Induced alterations in calcium uptake rate in normoxic rat proximal tubules
| Autor: | D. Bunnachak, Jacob K. Joseph, Eric D. Wieder, Jack F.M. Wetzels, Luis Yu, Andreas Kribben, A. R. P. Almeida, Robert W. Schrier, Thomas J. Burke |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty Cell Membrane Permeability Potassium Sodium chemistry.chemical_element In Vitro Techniques Calcium Critical Care and Intensive Care Medicine Ouabain Membrane Potentials protection by acidosis and glycine. [Mechanisms of ischemic cell injury in the proximal tubule] Kidney Tubules Proximal Rats Sprague-Dawley Valinomycin chemistry.chemical_compound Adenosine Triphosphate Amphotericin B Internal medicine medicine Extracellular Animals Ion transporter Kidney Ionophores L-Lactate Dehydrogenase business.industry General Medicine Rats medicine.anatomical_structure Endocrinology chemistry Nephrology business het beschermende effect van acidose en glycine. [Mechanismen van ischemische celbeschadiging in de proximale tubulus] medicine.drug |
| Zdroj: | Renal Failure, 17, 503-515 Renal Failure, 17, pp. 503-515 |
| ISSN: | 0886-022X |
| Popis: | This study is well-oxygenated, freshly isolated rat proximal tubules (RPT), examined the effects of several drugs that alter the transmembrane K+ and Na+ gradients across cell membranes, including valinomycin (VAL), amphotericin B (AMPHO), and ouabain (OUAB). The effects of high extracellular potassium chloride (KCl) concentrations (45 mM) and low extracellular sodium concentration (100mM) were also studied. After 10 min of drug exposure Ca2+ uptake rate (nmol/mg/min) increased from 2.7 to 3.8 with VAL (p.02), from 2.9 to 3.7 with AMPHO (p.05), from 3.6 to 4.1 with OUAB (p.05), and from 3.2 to 4.8 with 45 mM KCl (p.001). Ca2+ uptake rate was sustained at these high levels at 20 min in all treated RPT except those exposed to OUAB. LDH release averaged less than 15% in control tubules and did not increase significantly except in RPT treated with VAL, where LDH release at 10 min was 48% and at 20 min was 57% (both p.001). Of importance, only in VAL-treated RPT did ATP decrease to low levels (6.7 nmol/mg in control to 2.0 +/- 0.3 nmol/mg in VAL, p.001). Treatment with verapamil reduced Ca2+ uptake rates at 10 min in VAL-treated RPT (from 3.8 to 3.1, p.02, in AMPHO-treated RPT (from 3.8 to 3.1 p.001), in OUAB-treated tubules (from 4.0 to 3.4, p.01), and in KCl-treated RPT (from 3.7 to 3.2, p.01). These results indicate that acute changes in the transmembrane ion gradient in RPT are accompanied by increased Ca2+ uptake rates. Ca2+ uptake rates are also increased during O2 deprivation in RPT, a situation in which the transmembrane ion gradient is likewise altered. The increased Ca2+ uptake rate observed in the present study and during hypoxia may have a common basis, that is, altered transmembrane ion gradients or some function thereof. |
| Databáze: | OpenAIRE |
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