Species difference in the secretory response to dopamine in the pancreas of dogs, cats, rabbits and rats.

The effects of dopamine and L-dopa on the exocrine secretion of the pancreas were compared in rats, cats, rabbits and dogs. Dopamine and its precursor, L-dopa, induced a secretin-like stimulation in dogs, while their effects were significantly less in rats. The dopaminergic receptor stimulus was involved in the exocrine secretion of the pancreas in dogs, whereas in rats, the beta-adrenergic receptor was involved. Spontaneous secretion in the resting state was present in rabbits but absent in cats. This spontaneous secretion in rabbits could be definitely inhibited by either dopamine or L-dopa. The secretin-induced secretion in both rabbits and cats was markedly inhibited by either dopamine or L-dopa. Species difference in the secretory response to dopamine in the pancreas of dogs, cats, rabbits and rats may be ascribed to the difference in the incorporation of exogenous L-dopa and dopamine in the exocrine cells of the pancreas.