Biochemical and ultrastructural correlates of substrate stimulation of renal organic anion transport.

Penicillin pretreatment enhanced the rate of PAH uptake into separated proximal tubules (collagenase digestion) from 2-week New Zealand white rabbits. A double reciprocal plot of these data suggests that penicillin increases the maximal velocity of PAH uptake. Na, K-ATPase was less in adult tissue but was unaffected by penicillin. No ultrastructural changes could be attributed to the treatment. Thus substrate stimulation of PAH transport does not involve Na, K-ATPase and probably involves soluble, rather than structural proteins.