Distribution of parathyroid hormone-sensitive adenylate cyclase in isolated rabbit renal cortex microvessels and glomeruli

Abstract

The effect of the synthetic amino-terminal fragment of bovine parathyroid hormone, bPTH-(1–34), on the adenylate cyclase of microvessels and glomeruli isolated from rabbit kidney cortex was studied in the presence and absence of guanosine triphosphate (GTP). bPTH-(1–34) stimulated the vascular and glomerular adenylate cyclase in a dose-dependent manner with apparent ED 50 values of 11.5 nM and 64 nM respectively, in the absence of GTP. 10 −4M GTP greatly amplified the vascular response to bPTH-(1–34) while, in the glomeruli, both GTP, and bPTH-(1–34) had only additive effects. In the presence of GTP, vascular and glomerular apparent ED 50 were 190 nM and 64 nM respectively. [Nle 8, Nle 18, Tyr 34] -bPTH-(3–34) amide, described as a PTH antagonist, inhibited the action of bPTH-(1–34) in the microvessels and to a lesser extent in the glomeruli. PTH is therefore a potent stimulator of adenylate cyclase in rabbit renal microvessels and glomeruli, and may play a role in the regulation of renal blood flow and glomerulo-tubular feedback control.