STREPTOZOTOCIN-INDUCED DIABETES-MELLITUS IN SPONTANEOUSLY HYPERTENSIVE RATS - A PATHOPHYSIOLOGICAL MODEL FOR THE COMBINED EFFECTS OF HYPERTENSION AND DIABETES

The present study was undertaken to investigate the combined effects o f hypertension and streptozotocin-induced diabetes mellitus in the rat . Accordingly, four groups of rats were studied: Wistar Kyoto rats (WK Y), diabetic WKY, spontaneously hypertensive rats (SHR) and diabetic S HR, respectively. The mean arterial blood pressure was increased in hy pertensive animals compared to normotensive animals. The base excess i n the diabetic rats was higher than that of normogly cemic animals. An elevated glucose concentration was found in the blood and urine of st reptozotocin-treated rats. Ketone bodies were detected in the urine an d blood of the diabetic rats. Mortality rates after treatment were not different among the four groups. In separate experiments, isolated wo rking hearts of the various groups were set up and analyzed. For the m aximal left ventricular pressure (mm Hg) the following values were for med: 110.0 +/- 2.6, 93.6 +/- 2.7, 93.4 +/- 3.0, and 87.5 +/- 2.4, resp ectively. The wet heart weights, dry heart weights, and body weights o f the diabetic rats were lower than those of normoglycemic animals. Th e wet heart weight/body weight ratio, however, was increased by diabet es and hypertension (0.43 +/- 0.01, 0.47 +/- 0.01, 0.47 +/- 0.01, and 0.54 +/- 0.02, respectively). There were no significant differences be tween the water content of the hearts from the four different groups. Pathologic examination of the hearts showed myocardial hypertrophy and medial hypertrophy of coronary arteries in diabetic and hypertensive animals. There was no difference in relative collagen content in the h earts of the four groups. In conclusion, the experimental procedure us ed appears to be an unique model to study the effects of diabetes and hypertension separated as well as combined.