Previous work showed that with 2 x 10-5 M para aminohippurate (PAH) in bath of control Ringer (3 mM K+), net PAH transport occurred from bath to lumen against concentration gradient primarily in distal part of isolated perfused snake proximal renal tubules. Cell water [PAH] was greater than that in bath or lumen, suggesting active uptake into cells and passive diffusion into lumen. In present studies, removal of K+ from bath led within 40 min to depression of net PAH transport from bath to lumen, but transport still occurred against concentration gradient. Cell water [PAH] was markedly depressed, but was still greater than in bath or lumen. Since decreased cell water [PAH] and net PAH transport could have resulted from increased peritubular membrane permeability, this was determined from PAH efflux from tubules with oil filled lumens. These data suggest that removal of K+ depresses active uptake of PAH into cells. When K+ was restored to bath after 40 min perfusion without K+, net PAH transport doubled within 20 min. Cs+ could not replace K+ as requirement for PAH transport. Increasing K+ in bath to 40 mM depressed net PAH transport by about 50% in 20 min.
|Original language||English (US)|
|Number of pages||1|
|Issue number||3 I|
|State||Published - Jan 1 1974|
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