Abstract
The distribution of atrial natriuretic polypeptide (ANP) and atrial specific granules in the myocytes of the atria and ventricles of an experimental animal model, stroke-prone spontaneously hypertensive rats (SHRSP) and a control, Wistar Kyoto rats (WKY), was examined using immunocytochemical and electron microscopic techniques. In the atria of both SHRSP and WKY, ANP-immunoreactivity was recognized in the perinuclear regions of essentially all cardiac myocytes. In the ventricles of WKY, ANP-immunoreactivity was hardly seen except for the impulse-conducting system. However, in the ventricles of SHRSP, almost all cardiac myocytes possessed immunoreaction products which were scattered evenly throughout the cytoplasm; this distribution pattern differed from that of the atrial wall of this strain.
