Histamine-evoked potassium release in the mouse and guinea pig pancreas

An investigation was made of the effects of histamine on the K+ concentration in the effluent in superfused guinea pig and mouse pancreatic segments. The effect of acetylcholine (ACh) was examined for comparison. Histamine evoked a dose-dependent and transient increase in the K+ concentration in the effluent (K+ release) but is less potent compared to the cholinergic agonist, ACh. At the same doses histamine and ACh evoke a much larger K+ release from mouse superfused pancreatic segments followed in the poststimulus period by a reuptake of K+. However, this reuptake of K+ was not observed in guinea pig superfused pancreatic segments. On the other hand, the cholinergic antagonist, atropine, completely abolished the K+ release in response to ACh and histamine from mouse and guinea pig pancreatic segments. Our results show the involvement of histamine in the control of K+ release in pancreatic tissue, with significant differences in the observed responses between species.