Evidence for adenylyl cyclase-dependent receptors for parathyroid hormone (PTH)-related protein in rabbit kidney glomeruli.

Studies were conducted to test whether parathyroid hormone-related protein (PTHrP) is able to stimulate adenylate cyclase activity in isolated rabbit glomeruli. Maximal stimulations were reached at 10(-7) M of human PTHrP-(1-34) or rat PTH-(1-34) and showed a 3-3.3 fold increase over basal activity. The potency (EC50) values were close to 10(-9) M. The guanyl nucleotide GTP, at 10(-5) M, potentiated the effect of PTH and PTHrP but reduced their potency. The combined effect of maximal concentrations of PTHrP and PTH was not additive, and the PTH antagonist [Nle8.18, Tyr34]-bPTH-(3-34)amide inhibited both PTHrP- and PTH-stimulated adenylate cyclase activities. These findings suggest that PTHrP could affect glomerular function through changes in glomerular cAMP content by interaction with PTH receptors.