| Autor: |
D F, Gray, A S, Mihailidou, P S, Hansen, K A, Buhagiar, N L, Bewick, H H, Rasmussen, D W, Whalley |
| Rok vydání: |
1998 |
| Předmět: |
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| Zdroj: |
The Journal of pharmacology and experimental therapeutics. 284(1) |
| ISSN: |
0022-3565 |
| Popis: |
Amiodarone has been shown to affect cell membrane physicochemical properties, and it may produce a state of cellular hypothyroidism. Because the sarcolemmal Na(+)-K+ pump is sensitive to changes in cell membrane properties and thyroid status, we examined whether amiodarone affected Na(+)-K+ pump function. We measured Na(+)-K+ pump current (Ip) using the whole-cell patch-clamp technique in single ventricular myocytes isolated from rabbits. Chronic treatment with oral amiodarone for 4 weeks reduced i.p. when myocytes were dialyzed with patch-pipettes containing either 10 mM Na+ or 80 mM Na+. In myocytes from untreated rabbits, acute exposure to amiodarone in vitro reduced i.p. when patch pipettes contained 10 mM Na+ but had no effect on i.p. at 80 mM Na+. Amiodarone had no effect on the voltage dependence of the pump or the affinity of the pump for extracellular K+ either after chronic treatment or during acute exposure. We conclude that chronic amiodarone treatment reduces overall Na(+)-K+ pump capacity in cardiac ventricular myocytes. In contrast, acute exposure of myocytes to amiodarone reduces the apparent Na+ affinity of the Na(+)-K+ pump. An amiodarone-induced inhibition of the hyperpolarizing Na(+)-K+ pump current may contribute to the action potential prolongation observed during treatment with this drug. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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