Effect of norepinephrine on renal tubular Na-K-ATPase and oxygen consumption.

Previous studies from this laboratory have demonstrated that norepinephrine (NE) increases sodium dependent phenylalanine uptake by in vitro rat cortical tubules. In the present study, we have examined whether the observed increase in proximal tubular sodium transport, during NE treatment, is related to changes in membrane Na-K-ATPase and cellular oxygen consumption. Treatment of intact tubules with NE increased microsomal Na-K-ATPase activity but had no effect on cellular oxygen consumption or ouabain inhibitable oxygen consumption. The increased Na-K-ATPase activity is consistent with the observed increase in sodium transport while the lack of a detectable effect on oxygen consumption suggests that the increased transport does not require additional oxygen utilization.