The effect of acetazolamide on myocardial carbon dioxide space

Carbon dioxide, water and vascular space were measured in the heart muscle of the dog before and after the administration of acetazolamide. In contrast to the skeletal muscle whose CO2 space was markedly reduced by acetazolamide, cardiac muscle CO2 space was only minimally reduced. This suggests that cardiac muscle does not have extravascular carbonic anhydrase. Its presence in skeletal muscle and absence in cardiac muscle probably relates to the differences in cell size between the two types of muscle and their differing degree of vascularity.