Effect of Sympathetic Nerve Stimulation on Pulmonary Vascular Resistance in the Intact Spontaneously Breathing Dog

Abstract

SummaryThe effects of sympathetic nerve stimulation on pulmonary vascular resistance under conditions of controlled blood flow were evaluated in the intact spontaneously breathing dog. Stimulation of the sympathetic nerves to the lung resulted in a significant stimulus-related increase in pulmonary vascular resistance in the intact animal. Injected norepinephrine had similar effects on the pulmonary vascular bed and responses to both norepinephrine and nerve stimulation were blocked by phentolamine, an alpha receptor blocking agent. It is concluded that the pressor response to nerve stimulation is mediated by alpha receptors in the pulmonary vascular bed and that this response is similar in magnitude in both the intact spontaneously breathing and open-chest animal.