Background
Hemodynamic manifestations are the leading causes of death after scorpion sting. This study was performed to evaluate the dose-dependent effect of dobutamine on hemodynamic perturbations induced by Buthus occitanus tunetanus (Bot) scorpion venom in rats.
Material and Method
Bot venom (850 microg/kg) was administered intravenously. Five minutes later the animals were perfused with vehicle or dobutamine (5, 10, and 20 microg/kg/min). The effects of Bot and dobutamine treatment on systolic arterial pressure (SAP), diastolic arterial pressure (DAP), heart rate (HR), and survival of the rats were examined.
Results
Bot venom caused a biphasic variation of SAP and DAP. These parameters reached their maximum values immediately after venom administration, followed by a substantial progressive fall. There was a remarkable decrease in HR, which never returned to its initial value. Dobutamine treatment proved to have significant effects on hemodynamic perturbations only in the group treated at the rate of 20 microg/kg/min. In these animals, the decreases in SAP, DAP, and HR were markedly less important after the 10th min after envenomation (P<0.05 vs. control). Survival rates between the groups showed a statistically significant difference (P<0.01). The rats receiving 20 microg/kg/min dobutamine showed the highest survival rate (P<0.05 vs. control).
Conclusions
Our results indicate that Bot venom (850 microg/kg) causes severe hemodynamic perturbations which were reversed only by high doses of dobutamine (20 microg/kg/min), demonstrating the necessity of adapting the dobutamine dose to the degree of envenomation gravity for optimizing its effect.

Keywords: Systole - drug effects, Scorpion Venoms - toxicity, Dose-Response Relationship, Drug, Hemodynamics - drug effects, Dobutamine - pharmacology, Blood Pressure - drug effects