Dogs were subjected to four consecutive bleedings of 5 ml/kg with an interval of 10 min between each. Blood flow in the renal, superior mesenteric, and common iliac arteries was measured with the electromagnetic flowmeter. Control blood flows averaged 448, 199, and 134 ml/min for superior mesenteric, renal, and iliac arteries, respectively. After 20 ml/kg blood was removed, superior mesenteric flow declined by 45%, renal by 52%, and common iliac by 40%. Calculated renal resistance increased little until after removal of 10 mg/kg blood, but there was a sharp increase after removal of 20 ml/kg. Mesenteric and iliac resistances increased from the onset of hemorrhage.

No abstract

By following changes in arterial-coronary sinus plasma potassium concentration differences, the myocardial potassium balance was studied during the increased heart rate produced by cardioaccelerator nerve or right atrial stimulation. With cardioaccelerator nerve stimulation there was an initial loss of myocardial potassium of brief duration, followed by an uptake for the duration of the stimulation. Atrial stimulation leads predominantly to a loss of myocardial potassium, particularly when the reflex effects of marked cardiac acceleration were minimized by cardioaccelerator nerve excision and support of venous return by abdominal binding. It is suggested that the chronotropic action of cardiac sympathetic nerves tends to cause a loss of potassium, but that this is normally circumvented by some other action of the nerves in promoting potassium uptake.

No abstract

This paper is concerned with the pattern of eardiorespiratory and renal changes produced by opening a. systemic arteriovenous fistula. Flow through bilateral femoral arterinvenous fistulas averaged approximately 53 per cent of the control cardiac output. The rise in cardiac output elicited by the shunt averaged oL per cent of the shunt flow. PAH clearances decreased 23 per cent in animals anesthetized with sodium pentobarbit:if, and 46 per cent in animals premedieated with morphine sulfate prior to administration of sodium pentobarbital. The per rent reduction in renal blood flow did not differ significantly from the per cent reduction in flow through the extvarenal systemic capillary beds.T,nT{oelie, Inc.