Possible involvement of protein kinase C in the maintenance of hypertension in spontaneously hypertensive rats

Calcium-activated phospholipid-dependent protein kinase (protein kinase C) and cyclic AMP-dependent protein kinase (protein kinase A) were measured in tissue extracts of aortas from 7-, 14− and 20-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Protein kinase C and protein kinase A activity was significantly higher in 14− and 20-week-old SHR. Furthermore, protein kinase C and protein kinase A activity in the aorta was positively correlated with systolic blood pressure. Since protein kinase A is known to relax vascular smooth muscle, the observed increase in its activity may represent a compensatory mechanism to offset further elevation of blood pressure in SHR. These results suggest that protein kinase C in the aorta may play a role in the maintenance of hypertension in SHR.