Pulmonary Vascular Responses To Selective Lung Cooling in Intact Dogs

Abstract

Summary

Selective rapid cooling, to 22°, of blood perfusing a hemodynamically separated pulmonary lobe produced abrupt, but transient lobar arterial and venous pressor responses. Abruptly cooling a dextran perfusate produced a sustained pressor response while gradually cooling blood or rapidly cooling saline did not change lobar vascular pressures. In addition, isolated pulmonary arterial strips abruptly relaxed when the bathing medium was suddenly cooled to 22°. These data suggest that increased blood viscosity is largely responsible for the pressor responses to cold blood, but these responses are opposed by the direct vasodilating effect of cold on the vessel wall, and the inhibition of the effects of circulating vasopressor substances by cold.