20.0 - 4 2 .0
- 33.0 - 4 0 .0 0 - 25.0
- 33.0 - 40.0 0 - 25.0
- 22.0 - 15.0 0 - 17.0
- 22.0 + 10.0 + 20.0 0
+ 22.0 + 25.0
Mean ± SE
- 26.0 2.2
- 3 4 .0 2.8
- 24.0 2.9
- 22.0 3.5
-
+ 5.0 4.9
+ 18.0 3.3
Concentrations are in g/ml.
9.0 4.7
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Rat No.
Selective Bi-Agonists and Bronchomotor Function
•/.
189
Table III. Effect of NAB 365 on reversing AC'h-induced bronchoconstriction in the airways of rats (values are the percentage change from control ± SEM) Rat No. ACh It) "
Results
The effect of Fenoterol, Terbutaline and NAB 365 on the resting bronchial tone is shown in figure 1. Neither Fenoterol nor Terbutaline in concentrations ranging from lO-o to 1(H g/ml had an effect on the resting bronchial tone. NAB 365 in concentrations of 10-hg/mi caused an apparent increase in airway luminal diameter in the resting state; at 10-5 and 10-J g/ml, the increase in bronchial luminal diameter was significant (p < 0.05).
10*s
- 2 3 .0
- 3 9 .0
- 19.0
- 17.0 - 4 3 .0 - 25.0
- 15.0 - 2 1 .0 - 20.0
- 31.0
6
- 8.0 - 3 6 .0 - 30.0
8
- 4 0 .0 - 12.0
- 30.0 - 12.0
- 2 0 .0 - 8.0
- 20.0 - 5.0
9
- 14.0 - 17.0
- 10.0 - 17.0
- 6.0 - 10.0
-
33
- 13.0 - 9.0 - 11.0
- 10.0 + 9.0 0
0 + 11.0 + 14.0
+ 5.0 + 18.0 + 20.0
34
-
29.0 30.0 33.0 48.0 35.0
- 26.0 - 2 5 .0 - 29.0 - 30.0 - 2 0 .0
- 2 1 .0 - 25.0 - 2 1 .0 - 20.0 - 8.0
0 + 8.3 + 4.0 - 5.0 + 13.0
39
- 2 6 .0 - 3 0 .0 - 16.0
- 25.0 - 15.0 - 10.0
- 19.0 0 0
- 19.0 0 0
+ 6.0 + 15.0 + 17.0
40
- 29.0 - 38.0
- 23.0 - 20.0
- 14.0 - 15.0
- 7.0 - 15.0
0 - 13.0
43
- 33.0 - 33.0 - 11.0
- 27.0 - 2 2 .0 0
- 2 0 .0 - 2 2 .0 + 11.0
- 9.0 - 11.0 + 22.0
0 - 11.0 + 44.0
44a
- 30.0 - 37.0 - 10.0
- 28.0 - 30.0 0
- 20.0 0 + 43.0
0 0 + 52.0
+ 10.0 + 14.0 + 73.0
Mean ± SE
- 25.0 2.4
- 17.5 2.3
- 10.5 3.4
+ 2.5 6.3
+ 3.0 4.7
6.0 7.0
Concentrations are in g/ml.
Following administration of ACh (K H g/ ml) the airways contracted as a rule by about 25-40% from the control diameter. Terbu taline in concentrations of up to 10-' g/ml
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reversal effect of several concentrations were tested. In preparations that failed to achieve control values after the highest concentration of the drug was applied, cither phentolamine (10_s—10~4 g/ml) or NAB 365 ( 10-5— 10“* g/ml) was then added to the incubating medium and the luminal diameter again measured after 15 min. The following drugs were used: 4-amino-3,5dichlor-a-[(tert-butylamino)-methyl|benzyIalcohol-hydrochloride (NAB 365: Dr. Karl Thomae, Bibcrach); l-(3.5-dihydroxyphcnyl)-2-[( l-[4-hydroxybenzyl]-cthyl)-amino]-ethanol-hydrobromide (Fcnoterol; Boehringer. Ingelheim am Rhein): 2-tcrt-butylamino-l(3,5-dihydroxyphenyl)-ethanol-sulfate (Terbutaline; Astra Chemicals. Wedel/Holstein). and phentolamine hydrochloride (Ciba. Basel).
