Abstract |
We carried out in vivo microperfusion experiments in acid-loaded rats to characterize the adaptive response of the unidirectional components secretory flux (Jsec) and reabsorptive flux (Jreab)] of distal tubule bicarbonate reabsorption and to test the hypothesis that Jreab is dependent on bafilomycin A1-sensitive H(+)- adenosinetriphosphatase activity. During 18 h of severe acidosis there was a significant decrease in Jsec (-15 +/- 3 vs. -38 +/- 5 pmol.min-1.mm-1, P < 0.05) and a significant increase in Jreab (37 +/- 6 vs. 0 +/- 5 pmol.min-1.mm-1, P < 0.05), which was insensitive to 10(-5) M bafilomycin A1, 10(-5) M Sch-28080, and 3 mM amiloride. After 3 days of acid loading, these same inhibitors reduced Jreab by approximately 60%. However, when water flux was completely inhibited by isosmotic perfusion, a significant Jreab (15 +/- 2 pmol.min-1.mm-1) resistant to 10(-5) M bafilomycin A1 persisted, as in severe acidosis. In reabsorbing distal tubules of overnight-fasted rats, Sch-28080 elicited no inhibition, whereas bafilomycin A1 and amiloride had significant effects (28 +/- 5, 24 +/- 4, respectively, vs. 50 +/- 4 pmol.min-1.mm-1 for fasted rats, P < 0.05). Thus, although Jsec is reduced in the transition from mild to severe metabolic acidosis of 18-h duration, the predominant effect is a stimulation of bafilomycin A1-resistant Jreab.
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Authors | D Z Levine, M Iacovitti, S Buckman, D Vandorpe, V Harrison, D M Boisvert, S P Nadler |
Journal | The American journal of physiology
(Am J Physiol)
Vol. 267
Issue 5 Pt 2
Pg. F737-47
(Nov 1994)
ISSN: 0002-9513 [Print] United States |
PMID | 7977778
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Anti-Bacterial Agents
- Anti-Ulcer Agents
- Antifungal Agents
- Bicarbonates
- Imidazoles
- Macrolides
- Sch 28080
- Ammonium Chloride
- Amiloride
- bafilomycin A1
- Proton-Translocating ATPases
- Hydrochloric Acid
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Topics |
- Acclimatization
- Acidosis
(physiopathology)
- Acute Disease
- Amiloride
(pharmacology)
- Ammonium Chloride
(administration & dosage, pharmacology)
- Animals
- Anti-Bacterial Agents
(pharmacology)
- Anti-Ulcer Agents
(pharmacology)
- Antifungal Agents
(pharmacology)
- Bicarbonates
(metabolism)
- Chronic Disease
- Diet
- Fasting
- Hydrochloric Acid
(administration & dosage, pharmacology)
- Imidazoles
(pharmacology)
- In Vitro Techniques
- Infusions, Intravenous
- Kidney Tubules, Distal
(drug effects, physiology, physiopathology)
- Macrolides
- Male
- Perfusion
(methods)
- Proton-Translocating ATPases
(metabolism)
- Rats
- Rats, Sprague-Dawley
- Reference Values
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