Charles R. Brassfield

Effects of Low Oxygen Pressure on Respiratory Phenomena.

Eight per cent oxygen mixtures were administered for a period of approximately 30 minutes to 3 dogs anesthetized with morphine and urethane. Such administration produced an initial decrease in oxygen consumption which was followed by an increase slightly in excess of normal. This excess oxygen consumption was ascribed to the increased muscular effort of augmented ventilation. The augmented ventilation increased the elimination of carbon dioxide considerably above normal. On readministration of room air there was a decrease in pulmonary ventilation, a relative retention of carbon dioxide and an oxygen consumption above normal. In one experiment the expiratory quotient rose to 2.86 during the period of oxygen lack and fell on readministration of room air to 0.24. During oxygen lack there was a substantial decrease in the carbon dioxide capacity of the blood which was promptly followed by an increase approaching or exceeding the initial carbon dioxide capacity. There was a similar increase and decrease in blood lactic acid. The blood lactic acid content at the end of the period of oxygen lack was only moderately increased. The lactic acid changes occurred earlier than and were smaller than the changes in blood carbon dioxide capacity. The lactic acid content of the testicle and the rectus femoris muscle before and after the period of oxygen lack was determined. The tissue was dropped in liquid air and a satisfactory suspension was obtained by sectioning in the frozen state with a rotary microtome. The lactic acid content of the testicle and of the muscle was increased during the period of oxygen lack. The amount of lactic acid in the muscle was greater than in the blood. In the testicle it was less than in the blood.