MITOCHONDRIAL DAMAGE IN THE MYOCARDIUM OF SPONTANEOUSLY HYPERTENSIVE RATS

In spontaneously hypertensive mts (SHR), varying degrees of structural damage were seen in the mitochondria of atrial myocytes. The lesions ranged from focal areas of clearing of the mitochondrial matrix in app roximately 20% of mitochondria, to extensive clearing with focal disru ption and disorientation of mitochondrial membranes in approximately 7 %. In ventricular myocytes of SHR the vast majority of mitochondria ap peared structurally normal, although focal clearance of the matrix was seen in approximately 3%. Atrial and ventricular mitochondria in the myocytes of normotensive control Wistar-Kyoto mts (WKR) appeared intac t or showed a low percentage (about 1%) of organelles with focal matri cal clearance. The respiratory control indices (RCI) of atrial and ven tricular mitochondria of SHR were significantly lower than those of mi tochondria of WKR. The more severe degree of structural damage in atri al mitochondria of SHR was reflected in a significantly lower RCI of a trial than of ventricular mitochondria in of SHR. We conclude that str uctural and functional impairment, especially of atrial mitochondria, is a significant feature of the cardiac pathology of SHR.