Evaluation of antihypoxic effects of therapeutic breathing mixtures with high argon content on the example of acute blood loss in laboratory animals: a preclinical randomized experimental study

Abstract

Background. According to the hypothesis of the study, the therapeutic efficacy of measures to treat hypoxic (ischemic) emergencies can be significantly increased by using an artificial gas mixture with normal or increased oxygen content and a high content of argon, being bioactive despite its chemical inertness.Objective. To experimentally evaluate the antihypoxic effects of argon on the example of acute massive blood loss in experimental animals.Methods. The study was carried out on 72 albino male gray rats with a baseline body weight of 220–250 g. The experiments were performed at the premises of the Konstantinov St. Petersburg Nuclear Physics Institute of the Kurchatov Institute and the Smorodintsev Research Institute of Influenza (Russia). Prior to the experiment, the animals were quarantined for 2 weeks in the vivariums of the performing organizations. Acute massive blood loss in rats was formed by taking blood (12 ± 1% of body weight on average) using syringe method by transcutaneous cardiac puncture. Rats were randomized into 3 groups (24 individuals each) depending on the gaseous medium where the animal was placed after artificial blood loss. Composition of the applied gaseous medium in the comparison groups: medium No. 1 — oxygen 21% vol.; argon — 30% vol.; nitrogen — the rest; medium No. 2 — oxygen 21% vol.; argon — the rest; medium No. 3 (control) — air. The postoperative follow-up (post-conditioning) for 8 hours involved assessing and recording the following indicators: survival/lethality rates; recovery rates (anesthesia recovery, somatic mobilization); clinical symptoms of possible intoxication with the gas mixture during inhalation exposure. The surviving animals were then monitored for 4 days to evaluate their health and behavioral performance. Upon completing the observation period, the animals were euthanized.Results. After artificially-induced blood loss, all the non-survivors died within 1.5–8 hours after the operation. In group 1 (post-conditioning in medium No. 1), the lethality of laboratory animals amounted to 4 individuals out of 24 (16%); in group 2 (post-conditioning in medium No. 2) — 2 individuals out of 24 (8%). In the control group, the lethality rate was significantly higher — 10 animals out of 24 (42%). The surviving animals demonstrated no lethality or morbidity within 4 days after the exposure. Analysis of outcomes between experimental groups and controls revealed that the significance of differences in the lethality index between group 1 and control (by Fisher’s two-sided criterion) comprised p = 0.06; between group 2 and control — p = 0.017. When the statistical “power” of the experimental group was increased (by combining samples 1 and 2), the significance of differences in outcomes in this group compared to the control accounted for p < 0.001.Conclusion. The conducted studies confirmed the hypothesis about the pronounced antihypoxic effect of argon, which significantly increased the survival rate of experimental animals after massive artificially-induced blood loss.