5 x 10" s 10-i
lO '6 4
ACh + NAB 365
Fig. 4. Reversal effects of NAB 365 on ACh-induced bronchoconstriction in rats. Values are the means.
NAB 365
190
Iravani/Melville
Of the selective B;-mimetics studied, only NAB 365 had an effect on the resting bronchial tone. It could be argued that the airways were not tonically constricted in the resting state to allow for an effect of Feno terol or Terbutaline. This is ruled out by the fact that longitudinal folds, a sign of contrac tion [Iravani et al., 1975], were present in all airways. It has been suggested that airway patency is maintained by a balance between the a- and /3-adrenoceptors and that over activity of the a-receptors or a decreased /?reserve produce clinical exacerbation and bronchoconstriction [MacDonald et at., 1967; Richardson and Sterling, 1969; 57monssonetal., 1969]. Administration of phentolamine alone does not cause bronchodilation but in the presence of a B-adrenergic substance bron chodilation results [Iravani and Melville, 1975 ]. The reason why of all the B,-mimetics only NAB 365 had an effect on both the resting tone and on ACh-induced broncho constriction in the absence of phentolamine is not clear. It is possible that Fenoterol and Terbutaline have in addition to their B2effect, a stimulating effect on the a-receptors which would then nullify or diminish the Discussion expected bronchodilatory effect. The method adopted in this study [/ra B;-Receptors are confined exclusively to vani and Schuler, 1971] allows the study of the smooth muscle of the airways, thus ad bronchomotor function in locally defined ministration of a substance such as acetylcho areas of the tracheobronchial tree. The mus line that affects mainly the contractile ele cle coat as well as the mucociliary apparatus ments in smooth muscle, is a valuable are intact and remain functional for up to method of testing the effectiveness of any 10 h. selective B2-drugs. Although both Fenoterol The factors that modify the bronchomo and Terbutaline have been shown to reduce tor response were pointed out by Iravaniand airway resistance in vivo [Plit et al., 1972; Scinder [1971] and include the avoidance of Benjamin, 1972; Simonsson et al., 1972; blood aspiration or the development of oede Chaieb et al., 1974], in the present study ma and the length of the hypoxic period after neither of the two had an effect on the AChinduced bronchoconstriction unless the asacrificing the animal.
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was ineffective in reversing the ACh-induced bronchoconstriction (fig. 2). After adminis tration of either phentolamine (KM g/ml) or NAB 365 (10 4 g/ml) there was a significant reversal of the ACh-induced response at the 5 and 1% level, respectively (table I). Fenoterol, similarly, was ineffective in reversing the ACh-induced bronchocon striction until the a-receptor sites were blocked by phentolamine, in which case con trol values were achieved at a phentolamine concentration of 10 4 g/ml (fig. 3; table II). In the presence of ACh, Fenoterol and phen tolamine, administration of NAB 365 caused a greater increase in luminal diameter than that obtained with phentolamine (10 4 g/ml). NAB 365 caused a significant reduction of the ACh-induced bronchoconstriction at concentrations above KM g/ml (p < 0.01 ) (table III; fig. 4). In three airways an increased broncho constriction was seen at a NAB 365 concen tration of KM g/ml (table III) and is proba bly due to a mild a-receptor stimulating ef fect in these airways.
