Pattern of differential vasoconstriction in response to acute and chronic low-output states in the conscious dog.

The extent to which the mesenteric, renal, and iliac beds respond with vasoconstriction to the low-output state of chronic failure was studied in conscious dogs with experimental heart failure produced by tricuspid insufficiency and pulmonary stenosis. While intense vasoconstriction occurred in the mesenteric and iliac beds, the renal circulation was relatively spared. A similar pattern of response was observed in a second group of normal conscious dogs when cardiac output and arterial pressure were acutely decreased by partial occlusion of the inferior vena cava.