Parathyroid hormone stimulation of renal adenylate cyclase in various vertebrate species: evidence for an effect in the frog.

The effect of [Nle8,18,Tyr34]bPTH-(1-34)amide on renal plasma membrane adenylate cyclase, in the presence of 0.1 mM guanylylimidodiphosphate was measured in rat, chicken, frog and trout. All species showed an enrichment of at least 8-fold (relative to homogenate) in the marker enzyme Na+,K+-ATPase. A significant dose-dependent adenylate cyclase stimulation was found in frog, with affinity values similar to those of rat and chicken (ED50=8, 10 and 3 nM, respectively), but not in trout. The frog response was specific since [Nle8,18,Tyr34]bPTH-(3-34)amide strongly inhibited the agonist-stimulated enzyme. These results suggest the existence of a PTH-like substance in anurans acting via cyclic AMP formation in the kidney.