Anion and cation channels in the basolateral membrane of rabbit parietal cells

Abstract

Ion channels in the basolateral membrane of rabbit parietal cells in isolated gastric glands were studied by the patch clamp technique. Whole-cell current-clamp recordings showed that the membrane potential (Em) changed systematically as a function of the chloride concentrations of the basolateral bathing solution ([Cl-]0), and of the pipette (intracellular) solution. The relationship between Em and [Cl-]0 was not affected by additions of histamine, dibutyryl-cAMP, 4-acetoamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and diphenylamine-2-carboxylate. The whole-cell Cl- conductance was insensitive to voltage. In cell-attached and cell-free patch membranes, however, single Cl- channel opening events could not be observed. The value of Em depended little on the basolateral K+ concentration, but inward-rectifier K+ currents were observed in the whole-cell configuration, activated by hyperpolarizing pulses and inhibited by extracellular Ba2+. In cell-attached and cell-free patches, openings of single inward-rectifier K+ channels and non-selective cation channels were infrequently recorded. Neither cAMP nor Ca2+ activated these cation channels. The single K+ channel conductance was about 230 pS under the symmetrical high K+ conditions and was inhibited by intracellular tetraethylammonium ions (TEA). The non-selective cation channel had a voltage-independent single conductance of 22 pS and was not inhibited by TEA.

Arachidonic acid and prostaglandin E2 activate small‐conductance Cl‐ channels in the basolateral membrane of rabbit parietal cells.

“…The melting point of the purified NPPB was 170- potential by 37 8±+15 mV (5) (from -4 + 0± 8 (5) to 33 8+0 7 mV (5)), even in the presence of 7 mM-K+. This value is in good agreement with a value calculated from the Goldman equation (36 3 mV) taking into account the permeability coefficient of aspartate ions (Sakai et al 1989a). Essentially the same results were obtained from singly isolated parietal cells (data not shown).…”

“…Small-conductance Cl-channels in the basolateral membrane As described previously (Sakai et al 1989a), we could record whole-cell Clcurrents ( Fig. 1) but not single open-closed events of the Cl-channel in cell-attached and excised patches of the rabbit parietal cell membrane.…”

“…In a previous study, an electroconductive Cl-pathway was found in the basolateral membrane of rabbit parietal cells (Sakai, Okada, Morii & Takeguchi, 1989a). Single Cl-channel open-closed events could not be observed in excised and cell-attached patch membranes.…”

Small‐conductance Cl‐ channels in rabbit parietal cells activated by prostaglandin E2 and inhibited by GTP gamma S.

“…The 140choline+-146Cl-bathing solution contained (in mM): 140 choline chloride, 2 MgCl2, 1 CaCl2, 10 Hepes. Both bathing solutions contained 100 yM ouabain (Sakai et al 1989) and were adjusted to pH 7 3 with KOH or Tris. The 133K+-13Cl-pipette solution contained (in mM): 133 potassium aspartate, 7 NaCI.…”

“…An important physiological role of the sub-pS Cl-channel is to dominate the cell membrane potential, whereas K+ channels which are present in the basolateral membrane do not significantly contribute to the membrane potential (Sakai, Okada, Morii & Takeguchi, 1989;. This Cl-channel is activated by arachidonic acid and prostaglandin E2 ).…”