Fletcher J E, Tripolitis L, Beech J
Department of Anesthesiology, Hahnemann University, Philadelphia, PA 19102-1192.
Toxicon. 1993 Jan;31(1):43-51. doi: 10.1016/0041-0101(93)90355-m.
The modulation of Ca2+ release by a cardiotoxin (CTX) from Naja naja kaouthia snake venom was examined in terminal cisternae-containing fractions from equine and human skeletal muscle. Pretreatment with CTX (10 microM) decreased by 27% (human muscle), or had no effect on (equine muscle), the threshold of Ca(2+)-induced Ca2+ release. If terminal cisternae fractions were first preloaded with Ca2+ to greater than 65% of the threshold of Ca(2+)-induced Ca2+ release and then CTX added, an immediate and sustained release of Ca2+ occurred in preparations from both species. Addition of CTX after a Ca2+ preload of less than 60% of the threshold of Ca(2+)-induced Ca2+ release did not elicit Ca2+ release in preparations from either species. Ruthenium red (10 microM) antagonized CTX-induced Ca2+ release, whereas dantrolene (10 microM) did not. These findings suggest that the effects of CTX on the Ca2+ release channel are dependent on Ca2+ preload and that CTX may be an important probe of the Ca(2+)-modulated Ca2+ release process and in understanding regulation of Ca2+ release in skeletal muscle from different species.
在马和人的骨骼肌含有终末池的组分中，研究了眼镜王蛇蛇毒的一种心脏毒素（CTX）对Ca2+释放的调节作用。用CTX（10 microM）预处理使（人肌肉中）Ca2+诱导的Ca2+释放阈值降低了27%，或者（马肌肉中）没有影响。如果终末池组分首先用Ca2+预加载至大于Ca2+诱导的Ca2+释放阈值的65%，然后加入CTX，则在两个物种的制备物中都会立即发生Ca2+的持续释放。在Ca2+预加载至小于Ca2+诱导的Ca2+释放阈值的60%后加入CTX，在两个物种的制备物中均未引发Ca2+释放。钌红（10 microM）拮抗CTX诱导的Ca2+释放，而丹曲林（10 microM）则无此作用。这些发现表明，CTX对Ca2+释放通道的作用取决于Ca2+预加载，并且CTX可能是Ca2+调节的Ca2+释放过程的重要探针，有助于理解不同物种骨骼肌中Ca2+释放的调节。
