Effects of eugenol, an essential oil, on the mechanical and electrical activities of cardiac muscle.
Eugenol (EUG) acts as a calcium antagonist but effects on the contractile proteins could also occur. We investigated inotropic effects of EUG in rat left ventricular papillary muscles, measuring isometric force, time variables, and post rest potentiation and EUG actions on the effects of Ca2+ (0.62 to 2.5 mM) and isoproterenol (5 ng/ml), on myosin ATPase activity and on the calcium currents in single ventricular myocytes. EUG reduced tension and time variables without altering the sarcoplasmic reticulum activity increasing post-pause relative potentiation. Isoproterenol and Ca2+ counteract these negative inotropic effects. Tetanic tension diminished, but not the myosin ATPase activity suggesting an isolated sarcolemmal effect. EUG 0.1 mM decreased the Ca2+ current amplitude in the entire potential range tested and 0.5 mM almost completely blocked this inward current. Results suggested that EUG depresses force without affecting the contractile machinery and its action is the only dependent blockade of the calcium inward current.
Damiani
Carlos Estevan Nolf
CE
Department of Physiological Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil.
Moreira
Cleci Menezes
CM
Zhang
Heng Tao
HT
Creazzo
Tony Louis
TL
Vassallo
Dalton Valentim
DV
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology; D002316:Cardiotonic Agents / Q000494:pharmacology; D002469:Cell Separation; D003285:Contractile Proteins / Q000187:drug effects; D004594:Electrophysiology; D005054:Eugenol / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000201:enzymology; D009218:Myosins / Q000378:metabolism; D009822:Oils, Volatile / Q000494:pharmacology*; D010210:Papillary Muscles / Q000187:drug effects; D018408:Patch-Clamp Techniques; D051381:Rats
D002121:Calcium Channel Blockers; D002316:Cardiotonic Agents; D003285:Contractile Proteins; D009822:Oils, Volatile; D005054:Eugenol; D009218:Myosins; D007545:Isoproterenol; D002122:Calcium Chloride