Relaxin-induced changes in renal function and RXFP1 receptor expression in the female rat.

Relaxin causes renal hyperfiltration, natriuresis, and diuresis in male rats. This study determined the effect of recombinant human relaxin (rhRLX) on renal function in the female rat. After 7 days of rhRLX treatment (0.4 microg/h) urinary excretion of sodium and chloride were significantly lower in the rhRLX-treated group, but urine flow rate was not different from that in controls. Quantitative PCR showed that the RXFP1 receptor was expressed in both the renal cortex and medulla; immuno-localization revealed expression in the proximal tubule and inner medullary collecting ducts. These data show that relaxin elicits pregnancy-like changes in renal function in the female rat.