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Frequency-dependent neuromuscular blockade by textilotoxin in vivo.
D R Lloyd1, G M Nicholson, I Spence
1Department of Pharmacology, University of Sydney, NSW, Australia.
Summary
Neuromuscular blockade from textilotoxin and beta-bungarotoxin correlated with respiratory failure in mice at stimulation rates of 0.5 Hz and higher. Heart rate increased with textilotoxin before death.
Area of Science:
- Neuroscience
- Pharmacology
- Toxicology
Background:
- Neuromuscular blockade is a critical effect of certain toxins.
- Understanding the kinetics of toxin-induced blockade is essential for predicting outcomes.
Purpose of the Study:
- To investigate the effect of stimulation frequency on neuromuscular blockade induced by textilotoxin and beta-bungarotoxin.
- To correlate the onset of neuromuscular blockade with respiratory failure and other physiological changes.
Main Methods:
- Administration of textilotoxin or beta-bungarotoxin to anaesthetized mice.
- Electrophysiological monitoring of neuromuscular blockade in hindlimb interdigital muscles.
- Varying stimulation frequencies (0.5 Hz and above) to assess blockade timecourse.
Main Results:
- Neuromuscular blockade onset coincided with respiratory failure at stimulation rates of 0.5 Hz and above for both toxins.
- Textilotoxin administration (50 micrograms/kg) led to an increased heart rate prior to death.
- No significant changes were observed in the electrocardiogram shape with textilotoxin.
Conclusions:
- Stimulation frequency significantly influences the manifestation of neuromuscular blockade by these toxins.
- The findings provide insights into the physiological impact and progression of textilotoxin and beta-bungarotoxin toxicity.