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A bioassay for cobra cardiotoxin activity using semi-isolated cockroach heart
M J Klowden1, A J Vitale, M J Trumble
1Division of Entomology, University of Idaho, Moscow 83843.
Summary
Cobra cardiotoxin rapidly affects cockroach heart rate, retaining activity after boiling but losing it when heated with dithiothreitol. Cardiotoxin specifically binds to a 59,000 mol. wt membrane protein in cockroach hearts.
Area of Science:
- Toxicology
- Cardiovascular Physiology
- Molecular Biology
Background:
- Cobra cardiotoxins are known for their effects on cardiac function.
- Understanding the molecular mechanisms of cardiotoxin action is crucial for pharmacological research.
Purpose of the Study:
- To rapidly assess the biological activity of cobra cardiotoxin on heart rate.
- To investigate the stability of cardiotoxin activity under different conditions.
- To identify the specific binding target of cardiotoxin in cockroach heart tissue.
Main Methods:
- Utilized a semi-isolated cockroach heart preparation for real-time monitoring of heart rate.
- Established a dose-response curve for cardiotoxin activity.
- Investigated cardiotoxin stability through boiling and heating with dithiothreitol.
- Employed cross-linking of radiolabeled cardiotoxin to solubilized heart membranes.
Main Results:
- The cockroach heart preparation allowed for rapid determination of cardiotoxin activity.
- Cardiotoxin exhibited dose-dependent effects on heart rate.
- Cardiotoxin activity remained intact after boiling but was abolished by heating with dithiothreitol.
- Specific binding of cardiotoxin to a 59,000 mol. wt membrane protein was observed.
Conclusions:
- The semi-isolated cockroach heart is a viable model for studying cardiotoxin activity.
- Cardiotoxin's activity is sensitive to heat and reducing agents.
- A specific membrane protein of 59,000 mol. wt is a likely binding site for cardiotoxin in the cockroach heart.