215
Plasma Atrial Natriurefic Peptide in Elite Runners E. Toft, E. Ernst, G. T Espersen, and S. Kdlund Departments of Clinical Chemistry and Clinical Immunology, Aalborg Hospital, Aalborg, Denmark
E. Toft, E. Ernst, G. T Espersen, and S. Kdlund, Plasma Atrial Natriuretic Peptide in Elite Runners. IntJSportsMed, Vol 1l,No3,pp215—217, 1990. Accepted after revision: September 19, 1989
Plasma atrial natriuretic peptide (ANP) was measured in relation to a 5-km race in 11 elite mid- and long-
distance runners. Plasma ANP, measured in relation to the
race, was compared with the relative changes in plasma volume and the physical fitness of the runners. Relative changes in plasma volume were estimated by changes in hemoglobin and hematocrit, and physical fitness was evaluated by a cycle ergometer test, running time, and resting heart-rate.
In connection with the race, plasma ANP increased in all the runners. Median plasma ANP was 4.7 before the race and 12.9 pmolV' immediately pmoll
after the race. No correlation was found between the
changes in ANP and the relative changes in plasma volume or the measurements of physical fitness. A volume expansion of the red blood cells was found immediately after the race.
We conclude that well-conditioned subjects have a prominent rise in plasma AMP, in spite of a high maximal cardiac output.
both peripheral and central modulating effects on cardiovascular and renal function. ANP is secreted in response to atrial distension
(1). It is suggested that circulating hormones (cathecholamines and vasopressin-arginine) may also stimulate the secretion of ANP (12). Increased plasma levels of ANP were reported in patients with cardiac (15) and renal diseases, as well as in normal subjects during pregnancy (7). Moreover, plasma ANP has been shown to rise in response to exercise for untrained as well as moderately trained subjects (3, 4, 6, 8, 11, 13, 14). The increments in plasma AMP were proportional to the work intensity (14). In a single previous study (3) of wellconditioned subjects, no measurements and grading of physical fitness were performed. The physiological significance of ANP in normal subjects is unclear. In order to elucidate this problem, measures of plasma volume and urine excretion in relation to ANP levels would be of interest. A significant correlation between ANP levels and changes in hemoglobin during exercise has been found (8). In the present study ANP levels and changes in plasma volume were measured in well-conditioned runners in connection with a 5-km race. The aim of the study was to describe the plasma levels of ANP in well-conditioned subjects in
Key words
connection with a maximal effort and to relate changes in ANP with the estimated changes in plasma volume and the
Atrial Natriuretic Peptide, plasma volume,
physical fitness.
exertion, physical fitness.
Materials and Methods Subjects: The study included 11 male mid- and
Introduction Atrial natriuretic peptide (ANP) is a hormone which is mainly produced in the myocytes of the cardiac atria.
In addition, the anterior pituitary gland, the kidney, and several other tissues contain small amounts of ANP and the hormone is furthermore secreted in the brain (7). ANP in-
mt. J. Sports Med. 11(1990)21 5—2 17
Georg Thieme Verlag StuttgartNew York
long-distance runners. All subjects were physically fit with normal blood pressure. Weekly training distance ranged from 80km to 160 km (mean 118 km) and the subjects were from 23 to 42 years old. Physical fitness (condition) was evaluated by a cycle ergometer test (16), and was further estimated from the times used for the 5-km run and from morning resting heart-
rate. The study was approved by the local ethical committee and the subjects gave their informed consent. Experimental protocol: In relation to the run, blood samples were drawn I week before (sample 1), immediately after the race (sample 2), 2 hours (sample 3), and 24 hours (sample 4) after the race.
Downloaded by: University of Connecticut. Copyrighted material.
Abstract
creases glomerular filtration, natriuresis, and diuresis and reduces peripheral vascular resistance via an antagonistic action on angiotensin II in the endothelium of the blood vessels (7, 10). ANP has also been shown to have an effect on the regulation of blood pressure (7). The hormone seems, thus, to have
E. Toft, E. Ernst, G. T Espersen, and S. Kdlund
216 mt. J. Sports Med. 11(1990) Laboratory measurements: For ANP measurements, samples were chilled with ice and immediately centrifuged for 30 minutes at 4 C. ANP was measured in samples Nos. 1, 2, and 3. Blood was drawn into tubes prepared with
dipotassium-ethylenediaminetetraacetic acid (EDTA) and aprotinin. Subjects were placed in supine position for I mm before the venipuncture. ANP was extracted on SEP-PAK Cit cartridges which had been prepared with methanol and acetic acid, and the quantity was determined by a radioimmunoassay
kit (Amersham, -Human-ANP Radioimmunoassay). Inter-
Plasma ANP
pmolxr1 60
50
assay coefficient of variation was 6.3 %. In 35 normal subjects
plasma ANP levels were 5.3±1.7 pmor' (mean±1 SD). Hemoglobin, hematocrit, and mean cell volume (MCV) were measured on a Technicon H-I (Technicon Instruments, Terrytown, New York, USA). The relative change in plasma volume was estimated using the following equation (2, 6). (Hbpr (100— Hctpo) 100%
-
30
100%
(Hb0 (100—Hctpr) (Pr =prior to exercise, po immediately = after exercise).
