Abstract
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 μM) decreased by 27% (human muscle), or had no effect on (equine muscle), the threshold of Ca2+-induced Ca2+ release. If terminal cisternae fractions were first preloaded with Ca2+ to greater than 65% of the threshold of Ca2+-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 Ca2+-induced Ca2+ release did not elicit Ca2+ release in preparations from either species. Ruthenium red (10 μM) antagonized CTX-induced Ca2+ release, whereas dantrolene (10 μM) 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 Ca2+-modulated Ca2+ release process and in understanding regulation of Ca2+ release in skeletal muscle from different species.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
