AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 5 1098-R1102, Copyright © 1989 by American Physiological Society
Plasma atriopeptin during exercise in dogs under beta-blockade
F. Peronnet, S. A. Adjoa, L. Beliveau, D. Bichet, R. Nadeau and G. Brisson
Departement d'Education Physique, Universite de Montreal, Quebec, Canada.
The purpose of this study was to describe plasma atriopeptin concentrations
at rest and in response to moderate treadmill exercise (10 min, 4 km/h, 26%
slope) performed with or without nonspecific beta-adrenergic blockade (1
mg/kg iv propranolol) in 10 mongrel dogs [19 +/- 2 (SE) kg]. A small (20%)
but significant (P less than 0.05) increase in plasma atriopeptin
concentration was observed from rest (43 +/- 5 pg/ml) to exercise (52 +/- 6
pg/ml) without beta-blockade. Propranolol significantly reduced heart rate
at rest (89 +/- 7 vs. 104 +/- 7 beats/min) and during exercise (96 +/- 10
vs. 176 +/- 11 beats/min), and this was associated with a larger increase
in plasma atriopeptin concentration during exercise (rest 46 +/- 6 pg/ml;
exercise 171 +/- 22 pg/ml). Exercise under beta-blockade is associated with
an increased preload of the heart. These results further support the
hypothesis that atriopeptin release during exercise is under the control of
atrial stretch. The higher plasma atriopeptin concentration observed during
exercise under beta-blockade may contribute to the reduction of the
response of plasma renin activity (1.0 +/- 0.1 vs. 3.0 +/- 0.6 ng.ml-1.h-1)
and aldosterone concentration (87 +/- 36 vs. 138 +/- 25 pg/ml). Vasopressin
concentration was lower at rest and during exercise under propranolol (3.5
+/- 1.3 vs. 4.9 +/- 0.9 and 6.1 +/- 2.2 vs. 9.9 +/- 1.5 pg/ml,
respectively), which might reflect a dissociation between activity of the
renin-angiotensin system and vasopressin release.
