In:
American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 276, No. 6 ( 1999-06-01), p. F847-F856
Kurzfassung:
We studied the pathways for [Formula: see text] transport in basolateral membrane vesicles (BLMV) purified from rat medullary thick ascending limbs (MTAL). An inward [Formula: see text] gradient in the presence of an inside-positive potential stimulated the rate of 22 Na uptake minimally and did not induce a 22 Na overshoot, arguing against the presence of electrogenic Na + -[Formula: see text]cotransport in these membranes. An inside-acid pH gradient stimulated to the same degree uptake of 86 Rb + (a K + analog) with or without[Formula: see text]. Conversely, applying an outward K + gradient caused a modest intracellular pH (pH i ) decrease of ∼0.38 pH units/min, as monitored by quenching of carboxyfluorescein; its rate was unaffected by[Formula: see text], indicating the absence of appreciable K + -[Formula: see text]cotransport. On the other hand, imposing an inward Cl − gradient in the presence of [Formula: see text] caused a marked pH i decrease of ∼1.68 pH units/min; its rate was inhibited by a stilbene derivative. Finally, we could not demonstrate the presence of a[Formula: see text]/lactate exchanger in BLMV. In conclusion, the presence of significant Na + -, K + -, or lactate-linked[Formula: see text] transport could not be demonstrated. These and other data suggest that basolateral Cl − /[Formula: see text]exchange could be the major pathway for[Formula: see text] transport in the MTAL.
Materialart:
Online-Ressource
ISSN:
1931-857X
,
1522-1466
DOI:
10.1152/ajprenal.1999.276.6.F847
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
1999
ZDB Id:
1477287-5