Selective Bi-Agonists ami Bronchomotor Function
References Benjamin. C.: The effect of Fenoterol (Berotec) in mine workers with obstructive airway diseases. Med. Proc. IS: 61 (1972). Constantine. H.: Dautrebande. I..; Kaltreider, N.: I.ovejoy, F. W.; Morrow. P.,and Perkins. P.: Influence of carbachol and of fine dust aerosols upon the breathing mechanics and the lung volumes of normal subjects and of patients with chronic respiratory disease before and after administration of sympathicomintetic aerosols. Archs int. Pharmacodyn. Ther. 123:239 (1959). Chaieb. J. A.: Kamburoff. P. L..and Prime, F. J.: Effect of a repeated dose of tcrbutaline by inhalation. Curr. tried. Res. Opinion 2:275 (1974). Gordonoff, T. und Scheinfinkei, N.: Über die Bronchial peristaltik. Klin. Wschr. 16: 167(1937). Hawkins. D. F. and Schild, H. O.: The action of drugs on isolated human bronchial chains. Br. J. Pharmac. Chemother. 6:682 (195 I ). Iravani. J.: Flimmerbewegung in den intrapulmonalen Luftwegen der Ratte. Pflügers Arch. ges. Physiol. 297:221 (1967). Iravani. J. und Melville. G. N.: Wirkung von Bromhexin-Metabolit VIII und einem neuen adrenergen Stoff auf die mukoziliäre Funktion des Respirations traktes. Arzneimittel-Forsch. 2 4:849 (1974). Iravani. J. and Melville. G. N.: Evidence for alpha and beta receptors in the bronchial tree of rats (in prepa ration, 1975). Iravani. J.: Melville. G. N.. and Richter. H. G.: Closing and opening pressures in the intrapulmonary airways of rats. Pneumonologic (submitted for publ.. 1975). Iravani. J. und Schiiler. K. G.: In vitro Untersuchungen der Bronehomotorik der Ratte. Pneumonologie 144 : 253 (1971 ). Kilburn. K. H.: Dimensional responses of bronchi in apneic dogs to airway pressure, gases and drugs. J. appl. Physiol. / 5 ; 229(I960). Konzett. H. und Rössler. R.: Versuchsanordnungen zu Untersuchungen an der Bronchialmuskulatur. Naunyn-Schmiedebergs Arch. exp. Path. Pharmak. 195.1 \ (1940).
Krebs, H. A. und Henseleit, K.: Untersuchungen über die Harnstoffbildung im Tierkörper. Hoppe-Seyler's Z. physiol. Chem. 209:33 ( 1932). Kündig. H.: Preliminary pharmacological and toxicolog ical studies in the baboon (Papio ursinus) on a new Bi-adrencrgicstimulant, Feneterol (Berotec). Med. Proc.S. Afr. /AV9( 1972). MacDonald. A. G.; Ingram. C. G.. and McNeill. R. S.: The effect of propranolol on airway resistance. Br. J. Anaest. 39:919 (1967). Nadel, J. and Clarke. S. WC A new technique for study ing airway deposition, morphology and mechanism using powdered tantalum. Proc. 3rd Int. Symp. on Inhaled Particles, London 1970. pp. 16-23. Plit. M.: Goldman. H. L. and Cassel. M. L.: The bronchodilator action of Feneterol (Berotec) in asthma. Med. Proc. IS: 41 (1972). Radford. E. P. and Lefcoe, N. M.: Effects of bronchoconstriction on elastic properties of excised lungs and trachea. Am. J. Physiol. ISO: 479 (1955). Richardson. P. S. and Sterling, G. M.: Effects of betaadrenergic receptor blockade on airway conduct ance and lung volume in normal and asthmatic sub jects. Br. mcd. J. Hi: 143 (1969). Simonsson. B. G.: Andersson, R.; Bergh, N. P.; Skoogh, B. E.. and Svcdmyr. N.: In vivo and in vitro studies of pharmacological effects on different receptors regu lating bronchial tone in man. Bronchitis III. Proc. of the 3rd Int. Symp. on Bronchitis at Groningen, Netherlands 1969. Simonsson, B. G.; Stiksa, J., and Strom. B.: Double blind trials with increasing doses of salbutamol and tcrbutaline aerosols in patients with reversible air ways obstruction. Acta med. scand. 192:371 (1972). Trendelenburg. P.: Physiologische und pharmakolo gische Untersuchungen an der isolierten Bronchial muskulatur. Arch. exp. Path. Pharmak. 69: 79 (1912). Wiek. H.. Uber die Wirkung der Kohlensäure auf das Trachealpräparat des Hundes. Archs int. Pharmaco dyn. Ther. SS:450(1952).
