Nle3, D‐Phe6]‐gamma melanocyte stimulating hormone (NDP γMSH), increases glomerular filtration rate (GFR) in high salt fed rats

Abstract

This study examined the cardiovascular and renal actions of the natriuretic peptide γMSH with those of a synthetic analogue, NDP‐γMSH.Both γMSH and NDP‐γMSH were infused systemically (3–1000 nmol/kg) and intrarenally (500 fmol/min) into innervated and renally denervated normal and high salt fed rats. The effect of the infusion of these peptides on mean arterial pressure (MAP), urinary sodium excretion, urinary output, GFR and fractional sodium excretion was measured.Both renal and systemic infusion of γMSH increased MAP by 23±2% and 54±4% respectively but no pressor effects were observed upon renal or systemic infusion of NDP‐γMSH. The analogue increased urine flow and sodium excretion by 2–3 fold in fed a normal salt (0.4% Na+) diet and by 6–7 fold in rats fed a high salt (4% Na+) diet and induced a 3.5‐fold increase in GFR in high salt fed rats compared to normal salt fed controls. These renal effects of NDP‐γMSH were not abolished by prior renal denervation.NDP‐γMSH possessed the natriuretic but not the cardiovascular properties of γMSH. These natriuretic effects occur independently of renal innervation suggesting a direct effect of NDP‐γMSH on the kidney.