Evidence for a direct action of Tityus serrulatus scorpion venom on the cardiac muscle

A. L. Teixeira, B. F. Fontoura, L. Freire-Maia, C. R.S. Machado, E. R.S. Camargos, M. M. Teixeira

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


The ability of toxins to activate the cardiovascular system plays an important role in the morbidity and lethality of the Tityus serrulatus scorpion envenoming. Most of the actions of the scorpion toxins are indirect and due to the release of adrenergic and cholinergic neurotransmitters. Accordingly, treatment following envenoming is targeted towards inhibition of adrenergic and cholinergic receptors. Here, we have sought evidence for a direct action of T. serrulatus venom on the isolated rat heart (Langendorff's method). We show that the bradycardia induced by T. serrulatus venom was completely blocked by atropine, a muscarinic receptor antagonist. Similarly, the increase in heart rate that follows the venom-induced bradycardia was totally inhibited by a β1-adrenoceptor antagonist or by chemical sympathetic denervation with 6-hydroxydopamine. In contrast to these findings, the venom-induced increase in contractile force was not modified by β1-adrenoceptor blockade or by chemical sympathetic denervation. The results clearly demonstrate that the chronotropic effects of T. serrulatus are dependent on neurotransmitter release, but the inotropic effects are not. The neurotransmitter-independent increase in contractility seems to be a direct action of the venom on cardiomyocytes. We suggest that this direct effect on cardiac fibers may play a role in the development of cardiac arrhythmias and contractility defects following envenoming with T. serrulatus scorpion. Copyright (C) 2000 Elsevier Science Ltd.

Original languageEnglish (US)
Pages (from-to)703-709
Number of pages7
Issue number5
StatePublished - 2001
Externally publishedYes


  • Heart
  • Scorpion venom
  • Tityus serrulatus

ASJC Scopus subject areas

  • Toxicology


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