Effect of mucosal potassium on the intestinal glucose transport

Summary The extracellular space (inulin or raffinose space) and the intracellular concentration of sodium and potassium were determined in the intestinal mucosal scrapings of rats following a perfusion of the intestine with isosmotic solutions of electrolytes or non-electrolytes. Following a perfusion with K₂SO₄ or mannitol, the intracellular concentration of potassium increased significantly. Perfusion with sorbitol or raffinose did not produce such change. Mannitol (but not sorbitol or raffinose) increased the rate of mediated diffusion (but not that of active transport) of glucose from the gut lumen. It is concluded that the increased glucose absorption is due to the high intracellular concentration of potassium which causes an enhanced metabolic disappearance of the free intracellular glucose. In light of modern concepts regarding the intestinal absorption of glucose and of the findings of present and related studies, Verzár's theory concerning the role of intracellular metabolism (phosphorylation) in the absorption is reassessed.Dedicated to Prof. F. Verzár on the occasion of his 80th birthday.Supported by grants from the U. S. Public Health Service and from the American Heart Association.