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Effect of prolonged saline‐exposure on sodium transport across frog‐skin
Author(s) -
Hornby R.,
Thomas S.
Publication year - 1969
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1969.sp008696
Subject(s) - saline , sodium , chemistry , zoology , physiological saline , rana , endocrinology , biology , organic chemistry
1. Differences in Na transport between skins from Rana temporaria and R. esculenta maintained for up to several weeks in water or 0·7% saline (0·7 g NaCl in 100 ml. H 2 O), with and without daily injections of 4% saline (4 g NaCl in 100 ml. H 2 O), were measured, in vitro . 2. In saline‐treated skins, the following changes were found: ( a ) An increased Na content. ( b ) A consistent decrease in short‐circuit current ( I sc ). ( c ) An increased d.c. resistance, R , the consistency of which varied with the anion content of the Ringer solution. ( d ) A highly significant fall in Na influx, accounting for the reduced I sc ; a small reduction in Na efflux was not significant, statistically. ( e ) The Pitressin‐induced increment in I sc was usually considerably lower compared with that in water‐exposed skins; considered relative to the pre‐Pitressin values, however, there were no clear differences. ( f ) By calculation from the changes in resistance ( R ) caused by replacement of outer Na 2 SO 4 Ringer by K 2 SO 4 Ringer solution, I. E 0 , the electromotive force of the active sodium transport system, was moderately, but significantly, reduced, II. R shunt , the shunt path resistance, was moderately, but significantly, increased, and III. R ser , the series path resistance, was considerably, and highly significantly, increased. ( g ) K influx from outer K 2 SO 4 Ringer solution was reduced. 3. Differences between skins from water‐exposed and saline‐treated frogs persisted, in vitro , despite the occurrence of anionic‐dependent acute changes after mounting in Ringer solution. 4. There were seasonal changes in I sc , and in the effects of saline treatment. 5. The findings are discussed in terms of decreased permeability of outer barriers to ion‐diffusion, and reduced activity of a Na pump.