Regional Blood Flow after Intravenous Administration of Scorpion Venom in Rats

The accidents by scorpion stings in Brazil, particularly in Belo Horizonte, capital of Minas Gerais state are caused by Tityus serrulatus species and accounts for fatal stings, especially in children and elderly people. The death in severe evenomation is caused by a circulatory shock, associated with respiratory and cardiovascular arrhythmias, cardiogenic shock, pulmonary edema, respiratory depression, acid-base disorders and serious coagulation disturbance. Our group has been involved in the study of several aspects of the mechanism of action of scorpion toxins injected in animals. However some aspects of the envenomation, such as, the regional blood flow distribution to several organs need further studies. The aim of the present work was to determine the flow to different organs after intravenous injection of the gamma fraction of toxins isolated from the T. serrulatus scorpion venom adding more information that would contribute to a better understanding of the pathophysiology of scorpion sting envenomation. The fluorescent microspheres deposition technique was used to evaluate the regional blood flow and regional vascular resistance of several organs in anesthetized rats after Tityus serrulatus scorpion venom (Tx) injection. Fluorescent microspheres of different colors were injected into the left ventricle through the carotid artery. Reference blood samples were collected from the left femoral artery at baseline (before) and 5, 15 and 30 min after toxin injection. Tissue samples from the adrenal gland, spleen, brain, heart, liver, ileum, mesentery, muscle, skin, lung and kidney were harvested and prepared for fluorescent measurements using a spectrophotometer. Hemodynamic parameters were monitored continuously. Blood flow variation was detected in the tissue samples and were different among the organs. The most common finding was a decrease in flow, varying with time and the severity of the intoxication. However, intrinsic mechanisms of auto-regulation of blood flow and vascular resistance possibly protect the heart and the brain from hypoperfusion after Tx injection.