Summary
Further investigations about the role of the mitochondria-rich cell (MR cell) in hormone-mediated transport regulation in the epithelium of frog skin brought the following results: Unlike toad bladder, in frog skin the spontaneous potential difference cannot be reversed when Na transport is blocked. A similar situation is obtained when in addition to transport-blockade, one applies a chemical gradient for chloride to the epithelium. Under these conditions we found that in the intact preparation as well as in the separated epithelium: (i) the reversed current (RC) is linearly related to the number of MR cells; (ii) RC is mainly carried by a passive, transcellular chloride flux inwards and (iii) RC is sensitive to nor-adrenaline (10−7 m). The beta-blocker propranolol abolishes this effect.
We propose that the MR cells are the sites of transepithelial shunt-path and that this chloride flux is transcellular. As it is hormone sensitive, it could be an important regulatory instrument for the regulation of overall salt transport (internal shorting).
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Voûte, C.L., Meier, W. The mitochondria-rich cell of frog skin as hormone-sensitive “shunt-path”. J. Membrain Biol. 40 (Suppl 1), 151–165 (1978). https://doi.org/10.1007/BF02026003
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DOI: https://doi.org/10.1007/BF02026003