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S- and P-type cobra venom cardiotoxins differ in their action on isolated rat heart

Alexey S. Averin1, Mikhail V. Goltyaev1, Tatyana V. Andreeva2, Vladislav G. Starkov2, Victor I. Tsetlin2, Yuri N. Utkin2 [ + show more ]

J Venom Anim Toxins Incl Trop Dis, 2022, 28:e20210110
Received: 19 October 2021 | Accepted: 15 December 2021 | Published online: 04 April 2022


Background: The cardiovascular system is one of the first systems to be affected by snake toxins; but not many toxins exert a direct effect on the heart. Cobra venom cardiotoxins are among those few toxins that attack the heart. Although the two cardiotoxin types (S and P) differ in their central-loop structure, it is not known whether they differ in their effect on the mammalian heart. We compared the effects of S- and P-type cardiotoxins, CTХ-1 and CTХ-2, respectively, from the cobra Naja oxiana, on the isolated rat heartMethods: An isolated rat heart perfused according to the Langendorff technique was used in this study to investigate the activity of cardiotoxins CTX-1 and CTX-2. The following parameters were registered: the left ventricular developed pressure, calculated as the difference between systolic and diastolic pressure in the left ventricle, the end-diastolic pressure, the heart rate, time to maximal end-diastolic pressure (heart contracture), and time to depression of the heart contraction. Results: Both cardiotoxins at the concentration of 5 μg/mL initially produce a slight increase in systolic intraventricular pressure, followed by its rapid decrease with a simultaneous increase in diastolic intraventricular pressure until reaching contracture. CTX-2 blocks cardiac contractions faster than CTX-1; in its presence the maximum diastolic pressure is reached faster and the magnitude of the developed contracture is higher. Conclusion: The P-type cardiotoxin CTX-2 more strongly impairs rat heart functional activity than the S-type cardiotoxin CTX-1, as expressed in its faster blockage of cardiac contractions as well as in more rapid development and greater magnitude of contracture in its presence.


Keywords: Cardiotoxin; Cobra venom; Contraction; Contracture; Myocardium; Perfused rat heart; Ventricular pressure.

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