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The role of mitochondria‐rich cells in the chloride current conductance across toad skin
Author(s) -
Katz U.,
Driessche W.,
Scheffey C.
Publication year - 1985
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1985.tb00433.x
Subject(s) - toad , chloride , biophysics , sodium , biology , frog skin , transepithelial potential difference , conductance , extracellular , theophylline , biochemistry , microbiology and biotechnology , anatomy , chemistry , endocrinology , ion transporter , membrane , mathematics , organic chemistry , combinatorics
In early studies of salt transport across frog and toad skin, it was assumed that chloride movement is extracellular. However, later studies suggested that chloride movement is largely transcellular. Chloride transport across toad skin is greatly diminished in skins of salt‐acclimated toads (Bufo viridis) and was correlated with the number of mitochondria‐rich (m.r.) cells in the epithelium. The activated chloride conductance could be recovered upon in vitro incubation with theophylline. It was found that the short‐circuit current (Isc) and the chloride conductance (Gcl) in toad skin could be separated experimentally by selective use of synthetic oxytocin (Syntocinon) or theophylline, and by substituting impermeable anions for chloride. With the use of the vibrating probe we demonstrated directly that chloride‐dependent peak currents are localized only over m.r. cells, under hyperpolarized (V = −100 mV) conditions. It is concluded that the m.r. cells form the principal site for passive chloride movement across amphibian skin. This cellular pathway is regulated through a cyclic AMP‐mediated process. It is suggested that the spatial separation of the sodium and chloride channels is essential to maintain the granulosum cells which are engaged in sodium transport hyperpolarized, and thus providing the driving force for the sodium entry into the cells.