Intracellular Mechanism of Sevoflurane`s Effect on Isolated Vascular Rings of the Rabbits

Kim, Won Oak; Min, Kyeong Tae; Kil, Hae Keum; Jung, Jai Won; Kim, Jong Rae

Abstract

The purpose of this study were to elucidate how sevoflurane affects vascular smooth musde and to understand the intracellular mechanism of sevoflurane. Isolated aortic rings of the rabbit were examined. Rings were mounted on tissue bath containing 40 ml of modified Krebs solution bubbled with 95% O2/5% CO2 and attached to force transducers. The preparations were contracted with either 40 mM KC1, or 0.1 uM norepinephrine followed by 0.1 uM acetylcholine (and 1 nM ryanodine)- or 2.8 mM lidocaine induced relaxation. At steady state contraction or relaxation, the effects of sevoflurane (2, 4, 5%) were studied. The steady state tension before administration of sevoflurane was considered as 100% and the changing tension during sevoflurane was expressed as a percentage. Sevoflurane (2, 4, 5%) produced relaxing effects (99.4+/-0.6, 98.1+/-0.9, 95.9+/-1.0%) on KC1-induced tension, independent of endothelium. Sevoflurane increased tension in the acetylcholine (55.4+/-5.1%)- or lidocaine (75.3+/-8.3%)- relaxed state (acetylcholine: 73.6+/-5.3, 86.8+/-3.2, 94.1+/-5.2%, acetylcholine+ryanodine ; 63.7+/-4.6, 68.6+/-7.2, 70.4+/-2.5%, lidocaine ; 83.7+/-7.0, 84.6+/-12.1, 85.3+/-4.4%). The effects were dose-dependent manner. It is concluded that sevoflurane directly alters vascular contraction or relaxation in relation to Ca2+ mobilization on condition and that mechanism of sevofluranes effects on the sarcoplasmic reticulum may play a primary role.