[Comparative study of the role of cAMP, cGMP and Ca2+ in the action of the antidiuretic hormone on bladder cells of the frog].

Vasopressin (ADH), forskolin and cAMP raise osmotic pressure of the frog bladder; cGMP does not change the response of cells to cAMP and forskolin action but it increases the ADH effect. Being added from the mucous or serous membranes, Ca channel blocker (fendiline) and calmodulin antagonist (thioridazine) inhibit the water effect of ADH. The results obtained indicate a number of loci where Ca2+ is in ADH-dependent reactions which cause an increase in osmotic permeability.