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Dynamics and density of mitochondria‐rich cells in toad skin epithelium
Author(s) -
Katz Uri,
Gabbay Shoshana
Publication year - 1995
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 - 10.1016/0248-4900(96)85279-8
Subject(s) - conductance , transepithelial potential difference , biophysics , sodium , biology , acclimatization , toad , in vivo , osmotic concentration , epithelium , medicine , anatomy , endocrinology , biochemistry , ion transporter , chemistry , botany , membrane , genetics , mathematics , microbiology and biotechnology , organic chemistry , combinatorics
Summary— The dynamics of change in mitochondria‐rich (MR) cells density in the skin epithelium of Bufo viridis was studied on skin biopsies taken in vivo , throughout experimental periods lasting up to 3 months. When the bathing solution contained Cl − , MR cells' density (D mrc ) greatly decreased. There was one exception, when the acclimation solution was KCl, D mrc in the skin increased. The rate of decrease in D mrc depended on the mode of acclimation. When bath NaCl concentration was elevated slowly in small increments, the change in D mrc was very slow. A regression line was calculated for the rate of decrease in the density of MR cells. An equation in the form of y = 1574–10.23x (where x = days; R 2 = 0.626) was obtained with bath NaCl that was elevated from 30 to 200 mmol/l, in 45 days. Oxytocin (60 mU/ml) increased sodium transport, independently and without effect on Cl − conductance. Theophylline (1 mmol/l), which leads also to elevation of cellular cAMP in contrast, increased Na + transport, but elevated Cl − conductance 3–4 times as well. Cl − conductance that is activated by transepithelial potential was much lower in skin from hyperosmotic NaCl‐acclimated toads, as compared with that in skin from tap water‐acclimated animals. Our experiments confirm that MR cells are a major pathway for Cl − conductance, as suggested earlier. However, the density of these cells in the skin epithelium of B viridis depends not only on bath NaCl concentration, but also on the mode of acclimation of the animals. Since transport functions other than g Cl reside in the amphibian skin MR cells, the density of MR cells must also depend on these functions. These functions, and the mechanisms responsible for the down and up regulation of MR cells' density, remain to be established.