The effects of blood CO2 reaction rates on CO2 removal from muscle in exercised trout.

The purpose of this study was to examine the relative importance of some of the factors potentially limiting carbon dioxide (CO2) removal from the white muscle in the rainbow trout following exhaustive exercise. Inhibition of red blood cell carbonic anhydrase (CA) activity by acetazolamide (Az) infusion following exercise caused a large increase in both arterial and muscle PCO2 indicating retention of CO2 in the animal. Despite the increase in muscle PCO2, there was no significant decrease in muscle pH in Az-treated fish, probably due to the relatively high buffer capacity of white muscle. The presence of CA in the plasma had a transient, significant effect on blood PCO2 and pH, but no significant effect on muscle PCO2 or pH. Thus, CA treatment transiently enhances CO2 removal from the animal following exercise, but the extracellular catalysis of the CO2 reactions in the plasma does not appear to have a large impact on CO2 removal from the tissues.