Altered distribution and properties of cAMP-dependent protein kinase isozymes in spontaneously hypertensive rat aorta.

cAMP-dependent protein kinase activity was reduced in the cytosol fraction of spontaneously hypertensive rat (SHR) aorta compared to that of the Kyoto Wistar control rat (WKY). Two major peaks, isozymes I and II, of soluble cyclic AMP-dependent protein kinase activity could be separated by DEAE-cellulose chromatography. The distributions of isozymes I and II were 40 and 60%, respectively, in WKY compared to 26 and 74% in SHR. Isozyme I of SHR eluted at a conductance of 2-3 mmhos compared to 5-6 mmhos in WKY. In addition, activity under the peak of isozyme I of SHR was reduced by approximately 55% compared to WKY. The half-life of thermal denaturation of isozyme I at 50 degrees was 21 min in WKY compared to 84 min in SHR. On the other hand, for isozyme II no significant differences were observed between WKY and SHR in elution pattern, total activity under the peak, or thermal denaturation of enzyme activity. These data suggest that specific changes had occurred in isozyme I of SHR.