[Effects of a hypoxic stimulus on the dependence of tissue respiration on oxygen pressure in vitro].

Experimental studies of the dynamics of energy exchange in tissues of the rats' visceral organs (brain, heart, liver, and kidney) shortly after hypoxic stimulation displayed substantial variations in the respiratory activity of visceral tissues, and Km for oxygen at the start of the follow-on reaction (24 h, 72 h, and 120 h) which subsided later on (240 h and 360 h). These were in concert with a gross decline in the intensity of visceral tissue breathing at the initial oxygen pressure in vitro and a rise at critical pO2, a decrease in the affinity of cardiac, hepatic and renal tissues for oxygen at the onset of the follow-on reaction and an increase in the affinity at subsequent time points. Throughout the period of observation, high affinity for oxygen was observed in cerebral tissues. Combination of alpha-tocopherol and the hypoxic stimulus substantially suppressed the respiratory activity in all the visceral tissues of rats at the initial oxygen pressure and in the liver and kidney, at critical pO2. Increased utilization of the low pressure oxygen was observed in the brain and the heart. More pronounced changes in tissue affinity for oxygen were revealed in the heart and the liver, and least pronounced, in the brain and the kidney. A conclusion is drawn that alpha-tocopherol can strongly influence moderation of the stressful factor on the level of tissue homogenates.