Acta pharmacol. et toxicol. 1978,43, 111-1 18

From the Department of Clinical Pharmacology, Institute of Pharmacology, University of Aarhus, Aarhus, Denmark, the Gynaecological Department, Norwegian Radium Hospital, Oslo, Norway, and the Department of Obstetrics and Gynaecology ,University Hospital, Malmo, Sweden

Effects of Nifedipine on the Smooth Muscle of the Human Urinary Tract in Vitro and in Vivo BY

A. Forman, K.-E. Andersson, L. Henriksson, T. Rud and U. Ulmsten (Received December 13, 1977;Accepted January 30,1978)

Abstract: Smooth muscle preparations of the urethra, bladder, and ureter were obtained from patients undergoing operations for various urological disorders. The urethral preparations were contracted by noradrenaline (0.1-3p g ml-'),prostaglandin F2. (1-10 pg ml-I), and potassium (127 mM), the bladder preparations by carbacholine (0.004-1p g ml-I), prostaglandin F,, (1-10 p g * ml-'), potassium (127mM), and barium chloride (3 mM), and the ureter preparations by potassium (127 mM), and barium chloride (3 mM). Irrespective of the mode of activation, pretreatment with nifedipine (0.1 pg * ml-') for 10 min. reduced the responses. Nifedipine also relaxed preparations contracted by the contractile agents used. In 19 female patients, aged 20 to 73 years, undergoing investigation because of urgency andor urge incontinence, simultaneous urethrocystometry at rest was performed before and after oral administration of 20 to 40 mg nifedipine. Bladder capacity and residual urine were also determined. Nifedipine did not affect the pressures within the bladder and urethra, nor did it increase the bladder capacity. However, after nifedipine intake there was a statistically significant increase in residual urine. The results suggest that nifedipine can inhibit contractile activity induced by drugs with different modes of action; the drug does not affect the tone in bladder and urethra.

-

-

-

Key-words: Nifedipine - calcium antagonism - man - lower urinary tract - smooth muscle - isometric tension - simultaneous urethrocystometry - bladder capacity - residual urine.

Recent studies on the adrenergic and choliner- son et al. 1977) not directly related to the autongic innervation (Schulman 1975; Ek et a1 omous nervous system may be involved in the 1977a; Sundin et a1 1977), and on the distribu- regulation of smooth muscle function in this tion and function of adreno- and cholinoceptors region. in urinary tract smooth muscle (see, Nergslrdh Like in other types of muscle, the contractile 1975, Ek et al. 1977 b) have opened new ways activity of the smooth muscle of the urethra, for the pharmacological treatment of functional bladder, and ureter is ultimately controlled by disorders of the lower urinary tract in man. the concentration of intracellular free calcium. They have also demonstrated that structures Inhibition of the inflow of calcium in the (Larsson et al. 1977 a,b), and agents (Abrams smooth muscle cell can be selectively obtained & Feneley 1976; Bultitude et al. 1976, Anders- by calcium antagonists (for a recent review, see

112

A. FORMAN ET AL.

Fleckenstein 1977). Nifedipine is one of the most potent calcih antagonists available (Fleckenstein et al. 1975, Fleckenstein 1977), and has been widely used clinically in the treatment of ischaemic heart disease (Ebner & Diinschede 1976). A recent study also suggested its value in the treatment of uterine hyperactivity as found in dysmenorrhoea (Andersson & Ulmsten 1978). In the present study, the action of nifedipine on the isolated smooth muscle of the human urinary tract was investigated. In addition, its effects on the pressures within the bladder and urethra at rest were studied in patients.

Mat&aIs and Methods I n Vitro: Tissue specimens of detrusor and ureter were obtained from 9 patients (3 men and 6 women, aged 10 to 70 years) undergoing operations on the bladder and the distal third of the ureter for various urological disorders.All pieces of tissue were macroscopically normal. None of these patients had received radiation therapy before the operation. Urethral tissue was obtained from 2 men and 3 women undergoing total cystourethrectomy after preoperative radiological treatment because of malignancy of the bladder. From each patient, tissue specimens were obtained from different parts of the urethra. All preparations were immediately placed in chilled Krebs solution and transported to the laboratory, where they were mounted within 1-2 hrs. The pieces of bladder tissue were dissected as transmural strips (n = 20), and the ureter specimens as ring preparations (n = 29). The urethral specimens were dissected as tubal segments. These were cut open and mounted as strips of tissue (n = 12). allowing investigation mainly of the circular muscle layer. Reparations were mounted in jacketed, thermostatically controlled organ baths (30 ml) containing Krebs solution (379 bubbled with 95% O2 and 5% C02. Isometric tension was recorded by means of a Grass Ft 03 transducer co~ecteedto a Beckman R 611 polygraph. Initial tension was set at approximately 0.5 g for all preparations. After a period of equilibration of about 1 hr. contractile responses were elicited. These were repeated at 30-min. intervals until reproducible. Solutions: The normal Krebs solution used had the NaCl ): 119, KCl 4.6, following composition (a NaHC03 20, CaC12 1.5, MgCl 1.2, NaH2P04 1.2, glucose 11; pH 7.40. Potassium-rich Krebs solution: KC1 127, NaHC03 20, CaCl2 1.5, MgCl2 1.2, NaH2P0, 1.2. glucose 11; pH 7.40. All solutions were prepared on the day of the experiment. The chemicals used were of analytical grade. Drugs: Carbacholine (DAK, Denmark), norad

