AJP - Heart and Circulatory Physiology, Vol 242, Issue 6 1065-H1076, Copyright © 1982 by American Physiological Society
Reflexes elicited by acute stretch of atrial vs. pulmonary receptors in conscious dogs
H. D. Schultz, D. C. Fater, W. D. Sundet, P. G. Geer and K. L. Goetz
We measured hemodynamics and renal function in conscious dogs while
partially obstructing blood flow at various sites within the thorax.
Inflation of a balloon in the left atrium increased left atrial pressure
(LAP) by 9 mmHg and caused a parallel increase in pulmonary arterial
pressure (PAP); heart rate, arterial pressure, and total peripheral
resistance increased; stroke volume and right atrial pressure decreased;
and cardiac output remained unchanged. The increase in LAP was accompanied
by a fourfold increase in urine flow and a threefold increase in sodium
excretion. Plasma vasopressin (AVP) and renin activity (PRA) decreased. On
the other hand, partial occlusion of the pulmonary veins or the main
pulmonary artery produced similar increases in PAP without affecting LAP,
systemic hemodynamics, renal function, or plasma AVP. Similarly, inflation
of a balloon in the right atrium failed to alter renal function, plasma
AVP, or PRA. Finally, constriction of the thoracic inferior vena cava
decreased LAP and increased PRA. In summary, these data emphasize that
inflation of a balloon in the left atrium of the conscious dog produces a
composite response consisting of alterations in cardiovascular function,
renal function, and circulating hormones. Moreover, our data indicate that
the response is mediated by a reflex initiated from receptors located in
the left atrium; we detected no evidence that receptors located in the
pulmonary vasculature or right heart contribute to this response.
