The morphological aspects of shunt-path in the epithelium of the frog skin (R.temporaria)

Cl, Voûte; Hh, Ussing

doi:10.1016/0014-4827(70)90266-1

Cited by 17 publications

(5 citation statements)

References 6 publications

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“…3-5). Our findings, based upon open-circuited conditions, are in complete agreement with those already reported (1,(15)(16)(17). We, like the above authors, feel reassured that, despite fears of fixation and osmotic artifacts, morphological correlates of ion transport are easily visualized in frog skin.…”

Section: Light Microscope Observationssupporting

confidence: 93%

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The Role of Microfilaments in Frog Skin Ion Transport

Pratley

McQuillen

1973

The Journal of Cell Biology

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Section: Light Microscope Observationssupporting

confidence: 93%

“…The ultrastructural correlates of postulated ion pump mechanisms in this tissue were first appreciated by Farquhar and Palade (4). Later other workers (1,(15)(16)(17) have shown how the size of intercellular spaces corresponds to rates of ion transport.…”

Section: Introductionmentioning

confidence: 99%

The Role of Microfilaments in Frog Skin Ion Transport

Pratley

McQuillen

1973

The Journal of Cell Biology

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“…The Na + in the slow exchanging Na + pool cannot at all, or only a little, contribute to the transepithelial Na + transport because the transepithelial Na + transport is practically in a steady state after 5-min incubation (Nielsen, 1982). Blockade of the transepithelial Na + transport results in a shrinkage of the ceils (Vofite & Ussing, 1970a), a shrinkage of the cisternae of endoplasmic recticulum (Vofite, Mollg~rd & Ussing, 1975) and in a collapse of the intercellular spaces in the isolated epithelium (Carasso, Favard, Jard & Rajerison, 1971, Vofite & Ussing, 1970b. Therefore one may suggest that the reason for the apparent discrepancy between the Na + pools might be due to the fact that the addition of amiloride results in a release of Na + from the slower exchanging cellular and extracellular compartments.…”

Section: Amiloridementioning

confidence: 99%

Effect of amiloride, ouabain and Ba++ on the nonsteady-state Na−K pump flux and short-circuit current in isolated frog skin epithelia

Nielsen

1982

J. Membrain Biol.

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Summary. Effect of amiloride, ouabain, and Ba ++ on the nonsteady-state Na-K pump flux and short-circuit current in isolated frog skin epithelia.The active Na § transport across isolated frog skin occurs in two steps: passive diffusion across the apical membrane of the cells followed by an active extrusion from the cells via the Na + -K + pump at the basolateral membrane. In isolated epithelia with a very small Na § efflux, the appearing Na+-flux in the basolateral solution is equal to the rate of the pump, whereas the short-circuit current (SCC) is equal to the active transepithelial Na § transport. It was found that blocking the passive diffusion of Na § across the apical membrane (addition of amiloride) resulted in an instantaneous inhibition of the SCC (the transepithelial Na + transport, whereas the appearing flux (the rate of the Na + -K + pump) decreased with a halftime of 1.9 min. Addition of the Na+-K + pump inhibitor ouabain (0.1raM) resulted in a faster and bigger inhibition of the appearing flux than of the SCC. Thus, by simultaneous measurement of the SCC and the appearing Na + flux one can elucidate whether an inhibitor exerts its effect by inhibiting the pump or by decreasing the passive permeability. Addition of the K ~-channel inhibitor Ba ++, in a concentration which gave maximum inhibition of the SCC, had no effect on the appearing flux (the rate of the Na-K pump) in the first 2 rain, although the inhibition of the SCC was already at its maximum.It is argued that in the short period, where the Ba ++-induced inhibition of SCC is at its maximum and the appearing flux in unchanged, the decrease in the SCC (ASCC) is equal to the net K + flux via the Na+-K + pump, and the coupling ratio (fl) of the Na +-K + pump can be calculated from the following equation t3 = SCC~= 0/'zlSCC where SCC,_ 0 is the steady-state SCC before the addition of Ba ++. Key wordsfrog skin 9 sodium flux 9 ouabain , amiloridebarium

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“…A number of morphological features, closely correlated with the functional states of the frog skin epithelium, have been described in a series of previous publications (VoGte & Ussing, 1968& Ussing, , 1970aVofite & H~inni, 1973).…”

mentioning

confidence: 91%

Quantitative relationship between active sodium transport, expansion of endoplasmic reticulum and specialized vacuoles (“scalloped sacs”) in the outermost living cell layer of the frog skin epithelium (Rana temporaria)

1975

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When an isolated frog skin (Rana temporaria) is exposed to a hydrostatic pressure difference between inside and outside bathing solutions (inside pressure higher than outside) of 20-50 cm of H2O and if under these conditions the skin is short-circuited electrically, small "vacuoles" appear light-microscopically in the outermost living cell layer in the epithelium. The number of such "vacuoles" shows a linear dependency on the rate of active sodium transport as measured by the short-circuit current. Electron-microscopically, the "vacuoles" are interpreted as previously undescribed organelles, the "scalloped sacs" which are about 0.5 mu in diameter, with a wrinkled surface and bounded by a unit membrane. This organelle is in intimate contact with sacs and tubules of smooth endoplasmic reticulum. The observed increase in the number of scalloped sacs usually is accompanied by a significant expansion of the whole system of endoplasmic reticulum. Some of the "vacuoles" seen light-microscopically must indeed be expanded cisternae of endoplasmic reticulum. The findings are discussed in light of the possibility that the scalloped sacs and the endoplasmic reticulum may be involved in active transport of sodium ions.

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The morphological aspects of shunt-path in the epithelium of the frog skin (R.temporaria)

Cited by 17 publications

References 6 publications

The Role of Microfilaments in Frog Skin Ion Transport

The Role of Microfilaments in Frog Skin Ion Transport

Effect of amiloride, ouabain and Ba++ on the nonsteady-state Na−K pump flux and short-circuit current in isolated frog skin epithelia

Quantitative relationship between active sodium transport, expansion of endoplasmic reticulum and specialized vacuoles (“scalloped sacs”) in the outermost living cell layer of the frog skin epithelium (Rana temporaria)

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