AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 2 259-R267, Copyright © 1988 by American Physiological Society
Natriuresis during atrial distension and a concurrent decline in plasma atriopeptin
K. L. Goetz, B. C. Wang, P. Bie, R. J. Leadley Jr and P. G. Geer
Division of Experimental Medicine, St. Luke's Hospital and Foundation, Kansas City, Missouri 64111.
In the conscious dog, left atrial distension elicits a composite response
that modulates both cardiovascular and renal function. The response to
atrial distension may be mediated by the combined effects of neural
reflexes and the release of atriopeptin. To assess the relative
contributions of atrial reflex mechanisms and circulating atriopeptin to
the renal response elicited by atrial distension, alpha-human atrial
natriuretic peptide (alpha-hANP) was infused into conscious dogs at 50
ng.kg-1.min-1 for 60 min. Then the infusion was stopped abruptly, and left
atrial pressure was increased 8 mmHg by inflating a balloon positioned
above the mitral valve. Plasma atriopeptin decreased during the 40-min
period of atrial distension, but urine flow and sodium excretion increased
during this time. In another series of experiments, volume expansion was
substituted for atrial distension. Saline (24 ml/kg) was infused
intravenously for 5 min immediately after the 60-min period of alpha-hANP
infusion. Urine flow and sodium excretion increased after administration of
saline even though plasma atriopeptin decreased substantially during the
same time period. These results provide evidence that circulating levels of
atriopeptin do not play a dominant role in influencing sodium excretion
either during atrial distension or in response to saline infusion.
