[Monosaccharide-dependent potassium ion influx across the microvilli membrane of the rat jejunum].

1. The condidtions were studied under which the Na+-dependently transported monosaccharides influence the K+-influx across the microvilli membrane of rat jejunum. 2. The Na+-dependent, energy requiring transport of monosaccharides causes a decrease of the K+-influx, whereas monosaccharides metabolizable by the intestinal mucosal cells - under suitable conditions - induce an increase in the K+-influx. 3. These results indicate that the K+-influx may be controlled by an energy dependent system in the microvilli membrane, which is influenced by metabolism and monosaccharide transport. It is discussed that this control system may be a (Na+ + K+)-ATPase.