In vivo heterologous regulation of rat glomerular and vascular atrial natriuretic factor receptors by angiotensin II

Abstract

Since glomerular and vascular atrial natriuretic factor (ANF) receptor density may vary inversely with circulating ANF concentration, and the latter may respond to changes in blood pressure, we investigated whether ANF receptors are modified by a pressor agent, angiotensin II. Rats were infused intraperitoneally for 6 days with either a non-pressor (200 ng/kg per min) or pressor dose (800 ng/kg per min) of angiotensin II. Blood pressure was higher and plasma renin activity lower in the pressor than in the non-pressor or sham-infused groups. Plasma ANF was elevated only in animals infused with a pressor dose of angiotensin II. Glomerular ANF receptor density was higher in the non-pressor (Bmax = 1308 +/- 360 fmol/mg protein) and lower in the pressor (Bmax = 459 +/- 13 fmol/mg protein) than in the sham-infused group (Bmax = 755 +/- 303 fmol/mg protein). In vitro, angiotensin II-precontracted isolated glomeruli from animals infused with a pressor dose of angiotensin II were less sensitive to the relaxant effect of low ANF concentrations (10(-12) and 10(-11) mol/l) than those receiving a non-pressor dose of angiotensin II or sham-infused. Vascular ANF receptor density was similar in the control and non-pressor groups (Bmax = 64 +/- 12 and 62 +/- 20 fmol/mg protein, respectively) and decreased in the pressor group (Bmax = 30 +/- 4 fmol/mg protein). Norepinephrine-precontracted aorta strips from rats receiving a non-pressor dose of angiotensin II were more sensitive to the relaxant effect of ANF.(ABSTRACT TRUNCATED AT 250 WORDS)