Received: December 18. 1975 Accepted: February 2. 1976 Dr. G. Norris Melville, Lehrstuhl für Anatomie II. Ruhr-LIniversität Bochum. Universitätsstrasse 150, MA 6/148, D—4630 Bochum (FRG)
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receptors were blocked, thereby confirming earlier findings [Iravani and Schüler, 1971; Ira vani and Melville, 1974).
191
Comparison of the Effects of Several Selective B2-Receptor Agonists on Bronchomotor Function in vitro J. Iravani and G. Norris Melville Silikose-Forschungsinstitut (Chefarzt: Prof. IV. T. Ulmer), and Lehrstuhl für Anatomie II. Ruhr-Universität Bochum (Direktor: Prof. K. H. Andres). Bochum
Key Words. Bronchomotor function ■B,-Adrenergic stimulants Abstract. Three selective B,-adrenergic stimulants were studied for their effect on the
Every clinician is cognisant of the effect of the sympathomimetic amines on the bronchial smooth muscle in patients with obstructive airway disease. These substances owe their success to their ability to act almost exclusively on B-receptors by virtue of their N-alkyl substitution. The uncontrollable side effects of drugs such as isoproterenol, that is, buccal ulceration after sublingual adminis tration, tachycardia, arrhythmia [Kiindig, 1972] have prompted a search for drugs that act selectively on the bronchial smooth mus cle. This group of substances are purported to have a greater affinity for the B,-receptors
of the bronchi than for the B,-receptors of the heart. Iravani and Melville [1975] in a study of the effectiveness of isoproterenol and its isomer metaproterenol on reversing the ACh-induced bronchoconstriction found that neither of the two substances was effec tive unless a-reccptor sites were blocked by phentolamine. In other studies on the effect of a new selective B,-mimetic substance (NAB 365) [Iravani and Melville. 1974] it was observed that the resting bronchial tone was diminished, a situation which up to now had never been seen with other B;-mimetic
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 1/1/2019 6:09:34 PM
resting tone and on reversing acetylcholine(ACh)-induced bronchoconstriction in the intrapulmonary airways of rats in vitro. Neither l-(3,5-dihydroxyphenyl)-2-[( l-[4-hydroxybenzyl]-ethyl)-amino]-ethanol-hydrobromide (Fenoterol) nor 2-tert-butylamino-l -(3,5-dihydroxyphenyl)-ethanol-sulphate (Terbutaline) had an effect on the resting tone. 4-Amino3.5-dichlor-«-[(tert-buty!amino)-methyI]-benzylalcohol-hydrochloride (NAB 365) caused a significant increase in the bronchial luminal diameter from control in the resting state at concentrations above 10-5g/ml. Only NAB 365 was effective in reversing ACh-induced bronchoconstriction in concentrations above l(H g/m l. Terbutaline and Fenoterol reversed the ACh-induced bronchoconstriction only after the «-receptors had been blocked by phentolamine (10-5-10-4 g/ml).
187
Iravani/Melville
10~5
10'6
to"4
g/ml
ACh + Terbutaline + NAB 365
Fig. I. Percentage changes in the resting bronchial tone after NAB 365 (■ ). Fenoterol ( • ) and Terbuta line (T ) at varying concentrations. Values are the means.
Fig. 2. Effects of Terbutaline on reversing the ACh-induced bronchoconstriction in rats. NAB 365 (10 4 g/ml) was administered after the final effective concentration of Terbutaline. Values are the means.
Table I. Effect of Terbutaline on reversing ACh-induced bronchoconstriction (values are the percentage change from control ± SEM )
the resting bronchial tone and on ACh-in duced bronchoconstriction.
