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Wakabayashi, I; Kukovetz, WR; Groschner, K.
NH4Cl-induced contraction of porcine coronary artery involves activation of dihydropyridine-sensitive Ca2+ entry.
Eur J Pharmacol. 1996; 299(1-3):139-147
Doi: 10.1016/0014-2999(95)00853-5
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- Co-authors Med Uni Graz
- Groschner Klaus
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- Abstract:
- The role of voltage-dependent, dihydropyridine-sensitive Ca2+ channels in NH4Cl-induced vasoconstriction was investigated in isolated porcine coronary arteries by measuring in parallel isometric tone and 45Ca2+ uptake. NH4Cl (10-80 mM) concentration dependently induced tonic contractions which were preceded by a time lag of several minutes. Contractile responses to high (60 mM) as well as low (25 mM) concentrations of NH4Cl were markedly inhibited by 1 microM nifedipine or removal of extracellular Ca2+. The contractile effect of 25 mM NH4Cl was substantially enhanced by increasing extracellular K+ to 14.7 mM or by pretreatment of coronary arteries with either 5 mM tetraethylammonium chloride or 0.1 microM 1,4-dihydro- 2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)-phenyl]-3-pyridine carboxylic acid methyl ester (BAY K8644). NH4Cl (60 mM) significantly increased 45Ca2+ uptake with a lag time of more than 5 min. The increase in 45Ca2+ uptake induced by 60 mM NH4Cl was abolished in the presence of 1 microM nifedipine. Although NH4Cl (25 mM) did not detectably stimulate 45Ca2+ uptake in normal K+ solution, it significantly augmented 45Ca2+ uptake when extracellular K+ was increased to 14.7 mM. Furthermore, NH4Cl (20 mM) potentiated histamine-induced contraction of coronary arteries. This potentiating effect of NH4Cl was completely antagonized by nifedipine. Our results suggest an involvement of nifedipine-sensitive Ca2+ channels in NH4Cl-induced vasoconstriction of porcine coronary artery.
- Find related publications in this database (using NLM MeSH Indexing)
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester - pharmacology
- Ammonium Chloride - pharmacology
- Animals -
- Calcium - metabolism
- Calcium Channel Agonists - pharmacology
- Calcium Channel Blockers - pharmacology
- Calcium Channels - drug effects
- Coronary Vessels - drug effects Coronary Vessels - metabolism
- Dose-Response Relationship, Drug -
- Nifedipine - pharmacology
- Swine -
- Tetraethylammonium Compounds - pharmacology
- Vasoconstriction -
- Find related publications in this database (Keywords)
- NH4Cl
- vasoconstriction
- coronary artery
- intracellular pH