Regional Lactic Acid Concentration in Dogs under Acute Hypoxia

摘要

Large mongrel dogs were anesthetized with sodium pentobarbital and subjected to acute hypoxia. Blood samples were simultaneously withdrawn from several regions of the body and analyzed for lactate, PO2, PCO2, and pH in order to assess the acid-base status in relation to the level of oxygen tension, with special attention focused on regional lactic acid levels. The data accumulated and presented here show that the individual responses of animals subjected to these experimental conditions vary widely, but certain trends are evident. The lactic acid concentration was shown to vary inversely with the end-tidal PO2, with a sharp increase in lactate level occurring at end-tidal oxygen tensions below 50 to 60 mm. Hg. It was also shown that under conditions of severe hypoxia there is a marked difference in lactate concentration in blood samples simultaneously withdrawn from different regions of the body. The data suggest that some organ in the abdominal visceral circulation produces lactate at a rate considerably greater than that of resting muscle under these conditions, and that this disparity may result in a reversal of the normal venous-arterial lactate gradient, with muscle apparently removing lactate from the blood. (Author)