Effects of environmental conditions on mitochondrial-rich cell density and chloride transport in toad skin

✍ Scribed by O. Devuyst; V. Beaujean; J. Crabbé

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 504 KB
• Volume: 417
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00372954

✦ Synopsis

Chloride flux across amphibian skin is usually passive, yet largely conductive; previous reports have suggested that aldosterone influences this pathway. The conductive C1-pathway and its regulation were examined further, across the abdominal skin of toads (Bufo marinus) adapted to various environments. Short-circuit current (Isc), total conductance (Gt) and C1-influx (Jcl) were measured in conditions such that there was net C1movement in absence of Na § transport. In salt-deprived animals compared to salt-adapted ones, there was a significant increase in Jcl (563 vs 200 pmol cm -2 s-l), aldosteronaemia (4.2 vs 1.1 nmol/1), as well as MRC density (1458 vs 851 mm-2). After adaptation to dilute Na2SO4 compared to MgCI> Jcl (631 vs 313 pmol cm -2 s -1) as well as the density of mitochondria-rich cells (MRC) (1306 vs 710 mm -2) practically doubled, while the toads' aldosteronaemia was lower (2.4 vs 10.8 nmol/1). In all groups of toads, Jcl was matched by Iso, and there was a close correlation between Gt and Jcl (r = 0.96), which confirms the conductive nature of transepithelial CI-movement. Furthermore, the relationship between Jcl and MRC density (r = 0.75) argues in favour of a role played by MRC on CI-conductance of epithelia such as amphibian skin. As aldosterone injected for 1 week into NaCl-adapted toads did not influence MRC density and as aldosteronaemia was not correlated with CI-conductance, this hormone does not emerge as the determinant of these parameters.