renaline bitartrate (DAK,Denmark), prostaglandin F, (Upjohn, USA), prostaglandin El, prostaglandin E, (AB ASTRA, Sweden), barium chloride (Merck AG, West Germany). Nifedipine (Bayer AG, West Germany) was supplied in ampoules containing 0.1 mg ml-l. The ampoules were kept dark at 4' and opened just before use. All concentrations given are final bath concentrations. I n Vivo: Patients. Nineteen patients, aged 20 to 73 years (mean 51 years) were investigated. They were sent to the Urogenital laboratory of the Department of Gynaecology, University Hospital of Malmo, with a diagnosis of urgency andor urge incontinence. None of them was found to have uninhitited detrusor contractions. They were all informed of the aim of the investigation and the experimental procedures involved, and gave their consent. Pressure recording: The patients were investigated by simultaneous urethrocystometry including measurement of the urethral pressure profile using the technique described by Asmussen & Ulmsten (1976 a,b). The intra-urethral pressure, the intravesical pressure, and the difference between these, i.e., the urethral closure pressure were recorded simultaneously by means of a catheter with two microtransducers. After amplification, the pressure signals were registered by an ink-jet recorder (Mingograf 81, Siemens Elema, Sweden). Experimental procedure: The patient was asked to micturate before the investigation. She was then placed in the semilithotomy position. After controlling residual urine, the pressure recording catheter was introdud together with a thin (0.d. 1.32 mm) infusion catheter. The bladder was filled with 100 ml body warm saline and three measurements of the urethral pressure profile were made. From these, the resting bladder pressure, the maximum intraurethral pressure, and the urethral closure pressure were calculated. The bladder was then filled with body warm saline at a rate of 100 ml- min.-* until a sensation of strong urge was reported or the patient voided spontaneously. The infused volume was taken as a measure of bladder capacity. After this, the bladder was emptied completely by micturition or by catheterization. The patients were given 20 to 40 mg nifedipine as a single oral dose. The drug was supplied (by Bayer AG, West Germany) in capsules containing 10 mg. One or two of the capsules were chewed before swallowing. After 20 min. the bladder was again filled with 100 ml body warm saline, and the initial expenmental procedure was repeated. Blood pressure and pulse rate (auscultation) were recorded before and at 20-min. intervals after administration of nifedipine until the investigation was completed. Specimens for urine cultures were taken before, immediately after, and 14 days after the investigation.

-

NIFEDIPINE AND HUMAN URINARY TRACT

113 L

4

. I

W

5OmN]

5

mN

I

2min

,-I

10 min

'

4

c*

Nif

Fig. 2. Contraction induced by potassium (K+),127 mM, in the isolated human bladder (upper tracing), and the relaxing effects of nifedipine (Nif), 0.1 Fg mi-' (lower tracing). W = wash.

-

7

I

4

NA Fig. 1. Contraction induced by noradrenaline (NA), 1.0 p g * ml-' in the isolated human male urethra before (upper tracing), and after pretreatment with nifedipine, 0.1 p g * d-', for 10 min. (lower tracing).

4

f

-

lOmN]

W

10 min

Results In Vitro Urethra: The urethral preparations were contracted by noradrenaline (0.1-3pg * ml-'), prostaglandin F,, (1-10pg ml-l) and potas-

-

sium. Irrespective of the mode of activation of the muscle, nifedipine (0.01-0.1 pg * ml-') relaxed contracted preparations, and, when added to the bath 10 min. before the contractile agents, inhibited the responses (fig. 1). Bladder: Potassium-rich Krebs solution elicited a diphasic contractile response with an initial tension peak followed by a plateau with maintained tension. When added during the plateau phase, nifedipine (0.1 pg ml-l) relaxed the preparation almost completely (fig. 2). Pretreatment with nifedipine (0.1pg = ml-') for 10. min. inhibited both phases effectively; the plateau was reduced almost to the basic tension level (fig. 3). Carbacholine (0.004-0.1 p g ml-l) produced a transient contraction of bladder strips. This response was strongly diminished by pretreatment with nifedipine (0.1 pg * ml-l) for 10 minutes (fig. 4). When added on top of a con-

.

