Calcitonin gene-related peptide stimulates carbonic anhydrase activity in trout gill membranes.

The effect of human calcitonin gene-related peptide (hCGRP) on carbonic anhydrase activity in trout branchial membranes was investigated. hCGRP stimulated the carbonic anhydrase activity, 5-fold over the basal value. This effect was specific: in the presence of sCT only a 2.4-fold increase was observed. Rat amylin that has a 43% homology with hCGRP had no effect on carbonic anhydrase activity. On the other hand hCGRP(8-37), which is a partial antagonist, inhibited the hCGRP-stimulated carbonic anhydrase activity. This effect was observed at low hormonal concentration and suggests the involvement of hCGRP in regulating carbonic anhydrase activity in this important target organ for CO2 exchange.