PERIPHERAL EFFECTS OF TITYUS-SERRULATUS SCORPION-VENOM

In this review we describe the peripheral effects induced by Tityus serrulatus scorpion venom and two of the most important toxins- tityustoxin and toxin Ts-gamma purified from the crude venom. The complex cardiac arrhythmias elicited by the venom or the toxins were explained by the release of catecholamines and acetylcholine. In isolated rat atria, toxin Ts-gamma induced mainly cholinergic effects of long duration. Arterial hypertension was mostly due to release of catecholamines from postganglionic nerve endings and adrenal glands with subsequent stimulation of alpha-adrenergic receptors. The pulmonary edema was related to an adrenergic discharge with stimulation of alpha-adrenergic receptors, leading to an increase of preload and afterload and subsequent heart failure (cardiogenic factor) and also release of permeability factors in lungs, such as the platelet-activating factor (non-cardiogenic factor). The complex respiratory arrhythmias elicited by scorpion toxins in rats were mainly due to stimulation of afferent visceral receptors, being therefore reflex in nature. The scorpion toxin (tityustoxin) also induced pre- and postsynaptic actions at the neuromuscular junctions. The purified scorpion toxins evoked, in anesthetized rats, the appearance of acute gastric injuries in the glandular mucosa (ulcers), simultaneously with an increase in volume, acidity and pepsin output of the rat stomach, explained mostly by the release of acetylcholine and histamine.