The Pulmonary Veins

Abstract

The pulmonary veins are a distensible reservoir between the pulmonary capillaries and the left atrium. Their walls contain muscle and elastic tissue and a rich supply of nerve cells. These vessels dilate and can hold relatively large quantities of blood at low pressures inresponse to rapid transfusion, acute elevation of left atrial pressure, and specific pharmacologic and physiologic stimuli. Acute distention of their walls produces reflex constriction of the pulmonary arteries. Pulmonary venoconstriction is most easily demonstrated under experimental conditions in which this response is not obscured by changes in pulmonary blood flow and volume from the concurrent systemic effects of the same stimulus. Pulmonary venous constriction occur s in the perfused isolated lung after various physiologic and pharmacologic stimuli, and was demonstrated in the intact dog after such stimuli as hypoxia, immersion in cold water, and mild hemorrhagic shock.