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Pathways for HCO-3 exit across the basolateral membrane in rat thick limbs
- Source :
- Europe PubMed Central
-
Abstract
- 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 of22Na uptake minimally and did not induce a22Na 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 of86Rb+(a K+analog) with or without[Formula: see text]. Conversely, applying an outward K+gradient caused a modest intracellular pH (pHi) 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 pHidecrease 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.
- Subjects :
- Male
Kidney Cortex
Physiology
Bicarbonate
Rats, Sprague-Dawley
chemistry.chemical_compound
medicine
Animals
Membrane vesicle
Lactic Acid
Anion exchanger
Epithelial polarity
Kidney
Chemistry
Vesicle
Sodium-Bicarbonate Symporters
Hydrogen-Ion Concentration
Rubidium
Rats
Bicarbonates
medicine.anatomical_structure
Kidney Tubules
Biochemistry
Biophysics
Loop of Henle
Carrier Proteins
Acids
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Europe PubMed Central
- Accession number :
- edsair.doi.dedup.....3231697d4822a11e3c3170c03cbd263f