TREATMENT IN HYPERTENSIVE CARDIAC-HYPERTROPHY .1. NEUROPEPTIDE-Y AND BETA-ADRENOCEPTORS

In the present study, we investigated serum and myocardial neuropeptide Y concentrations as measures of sympathetic activity as well as myocardial beta-adrenoceptors and beta-adrenoceptor-stimulated adenylyl cyclase activity in spontaneously hypertensive rats (SHR). SHR and control rats at 10 weeks of age were kept on oral treatment with captopril, nitrendipine, or both for 20 weeks. Treatment only slightly reduced but did not normalize blood pressure and cardiac hypertrophy in SHR. The elevated serum concentration of neuropeptide Y, the reduced number of beta-adrenoceptors, and the depressed beta-adrenoceptor-stimulated adenylyl cyclase activity were partly normalized compared with the values observed in control rats. We conclude that antihypertensive treatment, at doses that failed to normalize systolic pressure and to reverse cardiac hypertrophy completely, is able to reduce sympathetic activity in SHR, thereby resensitizing the depressed beta-adrenoceptor-adenylyl cyclase system.