Permeability of rat diaphragm muscle to some methyl glycosides and its relationship to monosaccharide transport.

1. Studies in vitro have shown that rat diaphragm muscle is freely permeable to alpha- and beta-methyl d-xylosides and beta-methyl l-arabinoside but not to alpha- or beta-methyl d-glucoside or alpha-methyl d-mannoside. 2. No competition for entry between methyl pentosides and d-xylose, l-arabinose, d-glucose or 3-O-methyl-d-glucose could be demonstrated and alpha-methyl xyloside entry was not inhibited by phlorrhizin. 3. It is concluded that the monosaccharide transport system is unlikely to contribute significantly to the entry of the methyl pentosides in this tissue.