Mechanisms mediating the vasorelaxing action of eugenol, a pungent oil, on rabbit arterial tissue.
The inhibitory actions of eugenol on intracellular Ca2+ concentration ([Ca2+]i) and the contractions induced by excess extracellular K+ concentration ([K+]o) in rabbit thoracic aorta were investigated. Application of excess [K+]o solution (30-90 mM) produced contraction and increased the intensity of the Ca2+ fluorescence signal. Pretreatment with eugenol (> or =0.1 mM) reduced both the amplitude of contraction and the intensity of the Ca2+ fluorescence signal, but the contraction was more strongly affected than the [Ca2+]i. Application of eugenol (0.3 mM) to tissue precontracted by 90 mM [K+]o solution (immediately after the removal of the 90 mM [K+]o solution) slowed the decay of the [Ca2+]i signal, but it did not change the rate of relaxation. Carbonyl cyanide m-chlorophenylhydrozone (10 microM), a mitochondrial metabolic inhibitor, produced a reduction in tension despite a slight increase in [Ca2+]i when applied to muscle precontracted by 90 mM [K+]o solution. These results indicate that eugenol relaxes the rabbit thoracic aorta while suppressing the Ca2+-sensitivity and both the uptake and extrusion mechanisms for Ca2+. To judge from the similarities between its actions and those of metabolic inhibitors, eugenol may produce its actions at least partly through metabolic inhibition.
Nishijima
H
H
Department of Health and Sports Science, Kawasaki University of Medical Welfare, Kurashiki, Japan.
Uchida
R
R
Kameyama
K
K
Kawakami
N
N
Ohkubo
T
T
Kitamura
K
K
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005054:Eugenol / Q000494:pharmacology*; D005453:Fluorescence; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009529:Nicardipine / Q000494:pharmacology; D010938:Plant Oils / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D014475:Uncoupling Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D010938:Plant Oils; D014475:Uncoupling Agents; D014665:Vasodilator Agents; D005054:Eugenol; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D009529:Nicardipine; D011188:Potassium; D002118:Calcium