Effects of sevoflurane on Ca2+ transsarcolemmal influx and Ca2+ release function of endoplasmic reticulum in isolated outer hair cells of guinea pigs / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of sevoflurane on ca2+ transsarcolemmal influx and ca2+ release function of endoplasmic reticulum in isolated outer hair cells (OHCs) of guinea pigs and the possible mechanism by which sevofhlrane acts on cochleas.Methods The experiment was performed in 2 parts.In experiment Itwelve adult guinea pigs(8 male,4 female)weighing 180-230 g were used.OHCs were mechanically sparated after enzymatic incubation.Thirty OHCs with favorable activity were divided into 3 groups (n=10 each)group I control(C);group Ⅱ low concentration sevoflurane (1.7%,group S1) and group Ⅲ high concentration sevoflurane(3.4%,group S2).The OHCs were stained with 6 umol/L Fluo-3AM in estefified form for 40 min.Group S1 and S2 were pretreated with 1.7% and 3.4% sevoflugsne respectively for 20 min.KCI 40 mmol/L was then added.The intracellular ionized Ca2+ concentration ([C2+]I) was determined byintracelhlar Ca2+ fluorescent intensity using laser scanning confocal microscope.The protocol of the experimentⅡ was the same as the experimentI.The only difference was that caffeine 20 mmol/L was added instead of KCI 40 mmol/L.Results In experiment Ithere was no significant difference in baseline[ca2+]I and[ca2+]I after being exposed to sevoflurane among the 3 groups.[Ca2+]I was significanfly increased after addition of KCI as compared with the baseline[Ca2+]I and was significantly lower in group Sl and S2 than in group C and was the lowest in group S2.In experimentⅡthe[ca2+]I was significantly increased after addition of caffeine but there was no significant difference in[Ca2+]I among the 3 groups.Conclusion Sevoflurane can inhibit voltage-dependent Ca2+ channel opening in a concentration-dependent manner but can not affect ryanodine-sensitive Ca2+ release function of endoplasmic reticuhm in isolated outer hair cells of guinea pigs.