20
Statistics: Correlation analysis was done using the Spearman Rho test. Wilcoxons signed ranked sum test was
used for statistical comparison of ANP and hemoglobin values before and after the race. Statistical significance was chosen for p < 0.05 (two-tailed). For description of data, mean values 1 SD were presented.
10
Results 1
2
The performance measured on the cycle ergometer was 71.6± 17.3 mlO2kg 1min
3
and the runSample
ning times averaged 16 mm 42 sec± 1 mm 11 sec. The resting
heart rate was 46.8±5.2 min.
In Fig. I plasma ANP results are shown. Plasma ANP concentration increased from 5.5 pmoll to 21.7 4.8 pmol 1 immediately after the 5-km race and returned to the prerace values (4.8 pmoll 1 1.2 pmoIV 1) 2 hours after the race. The plasma ANP increased by a factor of 4.0±2.6 from sample 1 to sample 2 (range 1.9 to 9.5, median 3.1) (Wilcoxons signed rank sum test, p 0.1, Mann-Whitney test). Plasma ANP in-
creased to 32.5 pmoll', 40 pmoll', and 65 pmoll' in
Fig. 1 Plasma ANP in 11 elite runners in connection with a 5-km run. Plasma ANP levels increased from sample 1 (before the run) to sample 2 (immediately after the run) and decreased to a pre-run level in sample 3 (2 hours after the run). In some of the subjects very high values of plasma ANP were reached in sample 2.
ANP (0.2 > p> 0.1, r= 0.53). No correlation between changes in plasma ANP levels and cycle ergometer test, running time, morning resting heart rate, and weekly training distance was found (Spearman Rho test, p > 0.2). changes in
three runners. Discussion
Hemoglobin increased in connection with the race (Wilcoxons signed rank sum test, p
Plasma Atrial Natriurefic Peptide in Elite Runners E. Toft, E. Ernst, G. T Espersen, and S. Kdlund Departments of Clinical Chemistry and Clinical Immunology, Aalborg Hospital, Aalborg, Denmark
E. Toft, E. Ernst, G. T Espersen, and S. Kdlund, Plasma Atrial Natriuretic Peptide in Elite Runners. IntJSportsMed, Vol 1l,No3,pp215—217, 1990. Accepted after revision: September 19, 1989
Plasma atrial natriuretic peptide (ANP) was measured in relation to a 5-km race in 11 elite mid- and long-
distance runners. Plasma ANP, measured in relation to the
race, was compared with the relative changes in plasma volume and the physical fitness of the runners. Relative changes in plasma volume were estimated by changes in hemoglobin and hematocrit, and physical fitness was evaluated by a cycle ergometer test, running time, and resting heart-rate.
In connection with the race, plasma ANP increased in all the runners. Median plasma ANP was 4.7 before the race and 12.9 pmolV' immediately pmoll
after the race. No correlation was found between the
changes in ANP and the relative changes in plasma volume or the measurements of physical fitness. A volume expansion of the red blood cells was found immediately after the race.
We conclude that well-conditioned subjects have a prominent rise in plasma AMP, in spite of a high maximal cardiac output.
both peripheral and central modulating effects on cardiovascular and renal function. ANP is secreted in response to atrial distension
(1). It is suggested that circulating hormones (cathecholamines and vasopressin-arginine) may also stimulate the secretion of ANP (12). Increased plasma levels of ANP were reported in patients with cardiac (15) and renal diseases, as well as in normal subjects during pregnancy (7). Moreover, plasma ANP has been shown to rise in response to exercise for untrained as well as moderately trained subjects (3, 4, 6, 8, 11, 13, 14). The increments in plasma AMP were proportional to the work intensity (14). In a single previous study (3) of wellconditioned subjects, no measurements and grading of physical fitness were performed. The physiological significance of ANP in normal subjects is unclear. In order to elucidate this problem, measures of plasma volume and urine excretion in relation to ANP levels would be of interest. A significant correlation between ANP levels and changes in hemoglobin during exercise has been found (8). In the present study ANP levels and changes in plasma volume were measured in well-conditioned runners in connection with a 5-km race. The aim of the study was to describe the plasma levels of ANP in well-conditioned subjects in
Key words
connection with a maximal effort and to relate changes in ANP with the estimated changes in plasma volume and the
Atrial Natriuretic Peptide, plasma volume,
physical fitness.
exertion, physical fitness.
