Experimental studies of physiological and pathological effects induced by systemic hypoxia and the hypoxia-reoxygenation model in rats

Abstract

We attempted to make a basic model to investigate a series of factors that induce histological changes in systemic hypoxia-reoxygenation injuries. At first, we set the experimental conditions for hypoxia and the hypoxia-reoxygenation models as follows: respiration volume: 1.5 ml/stroke, respiratory frequency: 80 times/min, oxygen concentration: 14%. Next, Male SPF Wistar rats were anesthetized with pentobarbital sodium. For artificial ventilation, a cannula was inserted in the trachea and connected to the rodent ventilator through two flow meters to allow mixing of 100%N2 and 95%O2-5%CO2 gases at a desired ratio. The influence of hypoxia-reoxygenation was studied and evaluated histologically and biochemically. The rats were placed under the hypoxic condition for either 3 or 6 hr. Then, oxygen partial pressure was restored to 21% followed by reoxygenation for either 3 or 6 hr. Then the rats were sacrificed, and the pituitary, adrenals, heart, stomach and kidneys were removed. The results were as follows: 1) GPT activities were increased by a load of hypoxia, but no influence of reoxygenation was detected. 2) Under the condition of experimental hypoxia, the weights of the pituitary and adrenals increased significantly. 3) The histological findings indicated that 6-hr hypoxia followed by 3-hr reoxygenation induced hypoxia-reoxygenation injuries mostly affecting the anterior pituitary and adrenal medulla.