alpha-Adrenoreceptor stimulation of the systemic circulation in dogs

The influence of phenylephrine (an alpha-adrenoreceptor agonist) on the arterial and venous systems of the systemic circulation was studied in 10 anesthetized dogs during a right ventricular bypass procedure. Phenylephrine (1 microgram X kg-1 of body weight X min-1) produced a significant (P less than 0.001) increase in arterial resistance, no change in venous resistance, and a mild decrease in venous compliance. Seemingly in the clinically normal dog, a dose of phenylephrine sufficient to double total peripheral resistance will redistribute a small amount of blood volume from the venous to arterial systems with a slight decrease in venous return and concomitant attenuation of cardiac output.