Shetty S S, Frank G B
J Pharmacol Exp Ther. 1985 Jul;234(1):233-8.
Three opioids, viz. methadone, morphine and meperidine, were tested separately for their effects on the rate of 45Ca++ efflux from frog toe muscles. The experimental procedures were designed to provide reliable measurements of the displacement of 45Ca++ from surface binding sites using the thin and light toe muscle. La (2 mM) was used to test the ability of the experimental procedure to detect the displacement of calcium bound superficially to the muscle fiber membrane. La not only enhances the rate of efflux of 45Ca++ from surface membrane superficial stores but also inhibits the efflux of intracellular calcium. Of the opioids tested, only methadone (10(-4) or 10(-3) M) caused a slight but significant increase in the rate of 45Ca++ efflux from the surface bound (i.e., the La -displaceable) store of calcium of the muscle. The "calcium-displacement" effect of methadone was much weaker than that seen with La . Morphine (10(-4) or 10(-3) M) or meperidine (10(-4) or 10(-3) M) did not show any such effect on the bound 45Ca++ desaturation rate even under experimental conditions modified to enable the detection of the displacement of even small amounts of 45Ca++ from superficial binding sites on the muscles.
分别测试了三种阿片类药物，即美沙酮、吗啡和哌替啶对蛙趾肌45Ca++流出率的影响。实验程序旨在利用薄而轻的趾肌，对45Ca++从表面结合位点的位移进行可靠测量。使用镧（2 mM）来测试实验程序检测与肌纤维膜表面结合的钙的位移的能力。镧不仅能提高45Ca++从表面膜浅表储存库的流出率，还能抑制细胞内钙的流出。在所测试的阿片类药物中，只有美沙酮（10^(-4)或10^(-3) M）会使肌肉表面结合（即镧可置换）的钙储存库的45Ca++流出率略有但显著增加。美沙酮的“钙置换”作用比镧的作用弱得多。吗啡（10^(-4)或10^(-3) M）或哌替啶（10^(-4)或10^(-3) M）即使在经过改进以能够检测肌肉表面结合位点上极少量45Ca++位移的实验条件下，对结合的45Ca++去饱和率也未显示出任何此类作用。
