ALTERATION IN CA2+ CALMODULIN-SENSITIVE ADENYLYL-CYCLASE ACTIVITY IN THE HIPPOCAMPUS OF STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS/

This study examined the function of adenylyl cyclase (AC) activity in the hippocampus and cerebral cortex of the stroke-prone spontaneously hypertensive rat (SHRSP). Male SHRSP (8-week-old and 25-week-old) were used for the experiments, and age-matched Wistar-Kyoto rats (WKY) wer e used as a genetic control. Basal, forskolin-, and GppNHp-stimulated AC activities were not different between SHRSP and WKY in the 8-week-o ld and 25-week-old groups. Ca2+/calmodulin-sensitive AC activity in hi ppocampal and cerebral cortex membranes was significantly lower in 25- week-old SHRSP than in age-matched WKY, but it was not in the 8-week-o ld group. These results suggest that the function of Ca2+/calmodulin-s ensitive, presumably type I, AC was impaired in the brain of SHRSP. Su ch dysfunction of AC possibly contributes to the behavioral impairment reported in passive avoidance tasks in SHRSP.