Rat No. ACh 10'"
NAB 365
Terbutaline
Methods 10'"
10~s
10J
35
- 36.0 - 36.0 - 28.0
- 36.0 - 36.0 - 17.0
- 33.0 - 3 1 .0 - 28.0
- 33.0 - 36.0 - 22.0
- 22.0 - 16.0 0
49
- 33.0 - 35.0 - 40.0
- 33.0 - 35.0 - 40.0
- 33.0 - 35.0 - 40.0
- 33.0 - 27.0 - 40.0
-
50
-
- 55.0 - 38.0 - 5 6 .0 - 36.0 5.8
-
-
- 25.0 0 - 25.0 - 10.5 3.6
Mean ± SE
55.0 38.0 56.0 40.0 2.5
55.0 38.0 56.0 36.5 5.4
55.0 38.0 56.0 36.0 5.2
7.0 0 0
Concentrations are in g/ml.
substances. The latter finding forced us to investigate the effect of NAB 365 and two relatively new selective B2-mimetic drugs on
The experiments were carried out in Wistar rats of both sexes weighing between 220 and 400 g. Following anaesthetisation with sodium phénobarbital (40 mg kg body weight i.p.) the trachea and lungs were excised and dissected as previously described [ Iravani, 1967). Mea surement of the luminal diameter in the intrapulmonary airways was carried out after the method of Iravani and Schiiier (1971). Following control measurements of the luminal di ameter. one of the drugs to be tested was applied into the incubating Krebs solution \ Krebs ami Henseleil, 1932] and measurements were repeated after 15 min. Several concentrations of the same drug were tested in the same airway preparation. In another series of experiments following the control measurements of luminal diame ter. ACh in a concentration of l(H ‘ g/ml was added to the incubating medium and the luminal diameter was measured 10 min later. One of the B2-mimetic drugs was applied into the bath containing ACh and the lu minal diameter was again measured after 15 min. The
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 1/1/2019 6:09:34 PM
to"7
188
Iravani/Melville
Fig. 3. Effects of Fenoterol on reversing ACh-induced bronchoconstriction before and after a-receptor blockade with phentolamine (10-5- l ( H g/ml). NAB 365 was administered after the highest concentration of phentolamine. Values are the means.
Table II. Effect of Fenoterol on reversing ACh-induced bronchoconstriction in the intrapulmonary airways of rats (values are the percentage change from control ± SEM) ACh 1(T6
Fenoterol
Phentolaminc
lO '6
10'*
10~4
NAB 365 10-4
10‘ *
10"4
36
- 17.0 - 30.0
- 17.0 -3 0 .0
- 17.0 - 3 0 .0
- 17.0 - 30.0
37
- 9.0 - 3 6 .0 - 4 7 .0
- 6.0 - 3 6 .0 -3 8 .0
- 6.0 - 20.0 - 38.0
0 - 20.0 - 38.0
38
- 27.0 - 4 8 .0 - 20.0
- 2 7 .0 - 50.0 - 27.0
- 2 7 .0 - 4 8 .0 - 20.0
- 2 7 .0 - 5 8 .0 - 20.0
51
- 2 5 .0 - 33.0 - 33.0 - 10.0
- 33.0 - 5 0 .0 - 3 3 .0 - 30.0
- 2 5 .0 - 2 7 .0 - 2 7 .0 - 10.0
- 25.0 - 27.0 - 7.0 0
- 25.0 - 17.0 0 10.0
- 16.0 0 + 13.0 + 30.0
0 + 17.0 + 27.0
52
- 30.0 0 - 3 3 .0 - 10.0
- 4 4 .0 - 4 0 .0 - 40.0 - 30.0
- 4 0 .0 0 -3 3 .0 - 20.0
- 3 8 .0 0 - 27.0 - 10.0
- 33.0 10.0 - 13.0 20.0
+ + +
22.0 25.0 7.0 20.0
+ 11.0 + 25.0 + 20.0
53
- 22.0 - 2 5 .0 0 - 3 3 .0
- 4 4 .0 - 50.0 - 20.0 - 4 2 .0
- 33.0 - 4 0 .0 0 - 25.0
- 33.0 - 40.0 0 - 25.0
- 22.0 - 15.0 0 - 17.0
- 22.0 + 10.0 + 20.0 0
+ 22.0 + 25.0
Mean ± SE
- 26.0 2.2
- 3 4 .0 2.8
- 24.0 2.9
- 22.0 3.5
-
+ 5.0 4.9
+ 18.0 3.3
Concentrations are in g/ml.
