The Journal of pharmacology and experimental therapeutics
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J. Pharmacol. Exp. Ther. · Jun 1985
Comparative StudyAlpha-1 adrenergic control of the venous circulation in intact dogs.
To study alpha adrenergic control of the venous circulation, 17 dogs were lightly sedated and instrumented with thermodilution pulmonary flow and aortic catheters. Hemodynamics, cardiac output and central blood volume were measured at rest. Mean circulatory filling pressure, pressure gradient for venous return and resistance to venous return were calculated from pressures obtained during transient acetylcholine-induced circulatory arrest. ⋯ To eliminate reflex changes in vascular tone, eight dogs received ganglionic blockade with trimethaphan. After ganglionic blockade phenylephrine increased cardiac output, systemic vascular resistance, mean circulatory filling pressure, pressure gradient for venous return and central blood volume (P less than .025). Thus, in conscious dogs, phenylephrine reduces peripheral vascular capacitance and shifts blood from the venous circulation to the central and arterial vascular compartments.