Adaptations to pressure in the RBC metabolism of diving mammals

Marine mammals are known to dive up to 2000 m and, therefore, tolerate as m uch as 200 atm. of hydrostatic pressure. To examine possible metabolic adap tations to these elevated pressures, fresh blood samples from marine and te rrestrial mammals were incubated for 2 h at 37 degreesC under 136 atm (2000 psi) of hydrostatic pressure. The consumption of plasma glucose and the pr oduction of lactate over the 2-h period were used to assess glycolytic flux in the red cells. The results indicate that glycolytic flux as measured by lactate production under pressure can be significantly depressed in most t errestrial mammals and either not altered or accelerated in marine mammals. The data also suggest that there is a significant shift in the ratio of la ctate produced to glucose consumed under pressure. Interestingly, human and dolphin blood do not react to pressure. These combined data imply a metabo lic adaptation to pressure in marine mammal RBC that may not be necessary i n human or dolphin cells due to their unique patterns of glucose metabolism . (C) 2001 Elsevier Science Inc. All rights reserved.