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| Content Provider | PubMed Central |
|---|---|
| Author | Friis, U. G. Praetorius, H. A. Knudsen, T. Johansen, T. |
| Copyright Year | 1997 |
| Abstract | The aim of this study was to investigate the effect of the Na+/K+-ATPase on the membrane potential of peritoneal mast cells isolated from male Sprague-Dawley SPF-rats. Experiments were performed at 22–26°C in the tight-seal whole-cell configuration of the patch-clamp technique by use of Sylgard-coated patch pipettes (3–6 MΩ). High-resolution membrane currents were recorded with an EPC-9 patch-clamp amplifier controlled by the ‘E9SCREEN' software. In addition, a charting programme on another computer synchronously recorded at low resolution (2 Hz) membrane potential and holding current (low-pass filtered at 500 Hz). Na+/K+-ATPase activity was measured as the ouabain-sensitive change in the zero-current potential. The zero-current potential in rat peritoneal mast cells measured 2 min after obtaining whole-cell configuration amounted to 1.7±2.5 mV (n=21). Ouabain (5 mM), a Na+/K+-ATPase-inhibitor, had only a very minor effect upon the membrane potential under resting conditions (n=3). When mast cells were superfused with nominal calcium-free external solution, the cells hyperpolarized (Δ mV: 20.2±3.8 mV (n=5)). In addition, when the mast cells were preincubated in nominal calcium-free external solution for 12±1.6 min before whole-cell configuration, the membrane potential amounted to −53.7±9.8 mV (n=8). A subsequent superfusion with ouabain (5 mM) depolarized the membrane potential (ouabain-sensitive hyperpolarization (Δ mV): 23.0±8.4 mV (n=8)). A high intracellular concentration of Na+ ([Na+]i) (26.6 mM) also resulted in hyperpolarization (Δ mV: 20.2±9.1 mV (n=7)), but only when ATP was present. A subsequent superfusion with ouabain (5 mM) repolarized these cells to −1.2±14 mV (ouabain-sensitive hyperpolarization (Δ mV): 19.7±7.7 mV (n=7)). The size of the [Na+]i-dependent hyperpolarization was dose-dependent. Low [Na+]i (1 mM) had no effect on membrane potential and these cells were unaffected by superfusion with calcium-free external solution. These data thus directly confirm that the stimulant effect of calcium-free external solutions on the ouabain-sensitive changes in the zero-current potential, and hence the Na+/K+-ATPase, is mediated through [Na+]i and that the activity of the Na+/K+-ATPase can have an important influence on the resting membrane potential in rat peritoneal mast cells. |
| Related Links | http://dx.doi.org/10.1038/sj.bjp.0701414 |
| Ending Page | 604 |
| Page Count | 6 |
| Starting Page | 599 |
| File Format | |
| ISSN | 00071188 |
| Journal | British Journal of Pharmacology |
| Issue Number | 4 |
| Volume Number | 122 |
| Language | English |
| Publisher Date | 1997-10-01 |
| Access Restriction | Open |
| Subject Keyword | Pharmacology Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Pharmacology |
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