Does tissue ATP content limit active sodium transport across intestinal epithelia in vitro?

The ATP content of isolated epithelia of rabbit descending colon, incubated in oxygenated Ringer solution containing glucose, is increased by addition of 1 mM adenosine from 10.9 +/- 1.4 to 22.2 +/- 2.3 pmoles/mg, but the transport rate of the Na pump is not altered. It is therefore concluded that epithelial ATP synthesis is not rate-limiting for Na transport in this tissue under conditions of in vitro aerobic incubation.