Study for the action and side effects of anesthetics using plasma membrane Ca-ATPase as a model

近年来有研究报道苯二氮卓类药物对Na^+，K^+-ATP酶活性有抑制作用，但具体情况尚不清楚。本研究旨在阐明苯二氮卓类药物对Na^+，K^+-ATP酶的抑制机制。用纯化的兔脑Na^+，K^+-ATP酶测定了苯二氮卓类药物（咪达唑仑、地西泮和氟硝西泮）对Na ^+，K^+-ATP酶和Na^+-ATP酶活性及Na^+，K^+-ATP酶磷酸化中间产物（EP）的影响。获得了以下结果。三种苯二氮卓类药物均以剂量依赖性方式抑制Na^+，K^+-ATP酶和Na^+ -ATP酶活性以及EP的形成，地西泮、咪达唑仑和氟硝西泮对Na^+，K^+-ATP酶活性的半数最大抑制浓度（Ki 0.5）分别为0.6、0.42和0.25 mM。Ki 0.5值的大小顺序为EP形成> Na^+，K^+-ATP酶活性> Na^+-ATP酶活性，提示苯二氮卓类药物对Na^+，K^+-ATP酶的抑制作用主要是通过抑制EP形成和Na^+，K^+-ATP酶活性来实现的。 ...更多信息 在EP形成后的序列上。通过稀释其浓度，所有苯二氮卓类药物的活性均部分恢复。氟马西尼不影响苯二氮卓类药物对Na^+，K^+-ATP酶活性和EP形成的抑制作用及抑制恢复试验，表明氟马西尼不与苯二氮卓类药物竞争Na ^+，K ^+-ATP酶的反应，苯二氮卓类药物与GABA_A受体的结合位点结构不同。在其他实验中，我们发现局麻药利多卡因、普鲁卡因和地布卡因通过抑制EP的形成来抑制Na^+，K^+-ATP酶活性，局麻药的某些方面可能与抑制Na^+，K^+-ATP酶活性有关。我们还发现，不同种类的麻醉药对Na^+，K^+-ATP酶活性的抑制机制是不同的，异氟烷通过降低EP对钾离子的敏感性来抑制该活性。少

Recently it was reported that the activity of Na^+,K^+-ATPase was inhibited by benzodiazepines, but detail was not yet clear. We aimed to clarify the inhibition mechanism of benzodiazepines for Na^+,K^+-ATPase. The effects of benzodiazepines (midazolam, diazepam and flunitrazepam), on Na^+,K^+-ATPase and Na^+-ATPase activities, and phosphointemiediate (EP) of Na^+,K^+-ATPase were tested using Na^+,K^+-ATPase purified from rabbit brain. The following results were obtained. All three benzodiazepines inhibited Na^+,K^+-ATPase and Na^+ -ATPase activities, and EP formation in a dose-dependent manner and the half maximal inhibition concentrations (Ki 0.5) for Na^+,K^+ATPase activity were 0.6, 0.42 and 0.25 mM, for diazepam, midazolam and flunitrazepam, respectively. Tlie orders of Ki 0.5 values were EP formation > Na^+,K^+-ATPase activity > Na^+-ATPase activity for all benzodiazepines, suggesting that inhibition of Na^+,K^+-ATPase by benzodiazepines was mainly caused by inhibiting the reacti … More on sequence after EP formation. The activities were partially recovered for all benzodiazepines by dilution of their concentrations. Flumazenil did not affect the inhibition of Na^+,K^+-ATPase activity and EP formation by benzodiazepines, and recovery test of inhibition, suggesting that flumazenil did not compete with the reactions of benzodiazepines on Na^+,K^+-ATPase and mat the.structure of binding sites of Na^+,K^+-ATPase for benzodiazepines are different from those of GABA_A receptor. In other experiments, we showed that local anesthetics, lidocaine, procaine and dibucaine, inhibited Na^+,K^+-ATPase activity by inhibition of EP formation and some aspects of local anesthesia may relate to the inhibition of Na^+,K^+-ATPase activity. We also showed that the inhibitory mechanisms of general anesthetics against Na^+,K^+-ATPase activity are diverse among the different categories of anesthetics and that isoflurane inhibit the activity by decrease in the sensitivity of EP to potassium ions. Less