Effect of indapamide on atrial natriuretic polypeptide receptor in spontaneously hypertensive rat kidney.

The effect of a hypotensive state on atrial natriuretic polypeptide (ANP) receptors of the kidney treated by indapamide was investigated in spontaneously hypertensive rats (SHRs). SHRs aged 12 weeks were injected intraperitoneally with indapamide (10mg/kg/day) for 10 days and an ANP radiolabeled receptor assay (RRA) was done on the 11th day. The systolic blood pressure of SHRs injected with indapamide (IDP group) was statistically lower than that of SHRs injected with 2% gum Arabic solution (control group). Concerning the RRA of ANP in the SHR kidney, high affinity and low capacity binding sites were observed in the IDP group (Kd = 0.220 +/- 0.059 nM, Bmax = 6.10 +/- 2.36 fmol/100 micrograms) compared with the control group (Kd = 0.401 +/- 0.147 nM, Bmax = 9.96 +/- 2.50 fmol/100 micrograms). These finding suggested that the hypotensive state induced by treatment with indapamide may change the ANP receptor in kidneys of a SHR.