心肌肥大时细胞核被膜核苷三磷酸酶活性及mRNA出核转运的变化

目的：探讨心肌肥大时心肌细胞ｍ ＲＮＡ 出核转运率及核被膜核苷三磷酸酶（ ＮＴＰａｓｅ） 活性的变化。方法：采用腹主动脉缩窄法复制大鼠心肌肥大模型，密度梯度离心法制备心肌细胞核被膜，观察心肌肥大时对心肌ＮＴＰａｓｅ 活性和成熟ｍ ＲＮＡ 出核转运速率的影响。结果：早、晚期肥大组心肌细胞核被膜ＮＴＰａｓｅ 最大反应速率以ＡＴＰ 为底物时较对照组增加２５ ％ ～６２ ％ （ Ｐ＜ ０ ．０１） ，以ＧＴＰ 为底物时增加８ ％ ～４４ ％ （ Ｐ＜ ０ ．０１） ，其中晚期肥大组ＮＴＰａｓｅ 最大反应速率增加幅度低于早期组。早期肥大组细胞核被膜ＮＴＰａｓｅ Ｋｍ 值不变，晚期组ＮＴＰａｓｅ Ｋｍ 值下降，以ＡＴＰ 和ＧＴＰ 为底物时晚期肥大组Ｋｍ 值分别下降２２ ％ 和８６ ％ 。早期肥大组１０ ｍｉｎ 心肌细胞核ｍ ＲＮＡ 出核转运率以ＡＴＰ 或ＧＴＰ 启动反应时分别较对照组增加６８ ％ （ Ｐ＜ ０－０１） 或７８ ％ （ Ｐ＜ ０ ．０１） ，晚期肥大组增加幅度不如早期组大，仅增加２７ ％ 和２１－７ ％ （ Ｐ＜ ０－０１） 。结论：大鼠心肌肥大组细胞核被膜ｍ ＲＮＡ 出核转运率的增加可能是心肌肥大时蛋白质合成增加的一个重要原因，而这种ｍＲＮＡ 出核转运率的增加可能与

Alteration of cardiomyocyte nuclear enveloped associated NTPase activities and mRNA transport in rat hypertrophy

AIM and METHODS: To oberserve the possible alterations of mRNA nucleocytoplasmic transport and nuclear envelope associated NTPase activity during rat heart hypertrophy(Hyper), cardiomyocyte nuclear envelope portions were prepared by density gradient centrifugation methods from heart hypertrophic rat model and were further detected for their mRNA transport rates and NTPase activities. RESULTS: The hypertrophic cardiomyocyte NTPase Vmax values at 1 week group(early hyper) and 4 week group(late hyper) were all increased significantly in both of ATP and GTP as substrates with much higher argumental extent in early hyper group; their K m values were kept constant in early hyper group and were decreased only in late hyper groups. The 10 min mRNA transport amounts in early hyper as well as late hyper groups in both ATP and GTP initial activators was correspondingly enhanced significantly also. CONCLUSION: The increased mRNA transport during rat heart hypertrophy might be one of the important reasons of their increase in protein synthesis, attributing to the nuclear envelope associated NTPase activities contributions.