Mechanism of anion permeation in the basolateral membrane of isolated rabbit renal proximal tubule S3 segment.
Conventional and double-barreled microelectrodes were used to examine the anion selectivity of Cl- conductance in the basolateral membrane of rabbit renal proximal tubule S3 segment. The permeability sequence determined by anion replacements in the presence of K+ channel blocker quinine was SCN- > I- > Br- > Cl- > gluconate in both nonperfused and luminally perfused tubules. The anion-selective microelectrodes with higher sensitivity to I- enabled us to measure intracellular I- activities. With these electrodes, we could compare the conductive movements of Cl- and I- in response to the increase in bath K+ concentrations and confirmed that the conductance sequence was also I- > Cl-. Although the basolateral potential changes generated by Cl- and Br- currents were stimulated by adenosine 3',5'-cyclic monophosphate (cAMP), the potential changes by SCN- and I- currents were somewhat inhibited by cAMP. In addition, the conductive uptake of I- was, in contrast to that of Cl-, inhibited by cAMP These results are consistent with the existence of at least two distinct anion conductances in this membrane, which are differently regulated by cAMP.
Seki
G
G
First Department of Internal Medicine, Tokyo University School of Medicine, Bunkyo-ku, Japan.
Yamada
H
H
Taniguchi
S
S
Uwatoko
S
S
Suzuki
K
K
Kurokawa
K
K
D000818:Animals; D000838:Anions / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000502:physiology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007454:Iodides / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000502:physiology*; D008564:Membrane Potentials; D011803:Quinine / Q000494:pharmacology; D011817:Rabbits
D000838:Anions; D002712:Chlorides; D007454:Iodides; D005576:Colforsin; D011803:Quinine; D000242:Cyclic AMP