Materials and Methods Subjects: The study included 11 male mid- and
Introduction Atrial natriuretic peptide (ANP) is a hormone which is mainly produced in the myocytes of the cardiac atria.
In addition, the anterior pituitary gland, the kidney, and several other tissues contain small amounts of ANP and the hormone is furthermore secreted in the brain (7). ANP in-
mt. J. Sports Med. 11(1990)21 5—2 17
Georg Thieme Verlag StuttgartNew York
long-distance runners. All subjects were physically fit with normal blood pressure. Weekly training distance ranged from 80km to 160 km (mean 118 km) and the subjects were from 23 to 42 years old. Physical fitness (condition) was evaluated by a cycle ergometer test (16), and was further estimated from the times used for the 5-km run and from morning resting heart-
rate. The study was approved by the local ethical committee and the subjects gave their informed consent. Experimental protocol: In relation to the run, blood samples were drawn I week before (sample 1), immediately after the race (sample 2), 2 hours (sample 3), and 24 hours (sample 4) after the race.
Downloaded by: University of Connecticut. Copyrighted material.
Abstract
creases glomerular filtration, natriuresis, and diuresis and reduces peripheral vascular resistance via an antagonistic action on angiotensin II in the endothelium of the blood vessels (7, 10). ANP has also been shown to have an effect on the regulation of blood pressure (7). The hormone seems, thus, to have
E. Toft, E. Ernst, G. T Espersen, and S. Kdlund
216 mt. J. Sports Med. 11(1990) Laboratory measurements: For ANP measurements, samples were chilled with ice and immediately centrifuged for 30 minutes at 4 C. ANP was measured in samples Nos. 1, 2, and 3. Blood was drawn into tubes prepared with
dipotassium-ethylenediaminetetraacetic acid (EDTA) and aprotinin. Subjects were placed in supine position for I mm before the venipuncture. ANP was extracted on SEP-PAK Cit cartridges which had been prepared with methanol and acetic acid, and the quantity was determined by a radioimmunoassay
kit (Amersham, -Human-ANP Radioimmunoassay). Inter-
Plasma ANP
pmolxr1 60
50
assay coefficient of variation was 6.3 %. In 35 normal subjects
plasma ANP levels were 5.3±1.7 pmor' (mean±1 SD). Hemoglobin, hematocrit, and mean cell volume (MCV) were measured on a Technicon H-I (Technicon Instruments, Terrytown, New York, USA). The relative change in plasma volume was estimated using the following equation (2, 6). (Hbpr (100— Hctpo) 100%
-
30
100%
(Hb0 (100—Hctpr) (Pr =prior to exercise, po immediately = after exercise).
20
Statistics: Correlation analysis was done using the Spearman Rho test. Wilcoxons signed ranked sum test was
used for statistical comparison of ANP and hemoglobin values before and after the race. Statistical significance was chosen for p < 0.05 (two-tailed). For description of data, mean values 1 SD were presented.
10
Results 1
2
The performance measured on the cycle ergometer was 71.6± 17.3 mlO2kg 1min
3
and the runSample
ning times averaged 16 mm 42 sec± 1 mm 11 sec. The resting
heart rate was 46.8±5.2 min.
In Fig. I plasma ANP results are shown. Plasma ANP concentration increased from 5.5 pmoll to 21.7 4.8 pmol 1 immediately after the 5-km race and returned to the prerace values (4.8 pmoll 1 1.2 pmoIV 1) 2 hours after the race. The plasma ANP increased by a factor of 4.0±2.6 from sample 1 to sample 2 (range 1.9 to 9.5, median 3.1) (Wilcoxons signed rank sum test, p 0.1, Mann-Whitney test). Plasma ANP in-
creased to 32.5 pmoll', 40 pmoll', and 65 pmoll' in
Fig. 1 Plasma ANP in 11 elite runners in connection with a 5-km run. Plasma ANP levels increased from sample 1 (before the run) to sample 2 (immediately after the run) and decreased to a pre-run level in sample 3 (2 hours after the run). In some of the subjects very high values of plasma ANP were reached in sample 2.
ANP (0.2 > p> 0.1, r= 0.53). No correlation between changes in plasma ANP levels and cycle ergometer test, running time, morning resting heart rate, and weekly training distance was found (Spearman Rho test, p > 0.2). changes in
three runners. Discussion
Hemoglobin increased in connection with the race (Wilcoxons signed rank sum test, p