9.0 4.7
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Rat No.
Selective Bi-Agonists and Bronchomotor Function
•/.
189
Table III. Effect of NAB 365 on reversing AC'h-induced bronchoconstriction in the airways of rats (values are the percentage change from control ± SEM) Rat No. ACh It) "
Results
The effect of Fenoterol, Terbutaline and NAB 365 on the resting bronchial tone is shown in figure 1. Neither Fenoterol nor Terbutaline in concentrations ranging from lO-o to 1(H g/ml had an effect on the resting bronchial tone. NAB 365 in concentrations of 10-hg/mi caused an apparent increase in airway luminal diameter in the resting state; at 10-5 and 10-J g/ml, the increase in bronchial luminal diameter was significant (p < 0.05).
10*s
- 2 3 .0
- 3 9 .0
- 19.0
- 17.0 - 4 3 .0 - 25.0
- 15.0 - 2 1 .0 - 20.0
- 31.0
6
- 8.0 - 3 6 .0 - 30.0
8
- 4 0 .0 - 12.0
- 30.0 - 12.0
- 2 0 .0 - 8.0
- 20.0 - 5.0
9
- 14.0 - 17.0
- 10.0 - 17.0
- 6.0 - 10.0
-
33
- 13.0 - 9.0 - 11.0
- 10.0 + 9.0 0
0 + 11.0 + 14.0
+ 5.0 + 18.0 + 20.0
34
-
29.0 30.0 33.0 48.0 35.0
- 26.0 - 2 5 .0 - 29.0 - 30.0 - 2 0 .0
- 2 1 .0 - 25.0 - 2 1 .0 - 20.0 - 8.0
0 + 8.3 + 4.0 - 5.0 + 13.0
39
- 2 6 .0 - 3 0 .0 - 16.0
- 25.0 - 15.0 - 10.0
- 19.0 0 0
- 19.0 0 0
+ 6.0 + 15.0 + 17.0
40
- 29.0 - 38.0
- 23.0 - 20.0
- 14.0 - 15.0
- 7.0 - 15.0
0 - 13.0
43
- 33.0 - 33.0 - 11.0
- 27.0 - 2 2 .0 0
- 2 0 .0 - 2 2 .0 + 11.0
- 9.0 - 11.0 + 22.0
0 - 11.0 + 44.0
44a
- 30.0 - 37.0 - 10.0
- 28.0 - 30.0 0
- 20.0 0 + 43.0
0 0 + 52.0
+ 10.0 + 14.0 + 73.0
Mean ± SE
- 25.0 2.4
- 17.5 2.3
- 10.5 3.4
+ 2.5 6.3
+ 3.0 4.7
6.0 7.0
Concentrations are in g/ml.
Following administration of ACh (K H g/ ml) the airways contracted as a rule by about 25-40% from the control diameter. Terbu taline in concentrations of up to 10-' g/ml
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reversal effect of several concentrations were tested. In preparations that failed to achieve control values after the highest concentration of the drug was applied, cither phentolamine (10_s—10~4 g/ml) or NAB 365 ( 10-5— 10“* g/ml) was then added to the incubating medium and the luminal diameter again measured after 15 min. The following drugs were used: 4-amino-3,5dichlor-a-[(tert-butylamino)-methyl|benzyIalcohol-hydrochloride (NAB 365: Dr. Karl Thomae, Bibcrach); l-(3.5-dihydroxyphcnyl)-2-[( l-[4-hydroxybenzyl]-cthyl)-amino]-ethanol-hydrobromide (Fcnoterol; Boehringer. Ingelheim am Rhein): 2-tcrt-butylamino-l(3,5-dihydroxyphenyl)-ethanol-sulfate (Terbutaline; Astra Chemicals. Wedel/Holstein). and phentolamine hydrochloride (Ciba. Basel).
5 x 10" s 10-i
lO '6 4
ACh + NAB 365
Fig. 4. Reversal effects of NAB 365 on ACh-induced bronchoconstriction in rats. Values are the means.
