Role of K+ channels in EDHF-dependent relaxation induced by acetylcholine in canine coronary artery
| Autor: | Michitaka Hibino, Yukio Toki, Takayuki Ito, Yoshihito Nakashima, Kenji Okumura, Yasumasa Fukami |
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| Rok vydání: | 1997 |
| Předmět: |
Male
Endothelium-derived hyperpolarizing factor medicine.medical_specialty Potassium Channels Charybdotoxin Vasodilator Agents In Vitro Techniques Apamin Biological Factors chemistry.chemical_compound Dogs Internal medicine Potassium Channel Blockers Animals Medicine Channel blocker 4-Aminopyridine Enzyme Inhibitors Toxins Biological biology business.industry Iberiotoxin Coronary Vessels Acetylcholine Quaternary Ammonium Compounds Vasodilation Nitric oxide synthase NG-Nitroarginine Methyl Ester Endocrinology chemistry Potassium cardiovascular system Cardiology biology.protein Female Cyclooxygenase Peptides Cardiology and Cardiovascular Medicine business medicine.drug |
| Zdroj: | Heart and Vessels. 12:287-293 |
| ISSN: | 1615-2573 0910-8327 |
| Popis: | To identify the K+ channels responsible for endothelium-derived hyperpolarizing factor (EDHF)-dependent relaxation, we studied the effects of various K+ channel blockers on acetylcholine-induced relaxation, which persists even in the presence of both an inhibitor of nitric oxide synthase and that of cyclooxygenase, in canine coronary artery rings. A nonselective K+ channel blocker, tetrabutylammonium (TBA), a large and intermediate conductance Ca2+-activated K+ channel blocker, charybdotoxin (CTX), and a voltage-dependent K+ channel blocker, 4-aminopyridine (4-AP), significantly inhibited this residual relaxation. A combined treatment with CTX and 4-AP almost completely blocked the relaxation. Neither a large (iberiotoxin) nor a small (apamin) conductance Ca2+-activated K+ channel blocker blocked the relaxation. We also investigated effects of K+ channel blockers on basal tone to determine whether or not EDHF is involved in regulating basal tone. TBA and CTX substantially raised basal tone to a greater degree in endothelium-intact preparations than in endothelium-denuded preparations. These results indicate that EDHF may exert its relaxing action through intermediate conductance Ca2+-activated and voltage-dependent K+ channels in canine coronary arteries. In addition, EDHF may play a role in maintaining basal vascular tone. |
| Databáze: | OpenAIRE |
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