Localization of chloride conductance to mitochondria-rich cells in frog skin epithelium

Foskett, J. Kevin; Ussing, Hans H.

doi:10.1007/bf01868818

Cited by 64 publications

(38 citation statements)

References 19 publications

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“…This conductance is not involved in the transepithelial absorption of C1 that takes place in the frog skin in vivo or in vitro under open circuit conditions. Movement of CI does not occur through the Natransporting principal cells of the epithelium (Garcia-Diaz et al, 1985;D6rge et al, 1989) but seems to be localized either in the mitochondria-rich cells (Vo~te and Meier, 1978;Foskett and Ussing, 1986;Larsen et al, 1987) or in the tight junctions between Stratum granulosum cells (Nagel, 1989;Nagel and D6rge, 1990). …”

Section: Currents"mentioning

confidence: 99%

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

1991

The Journal of General Physiology

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A B S T R A C T Whole-cell and single channel currents were studied in cells from frog (R. pipiens and R. catesbiana) skin epithelium, isolated by collagenase and trypsin treatment, and kept in primary cultures up to three days. Whole-cell currents did not exhibit any significant time-dependent kinetics under any ionic conditions used. With an external K gluconate Ringer solution the currents showed slight inward rectification with a reversal potential near zero and an average conductance of 5 nS at reversal. Ionic substitution of the external medium showed that most of the cell conductance was due to K and that very little, if any, Na conductance was present. This confirmed that most cells originate from inner epithelial layers and contain membranes with basolateral properties. At voltages more positive than 20 mV outward currents were larger with K in the medium than with Na or N-methyl-Dglucamine. Such behavior is indicative of a multi-ion transport mechanism. Wholecell K current was inhibited by external Ba and quinidine. Blockade by Ba was strongly voltage dependent, while that by quinidine was not. In the presence of high external CI, a component of outward current that was inhibited by the anion channel blocker diphenylamine-2-carboxylate (DPC) appeared in 70% of the cells. This component was strongly outwardly rectifying and reversed at a potential expected for a C1 current. At the single channel level the event most frequently observed in the cell-attached configuration was a K channel with the following characteristics: inward-rectifying I-V relation with a conductance (with 112.

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Section: Currents"mentioning

confidence: 99%

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

1991

The Journal of General Physiology

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“…However, previous studies using other techniques have localized the major transepithelial chloride currents to this cell type. Thus, the chloride currents activated by transepithelial voltage clamping are linearly correlated with the density of MR cells (Willumsen & Larsen, 1986), and with the vibrating probe technique large Cl1-dependent currents have been recorded above single MR cells (Foskett & Ussing, 1986;Katz & Scheffey, 1986). Voltage-induced Cl-current activations are associated with the swelling of MR cells (Foskett & Ussing, 1986;Larsen, Ussing & Spring, 1987), and uptake of bromide ions from the mucosal bath (D6rge, Rick, Beck & Nagel, 1988).…”

Section: Mitochondria-rich Cellsmentioning

confidence: 99%

Cyclic AMP‐and beta‐agonist‐activated chloride conductance of a toad skin epithelium.

Willumsen

Vestergaard

Larsen

1992

The Journal of Physiology

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SUMMARY1. The control by intracellular cyclic AMP and ,-adrenergic stimulation of chloride conductance was studied in toad skin epithelium mounted in a chamber on the stage of an upright microscope. Impalement of identified principal cells from the serosal side with single-barrelled conventional or double-barrelled Cl--sensitive microelectrodes was performed at x 500 magnification. For blocking the active sodium current 50 ftM-amiloride was present in the mucosal bath.2. When clamped at transepithelial potential difference V = 0 mV, the preparations generated clamping currents of 0 9 +1 tA/cm2 (mean + S.E.M.; number of observations n = 55). The intracellular potential of principal cells (Vb) was -96+2 mV with a fractional resistance of the basolateral membrane (fRb) of 0-016 + 0-003 (n = 54), and an intracellular Cl-activity of 40 + 2 mm (n = 24).3. At V = 0 mV, serosal application of a cyclic AMP analogue, dibutyryl cyclic AMP (500 /iM) or a ,-adrenergic agonist, isoprenaline (5 /tM) resulted in a sixfold increase in transepithelial Cl-conductance identified by standard 36Cl-tracer technique.4. The clamping current at V = 0 mV was unaffected by cyclic AMP (short-circuit current ISC = 0 ±+0-3 jtA/cm2, n = 16) indicating that subepidermal Cl--secreting glands are not functioning in our preparations obtained by collagenase treatment. 5. Cyclic AMP-or isoprenaline-induced chloride conductance (GC1) activation (V = 0 mV) was not reflected in membrane potential and intracellular Cl-activity in principal cells. Intracellular chloride activity was constant at ; 40 mm at membrane potentials between -90 and -100 mV. Therefore, it can be concluded that the principal cells are not contributing to activated Cl-currents.6. At V = -100 mV where the voltage-dependent chloride conductance of mitochondria-rich (MR) cells was already fully activated, GC1 was unaffected by cyclic AMP or isoprenaline. The major effect of these treatments was a rightward displacement of the MR cell-generated Gc1-V relationship along the V axis.7. Our results indicate that the fl-adrenergically controlled cyclic AMP-mediated chloride conductance is localized to the mitochondria-rich cells.MS 9518 642 N. J. WILLUMSEN, L. VESTERGAARD AND E. H. LARSEN

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“…at stadium XXI the epidermis begins to differentiate with sodium transport characteristics which are intermediate between larvae and metamorphosed specimens. Similar analogies also concern the early appearance of flask cells in Triturus alpestris which are involved in the transport of Na and Cl ions (Foskett & Ussing, 1986;Ehrenfeld et al, 1989). These cells are scarce in pedomorphic, but.abundant in metamorphosed skin.…”

Section: Discussionmentioning

confidence: 70%

Active ion transport and morphofunctional organization in the skin of the alpine newt,Triturus alpestrisduring the life cycle

Lodi

Andreone

Dore

et al. 1993

Bolletino di zoologia

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Electrophysiological techniques were used to study active ion transport across the skin in larval, pedomorphic and metamorphosed alpine newts (Triturus alpestris apuanus). Data were compared with morphological and histoenzymological studies (alkaline phosphatase -APH -) in the skin of the same animals. A short circuit current, which presumably corresponds to active sodium transport, apparently absent in larvae, develops in pedomorphic specimens during the adult epidermis differentiation process and appears to be sensitive to some extent to temperature changes. Flask cells appear early in pedomorphic forms and reveal intense APH activity, a characteristic which is also found in adult animals. Circumstantial evidence correlates APH activity with transport phenomena. These findings support the hypothesis that morphological and physiological differentiation form part of a single process occurring during metamorphosis.

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Localization of chloride conductance to mitochondria-rich cells in frog skin epithelium

Cited by 64 publications

References 19 publications

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

Cyclic AMP‐and beta‐agonist‐activated chloride conductance of a toad skin epithelium.

Active ion transport and morphofunctional organization in the skin of the alpine newt,Triturus alpestrisduring the life cycle

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