AJP - Endocrinology and Metabolism, Vol 258, Issue 5 E775-E779, Copyright © 1990 by American Physiological Society
Interactive effect of body posture on exercise-induced atrial natriuretic peptide release
C. A. Ray, M. D. Delp and D. K. Hartle
Department of Physical Education, University of Georgia, Athens 30602.
The purpose of this investigation was to test the hypothesis that supine
exercise elicits a greater atrial natriuretic peptide (ANP) response than
upright exercise because of higher atrial filling pressure attained in the
supine posture. Plasma ANP concentration ([ANP]) was measured during
continuous graded supine and upright exercise in eight healthy men at rest
after 4 min of cycling exercise at 31, 51, and 79% of posture-specific peak
oxygen uptake (VO2 peak), after 2 min of cycling at posture-specific VO2
peak, and 5 and 15 min postexercise. [ANP] was significantly increased (P
less than 0.05) above rest by 64, 140, and 228% during supine cycling at 51
and 79% and VO2 peak, respectively. During upright cycling, [ANP] was
significantly increased (P less than 0.05) at 79% (60%) and VO2 peak
(125%). After 15 min of postexercise rest, [ANP] remained elevated (P less
than 0.05) only in the supine subjects. [ANP] was 63, 79, and 75% higher (P
less than 0.05) in the supine than in the upright position during cycling
at 51 and 79% and VO2 peak. Systolic, diastolic, and mean blood pressures
were not significantly (P greater than 0.05) different between positions in
all measurement periods. Heart rates were lower (P less than 0.05) in the
supine position compared with the upright position. In conclusion, these
results suggest that supine exercise elicits greater ANP release
independent of blood pressure and heart rate but presumably caused by
greater venous return, central blood volume, and concomitant atrial filling
pressure and stretch.
