Participation of histamine and cyclic nucleotides in the regulation of gastric secretion in experimental thyrotoxicosis

Experiments on 48 Wistar rats evidence that in early times of hyperthyroidism, the action of thyroxine on parietal cells is mediated by histamine and cAMP, while in prolonged hyperthyroidism, its action on parietal cells refractory to endogenous histamine and cAMP is found to be unmediated and direct.