NAB 365
190
Iravani/Melville
Of the selective B;-mimetics studied, only NAB 365 had an effect on the resting bronchial tone. It could be argued that the airways were not tonically constricted in the resting state to allow for an effect of Feno terol or Terbutaline. This is ruled out by the fact that longitudinal folds, a sign of contrac tion [Iravani et al., 1975], were present in all airways. It has been suggested that airway patency is maintained by a balance between the a- and /3-adrenoceptors and that over activity of the a-receptors or a decreased /?reserve produce clinical exacerbation and bronchoconstriction [MacDonald et at., 1967; Richardson and Sterling, 1969; 57monssonetal., 1969]. Administration of phentolamine alone does not cause bronchodilation but in the presence of a B-adrenergic substance bron chodilation results [Iravani and Melville, 1975 ]. The reason why of all the B,-mimetics only NAB 365 had an effect on both the resting tone and on ACh-induced broncho constriction in the absence of phentolamine is not clear. It is possible that Fenoterol and Terbutaline have in addition to their B2effect, a stimulating effect on the a-receptors which would then nullify or diminish the Discussion expected bronchodilatory effect. The method adopted in this study [/ra B;-Receptors are confined exclusively to vani and Schuler, 1971] allows the study of the smooth muscle of the airways, thus ad bronchomotor function in locally defined ministration of a substance such as acetylcho areas of the tracheobronchial tree. The mus line that affects mainly the contractile ele cle coat as well as the mucociliary apparatus ments in smooth muscle, is a valuable are intact and remain functional for up to method of testing the effectiveness of any 10 h. selective B2-drugs. Although both Fenoterol The factors that modify the bronchomo and Terbutaline have been shown to reduce tor response were pointed out by Iravaniand airway resistance in vivo [Plit et al., 1972; Scinder [1971] and include the avoidance of Benjamin, 1972; Simonsson et al., 1972; blood aspiration or the development of oede Chaieb et al., 1974], in the present study ma and the length of the hypoxic period after neither of the two had an effect on the AChinduced bronchoconstriction unless the asacrificing the animal.
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was ineffective in reversing the ACh-induced bronchoconstriction (fig. 2). After adminis tration of either phentolamine (KM g/ml) or NAB 365 (10 4 g/ml) there was a significant reversal of the ACh-induced response at the 5 and 1% level, respectively (table I). Fenoterol, similarly, was ineffective in reversing the ACh-induced bronchocon striction until the a-receptor sites were blocked by phentolamine, in which case con trol values were achieved at a phentolamine concentration of 10 4 g/ml (fig. 3; table II). In the presence of ACh, Fenoterol and phen tolamine, administration of NAB 365 caused a greater increase in luminal diameter than that obtained with phentolamine (10 4 g/ml). NAB 365 caused a significant reduction of the ACh-induced bronchoconstriction at concentrations above KM g/ml (p < 0.01 ) (table III; fig. 4). In three airways an increased broncho constriction was seen at a NAB 365 concen tration of KM g/ml (table III) and is proba bly due to a mild a-receptor stimulating ef fect in these airways.
