ALTERATION OF RENAL RECEPTORS FOR ATRIAL-NATRIURETIC-PEPTIDE AND VASOPRESSIN IN SPONTANEOUSLY HYPERTENSIVE RATS TREATED WITH ANTIHYPERTENSIVE DIURETICS

To investigate the alteration of the renal atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) receptors in the controlled hypertensive state of spontaneously hypertensive rat (SHR) treated with antihypertensive diuretics, 12 weeks old SHRs were administered an antihypertensive diuretic, furosemide, trichloromethiazide, or indapamide, daily for 10 days and investigated by radiolabeled receptor assay (RRA) of ANP and AVP. The urine volume was significantly increased in all groups treated with antihypertensive diuretics as compared with the untreated control group on day 3. Systolic blood pressure was significantly decreased in groups treated with both trichloromethiazide and indapamide. The number of renal ANP receptors decreased; affinity was increased only in the SHR administered indapamide. The affinity of the renal AVP receptor was also decreased in that group. Alteration of ANP and AVP receptors was observed only in the group treated with indapamide. This indicates that the ANP and AVP receptor in the kidney of SHR was changed not only by diuresis or reduction of blood pressure, but by the pharmacological action of indapamide.