Effect of Unilateral Pulmonary Artery Obstruction on Circulatory Dynamics in Dogs with Chronic Atrial Septal Defects

Abstract

Simultaneous and continuous recording of venous flow (rotameter) of a femoral and renal bed of the dog revealed dissimilar responses in these regions. Bilateral common carotid occlusion and hypoxia (5 per cent oxygen) cause a greater increase in femoral resistance than in renal resistance. Conversely, levarterenol and angiotensin produce a greater increase in renal than in femoral resistance. Bleeding is associated with resistance changes in opposite directions, the renal bed's resistance increasing, the femoral bed's decreasing. Aortic constriction causes a reduction in the resistance of each bed; the femoral bed's resistance is reduced significantly more than the renal vascular resistance. These results suggest that the femoral bed is more reactive than the renal following baro-receptor- or chemoreceptor-induced changes. In contrast, the renal bed is more susceptible to hormonal stimuli. To those stimuli reducing perfusion pressure, renal blood flow is more likely to be compromised.