Abstract
Volvatoxin-A, the heat labile cardiotoxin present in the mushroom Volvariella volvacea, causes a competitive, dose and time-dependent inhibition of the Ca 2+-accumulating activity of a sarcoplasmic-reticulum rich microsomal fraction isolated from guinea pig ventricular muscle. The inhibition is accompanied by an activation of the Ca 2+-dependent ATPase enzyme. Concentrations of toxin which inhibit the Ca 2+-transporting activity of the microsomes render them leaky to Ca 2+, but do not effect the rate of incorporation of P 32. Ten μg/ml toxin failed to alter the activity of the Na + + K +-activated, ouabain sensitive ATPase enzyme. It damaged the fine morphology of the mitochondria, inhibited the ability of isolated mitochondria to accumulate Ca 2+, and had little effect on the ability of isolated plasma membranes to bind Ca 2+. These findings may explain why volvatoxin A increases the diastolic resting tension in heart muscle.
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.
