Significance of the extracellular bicarbonate buffer system to anaerobic glycolysis in hypoxic muscle.
1. The influence of the carbon dioxide-bicarbonate buffer system on anaerobic energy production during severe hypoxia was studied in isolated right hemidiaphragms of rats.--2. When the tissue was incubated in a Ringer solution containing 25 mM HCO-3 aerated with 7% CO2 in N2 at pH 7.4, the lactate production and lactate content of the tissue increased.--3. At an extracellular (tissue bath) pH OF 6.9 the lactate production was stimulated when carbon dioxide and bicarbonate were changed to 19% and 25 mM, respectively. This stimulatory effect disappeared when these values were lowered to 7% and 7 mM.--4. At pH 7.4 the stimulatory effect of the carbon dioxide-bicarbonate system persisted when the buffer value was lowered from 60 to 3 mM by changing the system from an open (i.e. continuous gas equilibration) to a closed one (i.e. without any gas phase). Decreasing the glucose in the media from 22 to 0 mM reduced the lactate production and abolished the stimulatory effect of the carbon dioxide--bicarbonate system.--5. There was no direct effect of this system on the glycolytic enzymes (i.e. lactate production and activity of phosphofructokinase of homogenates).
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism* / Q000494:pharmacology; D002021:Buffers; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology; D003964:Diaphragm / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006019:Glycolysis; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism*; D007773:Lactates / Q000096:biosynthesis; D008297:Male; D009132:Muscles / Q000378:metabolism*; D051381:Rats
D001639:Bicarbonates; D002021:Buffers; D007773:Lactates; D002245:Carbon Dioxide; D005947:Glucose