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Electrophysiological study of the antiluminal membrane in the proximal tubule of Necturus : effect of inorganic anions and SCN −
Author(s) -
Anagnostopoulos Takis
Publication year - 1977
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1977.sp011803
Subject(s) - necturus , depolarization , chemistry , paracellular transport , membrane potential , conductance , transepithelial potential difference , biophysics , tubule , electrophysiology , hyperpolarization (physics) , tetramethylammonium , analytical chemistry (journal) , membrane , iodide , ion , inorganic chemistry , permeability (electromagnetism) , kidney , stereochemistry , endocrinology , medicine , ion transporter , nuclear magnetic resonance spectroscopy , chromatography , biochemistry , biology , mathematics , organic chemistry , combinatorics
1. A study has been made of the effects of anionic substitutions on the electrical potential difference (p.d.) and conductance characteristics of the antiluminal (peritubular) membrane of the proximal tubule of Necturus kidney. The tubular lumina were filled with oil in order to minimize potential and conductance contributions from luminal membrane and from paracellular shunt pathway. 2. Isosmotic substitutions, [A] o for [Cl] o , produced the following average changes in membrane p.d. (mV): F − +1·7, BrO 3 − +0·1, Br − ‐4·5, ClO 3 − ‐5·2, I − ‐7·9, NO 3 − ‐12·1, ClO 4 − ‐17·8, SCN − ‐25·3. 3. The amplitude of the depolarization caused by increase in K concentration (K‐depolarization) in the peritubular perfusate was found to increase during perfusion of the tissue with ClO 4 − (by 78%), SCN − (45%), I − (23%), NO 3 − (20%), Br − (16%); it decreased with F − (by 17%). 4. Comparison of membrane p.d. at peak K‐depolarization in the control state (during KCl perfusion) with that obtained in the experimental state (during KA perfusion) was found to be more reliable than determination of bi‐ionic potentials as a qualitative estimate of the permeabilities of the various anions ( P A ) relative to that of chloride ( P Cl ). 5. Study of both peak K‐depolarization p.d. and bi‐ionic potentials yielded the following sequence for halide anion permeabilities: P F > P Cl > P Br > P I . The peritubular membrane was found to be substantially more permeable to NO 3 − , ClO 4 − and SCN − than to Cl − . 6. The sequence of membrane conductances during anionic substitutions was Cl − ≃ BrO 3 − < Br − ≤ ClO 3 − < I − ≃ F − < NO 3 − < ClO 4 − < SCN − . 7. From the changes in p.d. induced by K‐depolarization, the absolute values of p.d. at peak K‐depolarization and from the changes in membrane conductance induced by anionic substitutions, it may be inferred that Br − , I − , NO 3 − , ClO 4 − and SCN − all increase P K ; and that F − increases P Na (though a smaller increase in P K cannot be excluded).