Cyclic nucleotide phosphodiesterase in the aorta of spontaneously hypertensive rats : variation with age and effect of propranolol.
The activities of cyclic AMP- and cyclic GMP-phosphodiesterase were studied in the aorta (freed of the adventitia layer) of spontaneously hypertensive rats (SHRs). At the time of weaning (3 weeks of age) young SHRs were separated into two groups. One group was chronically treated with propranolol, 50 mg.kg-1 daily for 4 weeks (treated rats), with treatement beginning either at the time of weaning or at 15 weeks of age. The second group (non-treated SHRs) was used as control. In both groups we observed that the protein content per aorta but not the DNA content increased parallel to the organ weight. The enzyme activities were related to the DNA content of aorta. In non-treated SHRs, the phosphodiesterase activties increased with age, but there was a considerable lag of time between the marked increase in blood pressure that occured between 5 and 12 weeks of age and the increase in phosphodiesterase activity which started after 12 weeks of age. Prolonged propranolol treatment significantly decreased both blood pressure and enzyme activities when started at the time of weaning but had no effect when given to mature SHRs. Thus, the effects of propranolol on blood pressure and on phosphodiesterase activities were associated, whereas no correlation could be established between the age-dependent increases in blood pressure and in phosphodiesterase activities in aorta cells of the SHR.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000032:analysis*; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000032:analysis*; D000367:Age Factors; D000818:Animals; D001011:Aorta / Q000201:enzymology*; D004247:DNA / Q000032:analysis; D006973:Hypertension / Q000188:drug therapy / Q000201:enzymology*; D008297:Male; D011433:Propranolol / Q000494:pharmacology*; D011506:Proteins / Q000032:analysis; D051381:Rats
D011506:Proteins; D004247:DNA; D011433:Propranolol; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases