The effects of a sodium and a calcium channel blocker on lethality of mice injected with the yellow scorpion (Leiurus quinquestriatus) venom

ABSTRACT

Scorpion venom toxins generally produce similar effects by mainly acting on sodium channels, and to a lesser extent, on potassium, calcium, and chloride channels. This leads to increased release of neurotransmitters and mediators, resulting in a cascade of pathological events, involving the central nervous system, the autonomic nervous system, the cardiovascular and the respiratory system, eventually leading to death. The objective of this paper was to discover whether a sodium channel blocker, lidocaine, or a calcium channel blocker, verapamil, would prolong the survival of mice injected with the venom from the common yellow scorpion Leiurus quinquestriatus quinquestriatus (LQQ). For this purpose, mice were divided into 2 groups, each injected with a different venom dose (250 or 300 µg.kg-1, s.c.). Subgroups (n=10) from each group were given venom alone; different doses of lidocaine (4, 10, 15, or 20 mg.kg-1); or several doses of verapamil (0.01, 0.03, 0.1, 0.3, or 1 mg.kg-1). All doses of lidocaine and verapamil were intravenously administered 3 minutes before, 1, 5, and 15 minutes after venom injection. Percent surviving after 24 hours was recorded in addition to the time of death. In general, lidocaine significantly prolonged survival at the dose of 10 mg.kg-1 (P<0.05 and P<0.01, versus low and high dose of venom, respectively) or 15 mg.kg-1 (P<0.01 and P<0.001, versus low and high dose of venom, respectively; Covariance Wilcoxon survival statistics), especially when injected before the venom or in the early stages of envenomation. On the other hand, in all doses administered, verapamil was either toxic or showed non-significant results. Lidocaine, the sodium channel blocker, appears to play an important role in the protection from lethality of mice injected with LQQ venom, and significantly prolonged the survival time of mice whether injected before or in the early stages of envenomation.(AU)