G

c

4

K'

W

Fig. 3. Contraction induced by potassium (K'), 127 mM, in the isolated human bladder before (upper tracing), and after pretreatment with nifedipine, 0.1 Fg * ml-', for 10 min. (lower tracing). W = wash.

4

4

Carb

W

h 4

4

Carb

W

Fig. 4. Contraction induced by carbacholine (Carb), 0.1 p g mi-', in the isolated human bladder before (upper tracing), and after pretreatment with nifedipine 0.1 Fg d - l , for 10 min. (lower tracing). W = wash. +

-

A. FORMAN ET AL.

114

c

4+

IOmN]

c

4

PGF2,, Nif

Fig. 5 . Contraction induced by prostaglandin F,, (PGF,,), 10 pg * ml-', in the isolated human bladder (upper tracing), and the relaxing effects of nifedipine (Nif), 0.1 pg ml-' (lower tracing). W = wash.

-

50mN]

-

-

K

W

10 min

4

k+

W

Fig. 7. Contraction induced by potassium (K+),127 mM, in the isolated human ureter before (upper tracing), and after pretreatment with nifedipine, 0.1 pg ml-', for 10 min. (lower tracing). W = wash.

-

4

W

10 min

4

4+ K

W

4+ K

Nif

4

Ba

Fig. 6. Contraction induced by barium chloride (Ba), 3 mM, in the isolated human bladder, before (upper tracing) and after pretreatment with nifedipine, 0.1 pg * ml-', for 10 min. (lower tracing). W = wash.

traction, nifedipine caused a rapid relexation to the basic tension level. Prostaglandin F2, (1-10 pg * ml-'1 caused a relatively slowly developing contraction with superimposed rapid oscillations in tension. Pretreatment for 10 min. with nifedipine reduced the response. When given on the top of the contraction, nifedipine 0.1 pg ml-' relaxed the preparation completely (fig. 5 ) . Barium chloride (3mM) induced a persistent tonic contraction of the bladder muscle. After 10 min. pretreatment with nifedipine (0.1 pg * ml-I), the response to barium was diminished and transient; the strips relaxed almost to the basic tension level (fig. 6).

.

4

Fig. 8. Contraction induced by potassium (K+),127 mM, in the isolated human ureter (upper tracing), and the relaxing effect of nifedipine (Nif), 0.1 p g ml-' (lower tracing). W = wash.

-

Ureter: In the ureter preparations, potassium produced a diphasic response, similar to that in the bladder. During the development of the initial phase, rapid, transient contractions were often observed (fig. 7). Pretreatment with nifedipine for 10 min. abolished these tension shifts, and inhibited the following response effectively (fig. 7). When given on the plateau of the potassium contracture, nifedipine, 0.1 pg ml-', caused an almost complete relaxation (fig. 8 ) .

-

NIFEDPINE AND HUMAN URINARY TRACT

20mN]

noradrenaline produced a small increase in tension. In all preparations, the effect of nifedipine persisted for several hours after washing.

4 4 4 +

4

Ba

-

115

w w w w

10 min

In Vivo In the 19 patients receiving 20 to 40 mg nifedipine, only small and statistically nonsignificant changes were found in the urethral 4 4 Ba Nif and bladder pressures. The mean maximun Fig. 9. Contraction induced by barium chloride (Ba), urethral pressure was 68.1 cm H,O (range 1333 mM,in the isolated human ureter (upper tracing), 35 cm H,O) before nifedipine, and 65.5 cm and relaxing effect of nifedipine (Nif), 0.1 p,g mi-' H,O (range 105-29 cm H,O) after. The bladder (lower tracing). W = wash. pressure changed from a mean of 17.5 cm H 2 0 (range 27-10 cm H20) to 18.8 cm H,O (range Barium chloride (3mM) induced a small rise 38-10 cm H,O), and urethral closure pressure in tone with superimposed fast tension shifts. from 50.6 cm H,O (range 109-19 cm H,O) to Both components of the response were 46.5 cm H 2 0 (range 83-15 cm H,O). Bladder capacity did not change (358 ml beabolished by nifedipine when given on the top of the contraction (fig. 9), or when the prepara- fore, 365 d after). However, there was a statistically significant increase in residual urine tion was pretreated with the drug for 10 min. Prostaglandin Fza, 1-10 pg * ml-',prostag- from 12 to 67 ml (p

Effects of nifedipine on the smooth muscle of the human urinary tract in vitro and in vivo.

Acta pharmacol. et toxicol. 1978,43, 111-1 18 From the Department of Clinical Pharmacology, Institute of Pharmacology, University of Aarhus, Aarhus,...
574KB Sizes 0 Downloads 0 Views