Fragmentation of the Actin Filaments by Acute Pressure Overload to the Right Ventricle of the Conscious Dog.

Abstract

We have postulated in a study of the isolated cat papillary muscle that the disparity between muscle length and sarcomere length may be the result of myofibrillar fragmentation. In contrast, Saphir and Karsner demonstrated in the rabbit myocardium subjected to an acute pressure overload, that segmentation or separation of intercalated discs occurred, and not myofibrillar fragmentation.In order to determine whether the myocardial fragmentation produced in the in vitro study has pathophysiological significance in the intact myocardium, tissues were studied from the right ventricle of the conscious dog subjected to an acute pressure overload.In order to produce the overload, we utilized a specially designed triple lumen pulmonary artery balloon distension catheter. This catheter can measure simultaneous pulmonary arterial and right ventricular pressures. The catheter was inserted through the jugular vein and wedged under flouroscopic control in a branch of the pulmonary artery. The balloon was situated in the main pulmonary artery.