Insulin action on electrophysiological properties of apical and basolateral membranes of frog skin

Schoen, Howard F.; Erlij, David

doi:10.1152/ajpcell.1987.252.4.c411

Cited by 15 publications

(14 citation statements)

References 25 publications

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“…This finding suggests the possibility that insulin also increases the exocytotic delivery of membranes to the basolateral border as well as the apical membrane. Exocytotic addition of membranes could be the mechanism for the increased basolateral membrane conductance caused by insulin (Schoen & Erlij, 1987) and could be responsible as well for the increased rate of Na+ pumping proposed by Walker et al (1984). The large effect of insulin on Cb, an increase of nearly 60%, compared with the more modest increase in Ca, of about 10%, may appear surprising at first; however, it is not completely without precedent.…”

Section: Discussionmentioning

confidence: 99%

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Effect of insulin on area and Na+ channel density of apical membrane of cultured toad kidney cells.

Erlij

Smet

Driessche

1994

The Journal of Physiology

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1. The stimulation of transepithelial Na+ transport caused by insulin in A6 cultured toad kidney cells was investigated by determination of membrane capacitance (Cm), short circuit current (Isc) and current fluctuation analysis. Values of Cm are proportional to membrane area while blocker‐induced current fluctuation analysis provides an estimate of the number of active amiloride‐sensitive Na+ channels in the apical membrane. 2. Insulin simultaneously increased Cm, Isc and Gt (transepithelial conductance) in epithelia incubated with Na(+)‐containing solutions on both sides. 3. Analysis of 6‐chloro‐3,5‐diaminopyrazine‐2‐carboxamide (CDPC)‐induced noise showed that insulin increased the number of active Na+ channels in the apical membrane, without altering the single channel current. 4. When nystatin was used to permeabilize the apical membrane the impedance data revealed the presence of a second time constant. Analysis of these data indicated that the basolateral membrane capacitance (Cb) is much larger than the apical membrane capacitance (Ca). Insulin administered to nystatin‐treated epithelia increased the values for both capacitances. 5. We suggest that the stimulation of transepithelial Na+ transport caused by insulin may be associated with the exocytotic delivery of transporters to the apical membrane.

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Section: Discussionmentioning

confidence: 99%

“…The fact that membrane potential is not depolarized when apical membrane Na+ conductance increases could be due to increased basolateral K+ conductance. Indeed, Schoen & Erlij (1987) found that insulin increases basolateral membrane conductance in the frog skin.…”

Section: Discussionmentioning

confidence: 99%

Effect of insulin on area and Na+ channel density of apical membrane of cultured toad kidney cells.

Erlij

Smet

Driessche

1994

The Journal of Physiology

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“…The concerted action of these two membrane proteins results in transepithelial sodium absorption from the urinary to the extracellular space. The activity of ENaC is usually the ratelimiting step of the sodium transport and is under the control of various hormones, mainly aldosterone (2,4,7,10,13,16,41), insulin (3,13,23,35,40), and antidiuretic hormone (22,46). The signal transduction pathways linking each of the hormone receptors to ENaC are still under investigation.…”

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confidence: 99%

Phosphatidylinositol 3,4,5-trisphosphate: an early mediator of insulin-stimulated sodium transport in A6 cells

