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目的：观察质粒ＤＮＡ 对离体大鼠骨骼肌肌质网Ｃａ２＋ＡＴＰａｓｅ 活性及ｒｙａｎｏｄｉｎｅ 受体结合反应的影响。方法：参照Ｊｏｎｅｓ 等的方法比色测定肌质网Ｃａ２＋ＡＴＰａｓｅ 活性；以３Ｈｒｙａｎｏｄｉｎｅ 作为配基，液闪测定肌质网Ｃａ２＋ 释放通道ｒｙａｎｏｄｉｎｅ 受体与配体的结合。质粒ＤＮＡ 处理组预先将肌质网蛋白与质粒ＤＮＡ３７ ℃共同孵育３０ ｍｉｎ ，而后再测定肌质网Ｃａ２ ＋ＡＴＰａｓｅ 活性和ｒｙａｎｏｄｉｎｅ 结合反应。结果：预先用１０、２０ 和３０ μｇ ｐｃＤＮＡ３ 及ｐｃＤＮＡ３／ＡＮＦ处理后，肌质网Ｃａ２＋ＡＴＰａｓｅ 活性分别较对照组升高４５％ （Ｐ＜ ０．０５） ，６８ ％（ Ｐ＜ ０．０１） 和１０９ ％ （ Ｐ＜ ０．０１） 及１０９ ％ ，１１８％ 和１４５％ （Ｐ值均小于０ ．０１） ；质粒ｐｃＤＮＡ３ 可明显降低ｒｙａｎｏｄｉｎｅ 受体的亲和力，并使Ｂｍａｘ 增强。结论：质粒ＤＮＡ可能通过增强肌质网Ｃａ２ ＋ＡＴＰａｓｅ 的活性促进肌质网对Ｃａ２ ＋ 的摄入，通过影响ｒｙａｎｏｄｉｎｅ 受体而调控肌质网Ｃａ２ ＋ 释放。
Objective: To observe the effect of plasmid DNA on Ca2 + -ATPase activity and ryanodine receptor binding activity in skeletal muscle of isolated rat. Methods: The sarcoplasmic reticulum Ca2 + ATPase activity was determined by colorimetric assay according to the method of Jones et al. The binding of ryanodine receptor and ligand was determined by 3Hryanodine as ligand. In the plasmid DNA-treated group, the sarcoplasmic reticulum protein was incubated with the plasmid DNA at 37 ° C for 30 min, and then the sarcoplasmic reticulum Ca2 + -ATPase activity and the ryanodine binding reaction were measured. Results: Ca2 + -ATPase activity in sarcoplasmic reticulum was increased by 45% (P <0.05) and 68% (P <0.01), respectively, after treated with 10, 20 and 30 μg of pcDNA3 / And 109% (P <0.01) and 109%, 118% and 145%, respectively (all P values were less than 0.01). Plasmid pcDNA3 significantly reduced the affinity of ryanodine receptor and enhanced Bmax. CONCLUSION: Plasmid DNA may promote Ca2 + uptake in sarcoplasmic reticulum by enhancing the activity of Ca2 + -ATPase in sarcoplasmic reticulum, and regulate Ca2 + release from sarcoplasmic reticulum by affecting ryanodine receptor.