Characterization of the basolateral membrane conductance of Necturus urinary bladder.

Demarest, J. R.; Finn, Arthur L.

doi:10.1085/jgp.89.4.541

Cited by 13 publications

(18 citation statements)

References 47 publications

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“…The ratio of resistances is also unchanged for several minutes after amiloride, which shows that basolateral membrane resistance initially increases with the same time course as that of the apical membrane.) Second, Ba", which blocks K+ conductance in a wide variety of tissues, including epithelia (Kirk et al, 1980 ;Latorre and Miller, 1983;Wills, 1985;Demarest and Finn, 1987), was found in the present study to block volume regulation . In keeping with this notion, Lewis et al (1985) have recently identified apparent volume-sensitive changes in basolateral membrane electromotive force and conductance in toad urinary bladder.…”

Section: Basolateral Membrane Solute Transport and Intracellular Ca ++supporting

confidence: 56%

“…K' that is pumped into the cell is recycled across the basolateral membrane by electrodiffusion since the electromotive force in this, as in other, tight epithelia is primarily determined by K'. However, the membrane is not a perfect K' electrode, and, in fact, a Clconductance has been demonstrated in several tissues (Lewis et al, 1978;Wills et al, 1979;Thompson et al, 1982;Schultz et al, 1984;Demarest and Finn, 1987). Also incorporated into the model are features by which coordination of transport activities at the two membranes is achieved (see reviews by Taylor and lumen apical membrane blood FIGURE 1 .…”

Section: Introductionmentioning

confidence: 99%

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Interactions of sodium transport, cell volume, and calcium in frog urinary bladder.

Davis¹,

Finn²

1987

The Journal of General Physiology

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The volume of individual cells in intact frog urinary bladders was determined by quantitative microscopy and changes in volume were used to monitor the movement of solute across the basolateral membrane . When exposed to a serosal hyposmotic solution, the cells swell as expected for an osmometer, but then regulate their volume back to near control in a process that involves the loss of KCI . We show here that volume regulation is abolished by Ba++, which suggests that KCl movements are mediated by conductive channels for both ions. Volume regulation is also inhibited by removing Ca" from the serosal perfusate, which suggests that the channels are activated by this cation . Previously, amiloride was observed to inhibit volume regulation: in this study, amiloride-inhibited, hyposmotically swollen cells lost volume when the Ca" ionophore A23187 was added to Ca"-replete media. We attempted to effect volume changes under isosmotic conditions by suddenly inhibiting Na' entry across the apical membrane with amiloride, or Na' exit across the basolateral membrane with ouabain . Neither of these Na' transport inhibitors produced the expected results . Amiloride, instead of causing a decrease in cell volume, had no effect, and ouabain, instead of causing cell swelling, caused cell shrinkage . However, increasing cell Ca" with A23187, in both the absence and presence of amiloride, caused cells to lose volume, and Ca'-free Ringer's solution (serosal perfusate only) caused ouabain-blocked cells to swell. Finally, again under isosmotic conditions, removal of Na' from the serosal perfusate caused a loss of volume from cells exposed to amiloride . These results strongly suggest that intracellular Ca" mediates cell volume regulation by exerting a negative control on apical membrane Na' permeability and a positive control on basolateral membrane K`permeability . They also are compatible with the existence of a basolateral Na/Ca" exchanger .

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Section: Basolateral Membrane Solute Transport and Intracellular Ca ++supporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Interactions of sodium transport, cell volume, and calcium in frog urinary bladder.

