Effects of Vasopressors on the Microcirculation and on Survival in Hemorrhagic Shock

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Abstract
In order to re-evaluate the vasoexcitor-pressor principle of drug therapy in shock, the amine, norepinephrine, and 2 polypeptides angiotensin and phenylolanyl-2-lysyl-8-vasopressin (PLV-2,) were compared in their microcirculatory effects and for their influence on survival rates in rats after hemorrhagic shock, Norepinephrine resulted in increased vascular sensitivity to epinephrine, and unselective intense constriction of all microcirculatory components leading to capillary ischemia, depression of vasomotion and venular stasis. Angiotensin produced decreased sensitivity to epinephrine and less intense arteriolar constriction, allowing better capillary inflow. Vasomotion was depressed and venular atony and stasis were prominent. PLV-2 also decreased epinephrine sensitivity and allowed better capillary inflow. Vasomotion and venular tone were sustained and little stasis was observed. Survival rates were favorably influenced only by PLV-2. The data suggest that the vasoexcitor prinicple of therapy, not apparently achieved with the amine pressor, may be realized with more appropriate vasoexcitor drugs.