[Effects of sevoflurane and enflurane on isometric tension and maximum velocity of shortening in glycerinated guinea pig masseter muscles].
To study the effects of inhalation anesthetics on the contractile system of masseter muscles, the Ca2+ concentration-isometric tension relationship and the maximum velocity of shortening were investigated in glycerinated guinea pig masseter muscles under the presence and absence of sevoflurane (10 mg% and 100 mg%) or enflurane (10 mg% and 100 mg%). Relative isometric tensions increased sigmoidally with an increase in Ca2+ concentration in all groups. K1/2 (pCa at the half maximum activated tension) was 6.53 in the control (absence of the anesthetics) and about 6.70 in the experimental groups under anesthetics regardless of the concentrations of anesthetics. The isometric tensions at higher Ca2+ concentrations were reduced by enflurane dose-dependently. They were also reduced by the low concentration of sevoflurane but increased by its high concentration. The maximum velocity of shortening was not influenced by these anesthetics (100 mg%) as far as the Ca2+ concentration was constant (pCa 6.36 or 5.94). These results suggest that in the masseter muscle, sevoflurane and enflurane alter the Ca2+ affinity in troponin C for actin filaments without changing the cross-bridge turnover rate.
Kaneko
K
K
Department of Dental Anesthesiology, Tsurumi University School of Dental Medicine, Yokohama.
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D004987:Ethers / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007530:Isoflurane / Q000494:pharmacology*; D008406:Masseter Muscle / Q000187:drug effects*; D008738:Methyl Ethers; D009119:Muscle Contraction / Q000187:drug effects*; D000077149:Sevoflurane
D000777:Anesthetics; D004987:Ethers; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane