Acute poisoning with Anthio is associated with a gradual drop of blood pressure in the greater circulation and the development of intensive metabolic acidosis, despite normoxia still observed in the arterial blood and a somewhat increased oxygen capacity of the blood, this indicating mitochondrial injury and disordered tissue respiration.

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It is shown that general anesthesia strongly influences the resistance of animals to poisoning with organophosphorus compounds (OPC) such as Anthio, weakens compensatory/adaptive responses, and possibly acts synergistically with OPC in impairing tissue respiration. One to three days after peroral administration of Anthio, reduced oxygen tension in arterial blood and increased heart and respiratory rates were recorded in cats, although the arterial blood pressure tended to drop markedly. Anthio poisoning led to profound changes in the autonomic regulation of functions, which was manifested in sharply decreased parasympathetic influences. The function of the brain's GABA-ergic system did not change appreciably. Key Words: cats; anesthesia; organophosphorus compounds; acute poisoning; Anthio pesticideWe found previously that almost all cats die 2-3 h after their acute experimental poisoning in the pentobarbital-anesthetized state with the organophosphorus pesticide Anthio given per os in a dose equal to 20% of its LDs0 value [15]. Such an effect of Anthio is not consistent with what is known about the systemic toxicity displayed by it at this dose level and raises the question of the role pentobarbital anesthesia might play in aggravating the adverse effects of acute experimental poisoning.The present study was designed to examine the impact of pentobarbital anesthesia on major parameters of respiration and systemic circulation several days after peroral administration of Anthio to alert cats in the dose indicated above. In such cats we also evaluated the effect of atropine, which is usually employed in cases of poisoning with cholinestInstitute of General Pathology and Pathological Physiology, Russian Academy of Medical Sciences, Moscow. {Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences) erase blockers, as well as the effect from the activation of the GABA-ergic system, which is closely associated with the cholinergic system [12]. MATERIALS AND METHODSThe experiments were conducted on 7 random-bred adult cats of both sexes weighing 2.2-2.8 kg. Under mild ether anesthesia, the animals were administered intragastrically, via a catheter, the organophosphorus pesticide Anthio (Formothion, Sandoz) in the form of an emulsion in a dose of 1/5 of the LDs0, after which the ether supply was discontinued. Several days later, the cats were anesthetized with sodium pentobarbital (40 mg/kg intraperitoneally) and prepared for examination. Details of this preparation and of the procedures used to measure parameters of respiration, systemic hemodynamics, and arterial blood are described in our previous article [15]. Five cats were injected intravenously with atropine (0.5 mg/kg) and with

Experiments with cats using ultrasound show that exposure to the organophosphorus compound Anthio leads to a reduction of vascular resistance of the carotid and internal maxillary arteries. The bloodflow in these arteries does not decrease for a long time. The share of bloodflow in the internal maxillary artery is increased vis-a-vis the total flow in the carotid artery. A reduction of the blood supply to the brain is observed only by the end of the experiment with a blood pressure of 40 to 50 mm Hg.

Experiments on cats demonstrate the capacity of alert animals to compensate for disorders in pulmonary and systemic hemodynamics caused by organophosphorus compounds. Heart rate, systemic arterial pressure, and total peripheral resistance completely normalize on day 3 after exposure. Pulmonary vascular resistance and pulmonary blood pressure remain negligibly increased.