[Effect of cholinesterase (ChE) reactivators on hemodynamics in animals. I. Reactions of the circulatory and respiratory systems of rabbits after administration of ChE reactivators].

Studies on the dynamics of changes in the circulatory and respiratory system in rabbits were carried out after intravenous injection of ChE reactivators used in treatment of poisoning with phosphoorganic compounds (FO). Blood flow in the carotid artery, arterial pressure, frequency and amplitude of breathing were measured. From the above data pulse rate and coefficient of vesself resistance were calculated. The results obtained indicate that the reactions in the circulatory and respiratory system depend on the kind of the reactivator, the size of its dose and time of action. Pralidoxim--PAM (at a dose of 10, 20, 40 mg/kg) acts cholinergically on the muscular coat o blood vessels, causing their shrinkage, which is proved by decreased blood flow with simultaneous increase of vessel resistance. The increase of vessel resistance was directly proportional to the dose of pralidoxim and often caused an increase in arterial pressure. Pralidoxim did not show a larger effect on the function of the heart. The action of obidoxim--Toxogonin or Toxobidin--does not only depend on the size of the dose but on the time of action as well. At small doses (10 mg/kg), obidoxim increases blood flow after 15 min, then causes shrinkage of blood vessels and decreases blood flow with increased vessel resistance. At larger doses (20, 40 mg/kg) a constant increase of blood flow is maintained, despite frequently decreased arterial pressure with simultaneously decreased vessel resistance. This accounts for blood vessel dilatation. The reactivators studied stimulate the function of the respiratory system by increased frequency of breathing, but its amplitude was effected to a lesser extent. It was also shown that ChE activity in blood was not changed significantly. The action of the indoxims studied was similar to that of Toxobidin (Polfa) and Toxogonin (E. Merck).