Renal hemodynamic response to intrarenal infusion of calcitonin gene-related peptide in dogs.

The renal hemodynamic and excretory effects of intrarenal infusions of synthetic beta-human calcitonin gene-related peptide (beta-hCGRP) were examined in normal sodium replete dogs (Group 1, n = 6), in sodium replete dogs pretreated with indomethacin (Group 2, n = 6), and in sodium deplete dogs (Group 3, n = 5). In all groups of anesthetized dogs beta-hCGRP was infused at 5 and 10 ng.kg-1.min-1 for 50 min periods each. In the sodium replete group, beta-hCGRP infusions strikingly increased renal blood flow, but this response was markedly attenuated in the other 2 groups. During beta-hCGRP infusions, the clearance of creatinine also increased significantly in the sodium replete and deplete groups, but not in the indomethacin pretreated animals. No consistent changes in urinary sodium excretion or plasma renin activity were observed with beta-hCGRP infusions in any of the 3 groups of dogs. These results indicate that beta-hCGRP is a potent renal vasodilator and can increase renal blood flow and glomerular filtration. The data also suggest that the renal hemodynamic actions of beta-hCGRP are partially mediated by renal prostaglandins, and that the vasodilatory effects of beta-hCGRP may be antagonized by high circulating levels of endogenous angiotensin II in sodium-volume depletion. Finally, beta-hCGRP does not appear to have significant actions on urinary sodium excretion or plasma renin activity under the experimental conditions of the present study.