Lack of altered cyclic nucleotide phosphodiesterase activity in the aorta and heart of the spontaneously hypertensive rat.

DEAE-cellulose chromatography demonstrated that the levels of the individual cyclic nucleotide phosphodiesterases were unchanged in the aorta and heart of the spontaneously hypertensive rat as compared with the normotensive control rat. Three peaks of cyclic nucleotide phosphodiesterases activity were observed in both heart and aorta. Peak I enzyme hybrolyzed predominantly cyclic GMP while peak III enzyme hydrolyzed predominantly cyclic AMP. Peak II enzyme was less specific but hydrolyzed more cyclic GMP than cyclic AMP. The levels of phosphodiesterase activator in aorta and the responsiveness of peaks I and II from aorta and heart to activator were unchanged in the hypertensive rat. Therefore the decrease in cyclic AMP levels observed by others in aorta and heart of the spontaneously hypertensive rat were probably not due to altered phosphodiesterase activity.