Antagonistic changes of blood flow and sympathetic activity in different vascular beds following central thermal stimulation

Summary Blood flow in arteries mainly supplying cutaneous, muscular or intestinal vascular regions and aortic blood flow were measured with an electromagnetic flowmeter in anesthetized dogs immobilized with succinyl choline. Up to 3 flows were recorded simultaneously with mean arterial pressure during thermal stimulation of the spinal cord at constant, neutral ambient air temperatures.In conformity with earlier observations, skin blood flow increased during moderate and strong spinal cord heating and was reduced during spinal cord cooling. Conversely, intestinal blood flow decreased during heating in all experiments and increased during cooling in 5 out of 10 experimental animals.Aortic blood flow and muscle blood flow did not change substantially during either heating or cooling. Arterial pressure showed a moderate rise during strong heating, but was not influenced by cooling and moderate heating.The changes of blood flow distribution observed in the experiments are in keeping with results obtained under external thermal stimulation. It is assumed that the antagonistic changes of blood flow in the cutaneous and intestinal vascular beds were induced by antagonistic changes of sympathetic vasoconstrictor activity.A portion of this work was presented at the 37. Congress of the Deutsche Physiologische Gesellschaft, 10.–11. April 1970 [Pflügers Arch.316, R 25, (1970)].