EXPERIMENTAL PULMONARY HYPERTENSION

Abstract
Pulmonary arterial hypertension was induced in the dog by 3 different procedures: ligation of 1 or more pulmonary veins; left atrial hypertension by aortic-atrial shunt; and experimental silicosis accompanied by peri-arterial adventitious stenosing sclerosis and early thrombosed capillary lesions. It has been established that the passive or paralytic distension (by silicosis) of the venous side of the vascular tree determined at an early stage a diminution in the calibre of the venules with hypertrophy of the musculo-elastic tissue of the wall. The reaction of the venous side preceded the same reaction at the level of the pulmonary arterial segment. This reaction of the parietal vascular tissues of the whole pulmonary tree is attributed to the distension. The reflexes at intervals resulting from the excitation of presso-receptive endings of the veins and of the juxtavenous portion of the left atrium are probably also playing a part.