Markadieu

Bléro

Boom

et al. 2004

American Journal of Physiology-Renal Physiology

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lin stimulates sodium transport across A6 epithelial cell monolayers. Activation of phosphatidylinositol 3-kinase (PI 3-kinase) was suggested as an early step in the insulin-stimulated sodium reabsorption (Ref. 35). To establish that the stimulation of the PI 3-kinase signaling cascade is causing stimulation of apical epithelial Na channel, we added permeant forms of phosphatidylinositol (PI) phosphate (P) derivatives complexed with a histone carrier to A6 epithelium. Only PIP 3 and PI(3,4)P2 but not PI(4,5)P2 stimulated sodium transport, although each of them penetrated into A6 cell monolayers as assessed using fluorescent permeant phosphoinositides derivatives. By Western blot analysis of A6 cell extracts, the inositol 3-phosphatase PTEN and the protein kinase B PKB were both detected. To further establish that the stimulation of sodium transport induced by insulin is related to PIP 3 levels, we transfected A6 cells with human PTEN cDNA and observed a 30% decrease in the natriferic effect of insulin. Similarly, the increase in sodium transport observed by addition of permeant PIP 3 was also reduced by 30% in PTEN-overexpressing cells. PKB, a main downstream effector of PI 3-kinase, was phosphorylated at both Thr 308 and Ser 473 residues upon insulin stimulation of the A6 cell monolayer. PKB phosphorylation in response to insulin stimulation was reduced in PTEN-overexpressing cells. Permeant PIP 3 also increased PKB phosphorylation. Taken together, the present results establish that the D-3-phosphorylated phosphoinositides PIP3 and PI(3,4)P 2 mediate the effect of insulin on sodium transport across A6 cell monolayers.

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“…The increase in the initial rate of [ 3 H]ouabain binding can be due to either a change in the ouabain-binding kinetics or in the total number of pumps available for binding in the cell surface. A change in the kinetics of [ 3 H]ouabain binding could be related to the stimulation of I sc because insulin increases Na + entry across the apical border of tight epithelia [26]. The increased sodium delivery would in turn modify the apparent affinity of the Na + -K + -ATPase for ouabain by shifting the E 1 /E 2 conformation ratio [13,27].…”

Section: Effects Of Insulin On the Initial Rate Of [ 3 H]ouabain Bindmentioning

confidence: 99%

“…Insulin stimulates transepithelial Na + transport in a number of renal epithelia types [3,8,16,17]; this action is most likely responsible for the Na + -retaining effect of the hormone [4,21] and involves increases in both apical and basolateral membrane permeabilities [6,19,26]. In addition, the activity of the epithelial Na + -K + -ATPase appears to be increased by insulin [9].…”

Section: Introductionmentioning

confidence: 99%

Insulin effects on ouabain binding in A6 renal cells

Smet

Erlij

Driessche

1997

Pfl�gers Archiv European Journal of Physiology

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The effects of insulin on the Na+-K+-ATPase pump of the basolateral membrane of tight epithelia were evaluated by measuring transepithelial transport and [3H]ouabain binding in cultured A6 kidney cells. [3H]Ouabain binding in epithelia incubated in either K+-containing or K+-free solutions was measured. Insulin induced increases in transepithelial sodium transport, as measured by the short-circuit current (Isc), and in the initial rate of [3H]ouabain binding determined when the preparation was bathed in K+-containing solutions. However, when initial [3H]ouabain binding in tissues incubated in K+-free solutions was measured the stimulation of the initial rate of [3H]ouabain binding caused by insulin was markedly reduced. Incubating the apical side of the epithelium with either amiloride or Na+-free solutions also reduced or abolished the increase in the initial rate of [3H]ouabain binding caused by insulin. Equilibrium binding measurements showed that insulin did not increase the maximum number of [3H]ouabain-binding sites in tissues incubated with either normal K+ or K+-free solutions. These results indicate that the increase in the initial rate of [3H]ouabain binding under transporting conditions is due to an effect on the binding kinetics of ouabain, probably related to an increased rate of Na+ entry, rather than to an increase in the number of Na+-K+-ATPases in the basolateral membrane. Cycloheximide inhibited both the increase in Isc and the increase in the initial rate of [3H]ouabain binding caused by insulin in epithelia incubated in K+-containing solutions. However, cycloheximide was without effect on the initial rate of [3H]ouabain binding in insulin-treated tissues incubated in K+-free solution. This finding suggests that the cycloheximide-sensitive step of the action of insulin is related to Na+ delivery to the pump.

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Insulin action on electrophysiological properties of apical and basolateral membranes of frog skin

Cited by 15 publications

References 25 publications

Effect of insulin on area and Na+ channel density of apical membrane of cultured toad kidney cells.

Effect of insulin on area and Na+ channel density of apical membrane of cultured toad kidney cells.

Phosphatidylinositol 3,4,5-trisphosphate: an early mediator of insulin-stimulated sodium transport in A6 cells

Insulin effects on ouabain binding in A6 renal cells

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