Modulation of arterial Na+-K+-ATPase-induced [Ca2+]i reduction and relaxation by norepinephrine, ET-1, and PMA
| Autor: | Juan Tamargo, Francisco Perez-Vizcaino, Angel Cogolludo |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Male
medicine.medical_specialty Cytoplasm Fura-2 Physiology Swine Potassium Chloride Norepinephrine (medication) chemistry.chemical_compound Norepinephrine Physiology (medical) Internal medicine medicine Animals Vasoconstrictor Agents Na+/K+-ATPase Protein kinase C Membrane potential Endothelin-1 Osmolar Concentration Staurosporine Endothelin 1 Mesenteric Arteries Vasodilation Endocrinology chemistry Vasoconstriction Phorbol Tetradecanoylphorbol Acetate Calcium Sodium-Potassium-Exchanging ATPase Cardiology and Cardiovascular Medicine Intracellular medicine.drug |
| Zdroj: | The American journal of physiology. 276(2) |
| ISSN: | 0002-9513 |
| Popis: | Na+-K+-ATPase plays a major role in regulating membrane potential and vascular tone. We analyzed the modulation by norepinephrine (NE), endothelin-1 (ET-1), and phorbol 12-myristate 13-acetate (PMA) of Na+-K+-ATPase-induced cytoplasmic free Ca2+concentration ([Ca2+]i) reduction and relaxation in isolated endothelium-denuded piglet mesenteric arteries. KCl (0.2–8.8 mM)-induced [Ca2+]ireduction and relaxation in arteries incubated in K+-free solution were used as functional indicators of Na+-K+-ATPase activity. KCl-induced relaxations after exposure to K+-free solution were associated with a reduction in [Ca2+]i, as measured by fura 2 fluorescence. However, KCl reduced [Ca2+]ibelow resting values, whereas force was reduced to near resting values. NE, ET-1, and PMA inhibited the relaxant effects of KCl, and this effect was attenuated by the protein kinase C inhibitor staurosporine but not by the phospholipase A2inhibitor quinacrine. However, ET-1 and PMA potentiated the [Ca2+]i-reducing effect of KCl. In conclusion, ET-1, PMA, and NE are functional inhibitors of Na+-K+-ATPase activity in endothelium-denuded piglet mesenteric arteries, even when the direct effect on the enzyme activity may be stimulatory rather than inhibitory. This can be explained because ET-1, PMA, and NE induce Ca2+sensitization for smooth muscle contraction, and therefore relaxations do not parallel the reductions in [Ca2+]iafter the activation of Na+-K+-ATPase. |
| Databáze: | OpenAIRE |
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