Davis¹,

Finn²

1987

The Journal of General Physiology

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“…"Leaky" epithelia have transepithelial resistances <300 f~ 9 cm 2 while "tight" epithelia have resistances >300 f~ 9 cm 2 (Diamond, 1979). The meafi transepithelial resistance in lingual epithelium from Necturus was 2000 -+ 1400 f~ 9 cm 2 (N = 24; mean -+ SD) when measured in symmetrical solutions of amphibian physiological saline (APS), comparable to that in urinary bladder from this species (Demarest & Finn, 1987a). This classifies Necturus lingual epithelium as tight.…”

Section: Resultsmentioning

confidence: 83%

“…The seasonal variation of the TEA-sensitive channels on the basolateral membrane was unexpected but not unprecedented. For example, the urinary bladder of Necturus also exhibits seasonal variations (Karnaky et al, 1984;Demarest & Finn, 1987a).…”

Section: Discussionmentioning

confidence: 99%

Distribution of ion channels on taste cells and its relationship to chemosensory transduction

Roper

McBride

1989

J. Membrain Biol.

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The presence and regional localization of voltage-gated ion channels on taste cells in Necturus maculosus were studied. Lingual epithelium was dissected from the animal and placed in a modified Ussing chamber such that individual taste cells could be impaled with intracellular microelectrodes and the chemical environment of the apical and basolateral membranes of cells could be strictly controlled. That is, solutions bathing the mucosal and serosal surfaces of the epithelium could be exchanged independently and the effects of pharmacological agents could be tested selectively on the apical or basolateral membranes of taste cells. In the presence of amphibian physiological saline, action potentials were elicited by passing brief depolarizing current pulses through the recording electrode. Action potentials provided a convenient assay of voltage-gated ion channels. As in other excitable tissues, blocking current through Na+, K+, or Ca2+ channels had predictable and consistent effects on the shape and magnitude of the action potential. A series of experiments was conducted in which the shape and duration of regenerative action potentials were monitored when the ionic composition was altered and/or pharmacological blocking agents were added to the mucosal or to the serosal chamber. We have found the following: (i) voltage-gated K+ channels (delayed rectifier) are found predominately, if not exclusively, on the chemoreceptive apical membrane; (ii) voltage-gated Na+ and Ca2+ channels are found on the apical (chemoreceptive) and basolateral (synaptic) membranes; (iii) there is a K+ leak channel on the basolateral membrane which appears to vary seasonally in its sensitivity to TEA. The nonuniform distribution of voltage-gated K+ channels and their predominance on the apical membrane may be important in taste transduction: alterations in apical K+ conductance may underlie receptor potentials ellicted by rapid stimuli.

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“…6 in Schultz, 1979). Using Necturus urinary bladder, Demarest and Finn (1987) found that the apical membrane potential became 40 mV more negative (i.e., hyperpolarized) upon doubling the paracellular resistance. In summary, the potential profiles across epithelial cells depends on the paracellular pathway(s) resistance and selectivity (Reuss, 1979;Schultz, 1979).…”

Section: Paracellular Pathways Between Taste Cellsmentioning

confidence: 97%

Transcellular and paracellular pathways in lingual epithelia and their influence in taste transduction

Simon

Holland

Benos

et al. 1993

Microscopy Res & Technique

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The lingual epithelium is innervated by special sensory (taste) and general sensory (trigeminal) nerves that transmit information about chemical stimuli introduced into the mouth to the higher brain centers. Understanding the cellular mechanisms involved in eliciting responses from these nerves requires a detailed understanding of the contributions of both the paracellular and transcellular pathways. In this paper we focus on the contribution of these 2 pathways to the responses of salts containing sodium and various organic anions in the presence and absence of amiloride. Electrophysiological recordings from trigeminal nerves, chorda tympani nerves, and isolated lingual epithelia were combined with morphological studies investigating the location (and permeability) of tight junctions, the localization of amiloride-inhibitable channels, and Na-K-ATPase in taste and epithelial cells. Based on these measurements, we conclude that diffusion across tight junctions can modulate chorda tympani and trigeminal responses to sodium-containing salts and rationalize the enhancement of taste responses to saccharides by NaCl.

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Characterization of the basolateral membrane conductance of Necturus urinary bladder.

Cited by 13 publications

References 47 publications

Interactions of sodium transport, cell volume, and calcium in frog urinary bladder.

Interactions of sodium transport, cell volume, and calcium in frog urinary bladder.

Distribution of ion channels on taste cells and its relationship to chemosensory transduction

Transcellular and paracellular pathways in lingual epithelia and their influence in taste transduction

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