The effect of various intraluminal substrates on the magnitude of the transepithelial potential difference (PD) across the proximal convoluted tubule (PCT) of the mammalian kidney was investigated in two ways. First, the transepithelial PD was measured before and after the removal of glucose, bicarbonate, and alanine from the lumen. Second, the effects of specific transport inhibitors—ouabain, phloridzin, and acetazolamide—was ascertained when placed either on luminal or blood side.
