REARRANGEMENT OF THE VENTRICULAR CAPILLARY NETWORK IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS (SHRSP) FOLLOWING A LATE START OF TREATMENT WITH THE ANGIOTENSIN-CONVERTING ENZYME BLOCKER TEMOCAPRIL

The effects of the angiotensin converting enzyme (ACE) blocker temocap ril on the capillary network of the left ventricle were studied in str oke-prone spontaneously hypertensive rats (SHRSP). The ACE blocker was dissolved in the drinking water and supplied to 24 and 32 week old SH RSP ad libitum for 5 weeks. The capillaries of the wall of the left ve ntricle were studied using a double staining method to differentiate t he arteriolar, intermediate and venular capillary portions. Capillary density increased and capillary domain areas decreased in all capillar y portions compared with untreated control SHRSP in both age groups. T he proportion of venular capillary portions was increased by temocapri l treatment. The results indicate that the late start of ACE blockade caused the regression of the hypertrophied cardiomyocytes, which is ch aracteristic of SHRSP, and the rearrangement of capillary portions. Th e plasma concentration of angiotensin II was significantly lower in te mocapril-treated SHRSP compared to the control group. The implication is that intrinsic angiotensin II exerts an appreciable effect on the f unction, structure and capillary network in the left ventricular wall in SHRSP.