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Cardiovascular effects of Buthus martensii (Karsch) scorpion venom
R Wang1, P Moreau, A Deschamps
1Département de Physiologie, Faculté de Médecine, Université de Montréal, Québec, Canada.
Insights
Buthus martensii (Karsch) scorpion venom significantly raises blood pressure and enhances cardiac and arterial contractions in rats. These cardiovascular effects appear mediated by altered InsP3 metabolism in cardiac cells, not intracellular calcium in vascular cells.
Area of Science:
- Pharmacology
- Toxicology
- Cardiovascular Research
Background:
- Buthus martensii (Karsch) (BMK) scorpion envenomation is a prevalent health issue in China.
- BMK scorpion venom is utilized in traditional Chinese medicine.
- Systematic investigation into the cardiovascular effects of BMK venom is lacking.
Purpose of the Study:
- To systematically investigate the cardiovascular effects of Buthus martensii (Karsch) scorpion venom.
- To elucidate the mechanisms underlying the venom's cardiovascular actions.
Main Methods:
- Intravenous injection of BMK venom in conscious rats to assess blood pressure and heart rate.
- In vitro studies using isolated atrial and arterial strips to evaluate contractile responses.
- Analysis of intracellular calcium ([Ca2+]i) in cultured vascular cells and InsP3 metabolism in cardiac myocytes.
Main Results:
- BMK venom caused a dose-dependent increase in blood pressure in rats, sustained for over 50 minutes.
- Heart rate remained unchanged in conscious rats.
- In vitro, BMK venom increased the force of contraction in atrial and arterial strips.
- These effects were inhibited by alpha 1-adrenergic antagonists (prazosin and tolazoline).
- BMK venom did not alter [Ca2+]i in vascular and endothelial cells but increased InsP3 metabolism in cardiac myocytes.
Conclusions:
- BMK venom exerts significant cardiovascular effects, including hypertension and enhanced cardiac and vascular contractility.
- The cardiovascular effects are likely mediated by an alteration in InsP3 metabolism within cardiac myocytes.
- The mechanism does not involve changes in intracellular calcium concentrations in vascular smooth muscle and endothelial cells.
Abstract:
Buthus martensii (Karsch) (BMK) scorpion envenomation is a common medical problem in China and BMK scorpion has been widely used in traditional Chinese medicine. However, the cardiovascular effects of this venom have not been systematically investigated. In the present study, i.v. BMK venom injection significantly increased the blood pressure in conscious rats in a concentration-dependent manner (ED50 = 59 +/- 12 micrograms/kg). The increase in blood pressure occurred within 1 min of injection of the venom and was sustained for more than 50 min. Heart rate was not changed by the venom in conscious rats. In vitro studies with BMK venom revealed the increase in the force of contraction, without modification of the contraction frequency (within 20 min) of isolated atrial strips. Contractions of isolated arterial strips from aorta, renal and vertebral arteries were also enhanced by BMK venom with a time lag of 8 min between the application of the venom and the initiation of the contraction. Furthermore, BMK venom-induced rises in blood pressure in vivo and increased contraction of isolated vessel strips were inhibited by prazosin and tolazoline, respectively, two alpha 1-adrenergic antagonists. BMK venom alone did not alter intracellular calcium concentrations, [Ca2+]i, in cultured vascular smooth muscle cells and endothelial cells. However, BMK venom significantly increased the metabolism of InsP3 in dispersed cardiac myocytes, indicating a direct effect on cardiac myocytes. These results demonstrate the significant cardiovascular effects of BMK venom, which may be mediated by an alteration in InsP3 in cardiac myocytes but not by [Ca2+]i in vascular smooth muscle cells.