Some effects of ouabain and potassium on transport and metabolism in rat small intestine.

1. Ouabain (10(-3)M) inhibited the transfer of glucose, proline, methionine and fluid but not of galactose and 3-O-methyl glucose by sacs of rat everted intestine.2. Ouabain (10(-3)M) inhibited both glucose and mannose metabolism. Hexose metabolism was also reduced by varying the [K] from 4.8 m-equiv/l.3. Ouabain (10(-3)M) or absence of K reduced the stimulation of amino acid, hexose and fluid transfer by mannose. Although presence of ouabain or absence of K did not inhibit endogenous galactose transfer, these conditions prevented mannose from stimulating this transfer.4. Ouabain (10(-3)M) exerted greater effects on hexose and amino acid transfer when K was omitted from the saline and its inhibitory effects were partially overcome by increased serosal [K].5. Ouabain (10(-2)M) caused further inhibition of amino acid and glucose transfer and also reduced the transfer of galactose and 3-O-methyl glucose.6. The implications of these results are discussed with respect to the relationships between cations and hexose and amino acid transfer.