ISSN:
1432-1424
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The effect of changes in Cl concentration in the external and/or serosal bath on Cl transport across short-circuited frog skin was studied by measurements of transepithelial Cl influx (J 13 Cl ) and efflux (J 31 Cl ), short-circuit current, transepithelial potential, and conductance (G m).J 13 Cl as well asJ 31 Cl were found to have a saturating component and a component which is apparently linear with Cl concentration. The linear component ofJ 31 Cl appears only upon addition of Cl to external medium, and about 3/4 of this component does not contribute toG m. The saturating component ofJ 31 Cl is only 5% of totalJ 31 Cl with 115mm Cl in the serosal medium. Replacement of 115mm Cl− in external medium by SO 4 = , NO 3 − , HCO 3 − or I− results in 87–97% reduction ofJ 31 Cl , whereas replacement with Br− has no effect. As external Cl concentration is raised in steps from 2 to 115mm,J 13 Cl andJ 31 Cl increase by the same amount butJ 13 Cl is persistently 0.15 μeq/cm2 hr larger thanJ 31 Cl . These results indicate that at least 3/4 of linear components ofJ 13 Cl andJ 31 Cl proceed via an exchange diffusion mechanism which seems to be located at the outer cell border. The saturating component ofJ 13 Cl is involved in active Cl transport in an inward direction, and there is evidence suggesting that Cl uptake across outer cell border, which proceeds against an electrochemical gradient, is electroneutral but not directly linked to Na.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01869355
