Effect of transient hypoxia in skeletal muscle on enzyme activities in lymph and plasma

The effect of hypoxia lasting one hour on the hind leg muscle of anaesthetised dogs was investigated. Ten enzyme activities in plasma and leg lymph, and the lymphatic transport of these enzymes were investigated. Enzymes with high activity in muscle, like creatine kinase, lactate dehydrogenase, malate dehydrogenase and adenylate kinase only show an increase in the plasma, if lymph--propulsed by passive motion of the hind leg--can reach the intravascular space. This effect is independent of transient hypoxia. Depending on the level of enzyme activity in the muscle, the activity in leg lymph is up to 6-fold higher than in plasma. Enzymes from muscle have to be transported into the blood by lymph flow and not via a direct interstitial-venous entry. The results are discussed especially with respect to enzyme activity changes in plasma during physical exercise.