Intrarenal Ghrelin Infusion Stimulates Distal Nephron-Dependent Sodium Reabsorption in Normal Rats

摘要: Ghrelin is a 28-amino acid peptide hormone that exerts powerful orexigenic effects. receptor expression has been reported in the kidney, but role of ghrelin kidney unknown. The present studies confirmed mRNA kidneys normal Sprague Dawley rats (n=6) using reverse transcription polymerase chain reaction (PCR) and sequencing 588-bp PCR product. To test intrarenal action, uninephrectomized received 3 cumulative 1-hour renal interstitial (RI) infusions 5% dextrose water (vehicle, n=21), (n=10), plus specific antagonist [D-Lys-3]-GHRP-6 (n=24), or alone (n=32). Mean arterial pressure (MAP), urine sodium excretion rate (U(Na)V), glomerular filtration (GFR), fractional (FE(Na)), lithium (FE(Li)) were calculated for each period. RI infusion significantly decreased U(Na)V to 86 ± 4.9% (P<0.05), 74 6.5% (P<0.01), 62 10% (P<0.01) baseline during periods 1 3, respectively. also FE(Na) 68 11% 57 8.6% (P<0.001), 59 12% baseline, without changing GFR FE(Li). Identical presence failed permit reductions FE(Na). Following alone, increased from 0.06 0.01 0.18 0.03 μmol/min (P<0.0001). Concomitant increases observed (0.23 0.03% 0.51 0.06% [P<0.001]), changes MAP, GFR, Together, these data introduce novel ghrelin-ghrelin system, which, on activation, Na(+) reabsorption at level distal nephron.