Hornet venom is a mixture of various substances, each acting in a different manner. Some of these substances are volatile compounds and of low molecular weight (ketones), biogenic amines (histamine, acetylcholine, dopamine, serotonin, and other catcholamines) and polypeptides (mainly kinins). Other substances within the venom are of high molecular weight (mainly enzymes and toxic proteins).
The quantity of venom introduced by a single sting into a victim (man or animal) is too small to result in a systemic effect. Therefore the damage incurred is strictly localized or of an allergic nature (in cases of repeated stings in a sensitized human). In the latter instances, the injection of the venom leads to a type 1 hypersensitivity response, such as that mediated primarily by the IgE immunoglobins bound to mast cells and basophils. A large number of stings or, alternatively, the experimental injection of a greater quantity of hornet venom provokes a systematic effect, affecting also the cardiovascular system.
The effect of hornet venom sac extract on the functioning of the cardiovascular system was assessed in dogs by concomitant examination of the following parameters: systemic blood pressure, blood pressure and dp/dt derivative of the left ventricle of the heart, heart rate, direct measurements of the cardiac output and body temperature.
The effect of adult hornet venom sac was rapid and led to a sharp drop in the systemic blood pressure, a similar drop in the pressure and dp/dt derivative in the left ventricle, to bradycardi, immediate thickening of the left ventricular wall and to an immediate rise in the cardiac output. The canine temperature dropped immediately following the administration of venom sac extract and remained at the new level for at least 30 minutes
