Effects of hyperbaric oxygen in circulatory shock induced by splanchnic artery occlusion and reperfusion in rats

We studied the effects of hyperbaric oxygen in a severe model of circulatory shock induced by occlusion and reperfusion of major splanchnic arteries (splanchnic artery occlusion (SAO) shock). Pentobarbital-anesthetized rats subjected to total occlusion of the superior mesenteric and the celiac arteries for 40 min developed a severe shock state, resulting in a uniformly fatal outcome after release of the occlusion. Exposure to hyperbaric oxygen at 2 ATA (atmosphere absolute) (1 ATA = 0.1 MPa) was initiated immediately after reperfusion. SAO shock rats exposed to hyperbaric oxygen maintained mean arterial blood pressure at significantly higher values throughout the postreperfusion period compared with untreated SAO shock rats (p < 0.01), with final mean arterial blood pressures of 88 ± 9 and 51 ± 4 mmHg, respectively. Treatment with hyperbaric oxygen attenuated the increase in plasma activities of the lysosomal hydrolase cathepsin D(p < 0.05), and diminished the increase of hematocrit (p < 0.01 from untreated shock rats). Splanchnic occlusion shock rats treated with hyperbaric oxygen also exhibited a significantly higher survival rate than the untreated shock group (77 vs. 0%, respectively; p < 0.01). Our results suggest that the beneficial effects of exposure to hyperbaric oxygen immediately after reperfusion of the splanchnic region outweigh its possible deleterious effect.Key words: mean arterial blood pressure, cathepsin D, hematocrit.