Selective Bi-Agonists ami Bronchomotor Function
References Benjamin. C.: The effect of Fenoterol (Berotec) in mine workers with obstructive airway diseases. Med. Proc. IS: 61 (1972). Constantine. H.: Dautrebande. I..; Kaltreider, N.: I.ovejoy, F. W.; Morrow. P.,and Perkins. P.: Influence of carbachol and of fine dust aerosols upon the breathing mechanics and the lung volumes of normal subjects and of patients with chronic respiratory disease before and after administration of sympathicomintetic aerosols. Archs int. Pharmacodyn. Ther. 123:239 (1959). Chaieb. J. A.: Kamburoff. P. L..and Prime, F. J.: Effect of a repeated dose of tcrbutaline by inhalation. Curr. tried. Res. Opinion 2:275 (1974). Gordonoff, T. und Scheinfinkei, N.: Über die Bronchial peristaltik. Klin. Wschr. 16: 167(1937). Hawkins. D. F. and Schild, H. O.: The action of drugs on isolated human bronchial chains. Br. J. Pharmac. Chemother. 6:682 (195 I ). Iravani. J.: Flimmerbewegung in den intrapulmonalen Luftwegen der Ratte. Pflügers Arch. ges. Physiol. 297:221 (1967). Iravani. J. und Melville. G. N.: Wirkung von Bromhexin-Metabolit VIII und einem neuen adrenergen Stoff auf die mukoziliäre Funktion des Respirations traktes. Arzneimittel-Forsch. 2 4:849 (1974). Iravani. J. and Melville. G. N.: Evidence for alpha and beta receptors in the bronchial tree of rats (in prepa ration, 1975). Iravani. J.: Melville. G. N.. and Richter. H. G.: Closing and opening pressures in the intrapulmonary airways of rats. Pneumonologic (submitted for publ.. 1975). Iravani. J. und Schiiler. K. G.: In vitro Untersuchungen der Bronehomotorik der Ratte. Pneumonologie 144 : 253 (1971 ). Kilburn. K. H.: Dimensional responses of bronchi in apneic dogs to airway pressure, gases and drugs. J. appl. Physiol. / 5 ; 229(I960). Konzett. H. und Rössler. R.: Versuchsanordnungen zu Untersuchungen an der Bronchialmuskulatur. Naunyn-Schmiedebergs Arch. exp. Path. Pharmak. 195.1 \ (1940).
Krebs, H. A. und Henseleit, K.: Untersuchungen über die Harnstoffbildung im Tierkörper. Hoppe-Seyler's Z. physiol. Chem. 209:33 ( 1932). Kündig. H.: Preliminary pharmacological and toxicolog ical studies in the baboon (Papio ursinus) on a new Bi-adrencrgicstimulant, Feneterol (Berotec). Med. Proc.S. Afr. /AV9( 1972). MacDonald. A. G.; Ingram. C. G.. and McNeill. R. S.: The effect of propranolol on airway resistance. Br. J. Anaest. 39:919 (1967). Nadel, J. and Clarke. S. WC A new technique for study ing airway deposition, morphology and mechanism using powdered tantalum. Proc. 3rd Int. Symp. on Inhaled Particles, London 1970. pp. 16-23. Plit. M.: Goldman. H. L. and Cassel. M. L.: The bronchodilator action of Feneterol (Berotec) in asthma. Med. Proc. IS: 41 (1972). Radford. E. P. and Lefcoe, N. M.: Effects of bronchoconstriction on elastic properties of excised lungs and trachea. Am. J. Physiol. ISO: 479 (1955). Richardson. P. S. and Sterling, G. M.: Effects of betaadrenergic receptor blockade on airway conduct ance and lung volume in normal and asthmatic sub jects. Br. mcd. J. Hi: 143 (1969). Simonsson. B. G.: Andersson, R.; Bergh, N. P.; Skoogh, B. E.. and Svcdmyr. N.: In vivo and in vitro studies of pharmacological effects on different receptors regu lating bronchial tone in man. Bronchitis III. Proc. of the 3rd Int. Symp. on Bronchitis at Groningen, Netherlands 1969. Simonsson, B. G.; Stiksa, J., and Strom. B.: Double blind trials with increasing doses of salbutamol and tcrbutaline aerosols in patients with reversible air ways obstruction. Acta med. scand. 192:371 (1972). Trendelenburg. P.: Physiologische und pharmakolo gische Untersuchungen an der isolierten Bronchial muskulatur. Arch. exp. Path. Pharmak. 69: 79 (1912). Wiek. H.. Uber die Wirkung der Kohlensäure auf das Trachealpräparat des Hundes. Archs int. Pharmaco dyn. Ther. SS:450(1952).
Received: December 18. 1975 Accepted: February 2. 1976 Dr. G. Norris Melville, Lehrstuhl für Anatomie II. Ruhr-LIniversität Bochum. Universitätsstrasse 150, MA 6/148, D—4630 Bochum (FRG)
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receptors were blocked, thereby confirming earlier findings [Iravani and Schüler, 1971; Ira vani and Melville, 1974).
191
