H~＋－Ca^（2＋）交换在心肌细胞缺氧复氧过程中所致Ca^（2＋）超负荷的意

Action of H+一Ca2+ exchange in cultured heart cells after hypoxia and reoxygenation

多数研究资料表明：在心肌细胞发生氧反常和ｐＨ反常后，Ｈ￣＋一Ｎａ￣＋、Ｎａ￣＋一Ｃａ￣（２＋交换加强是细胞内Ｃａ￣（２＋）超载的重要机制。我们的研究表明，造成细胞Ｃａ￣（２＋）超载的原因，除Ｈ￣＋一Ｎａ￣＋、Ｎａ￣＋一Ｃａ￣（２＋）交换外，尚有Ｈ￣＋一Ｃａ￣（２＋）交换参加．本实验证实，在细胞缺氧１０、２０、３０和４０ｍｉｎ时，经Ｈ￣＋一Ｃａ￣（２＋）交换进入细胞的Ｃａ２＋量占同一时点细胞摄Ｃａ￣（２＋）总量的比率分别为（％）：１０．１±０．５、１２４±０．７、１１．８±０．４和１１．２±０．５、平均值为（％）：１１．４±０．９．当缺氧细胞再复氧后，这一比率显著增加。各时点的比率分别为（％）：２３．７±０．６、２２．３±０．５、２２．１±０．７和２０．５±０．８、平均值为（％）：２２．２±１２。这一结果表明：在ｐＨ反常所致Ｃａ￣（２＋）超载过程中，Ｈ￣＋一Ｃａ￣（２＋）交换的作用不容忽视。

Reoxygenation is more serious to hypoxic myocardial eells because it followedwith calcium o verload.It is already kno wn that the calcium overload is due toaugmentation of H+ 一Na+, Na+ 一Ca2+ exchanges during pH paradox. Our past experimentshowed that,besides H+ 一Na+,Na+ 一Ca+ exchanges,H+ 一Ca2+ exchange was also one ofthe reasons of calcium overload.The present experiment showed that H+ 一Ca2+ exchangecaused 11.4 per eent of total Ca2+uptake of myocardial cells after hypoxia, and the per- eentage was risen to 22.2 per cent after reoxygenation.It was suggested that duringintraeellular calcium overload the action of H+ 一Ca2+ exchange sho uld not be neglected.