Lymphatic Transport of Cellular Enzymes from Muscle into the Intravascular Compartment

Abstract

In an experimental study, employing anaesthetized dogs, it was investigated whether cellular enzymes from peripheral skeletal muscle get into the circulating blood by diffusion across capillary membranes or by lymphatic transport. In the experimental group 1, the animals were anaesthetized only. The plasma activities of the four enzymes measured — lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, creatine kinase did not show any mentionable change during a time period of 6 h. In group 2 one hind limb of each animal was moved passively for 1 h. Alanine aminotransferase remained unchanged in plasma, the activities of the three other enzymes increased significantly. In group 3 one hind limb was made hypoxic by clamping the femoral blood vessels for 1 h. No activity changes were observed. When the period of hypoxia was followed by a 1-hour period of passive movement in group 4, the alterations in plasma activities were almost identical to those observed in group 2. In group 5 the experimental procedure was as in group 4, in addition the lymph from the thoracic duct was quantitatively withdrawn. The enzyme activities in plasma revealed a tendency to decrease rather than increase. Lymph flow increased significantly as well as the lymphatic activities of those enzymes which have high intracellular activities in muscle. The results prove, that enzymes from muscle are transported from the interstitial into the intravascular compartment mainly by lymphatic transport. Indications were found that the interruption of blood flow in one hind limb did not result in an enzyme release from muscle cells. It is discussed how changes in lymph flow, occurring during physical exercise for example, affect enzyme activities in plasma.

Effect of Transient Hypoxia in Skeletal Muscle on Enzyme Activities in Lymph and Plasma

“…It was further shown that the plasma enzyme response to spontaneous running exercise in conscious dogs is quantitatively similar to the plasma Tab, l. Enzyme activities in Iymph and plasma (U/l; x ± SEM) and lymph-plasma activity ratio (x ± SEM) in order of dimishing lymph-plasma activity ratio. Probabilities of significance between the muscles: * 2p < 0.05 *** 2p < 0.001 enzyme response evoked by passive movement of the hind limb in anaesthetised dogs (10,33,34,35,36).…”

“…During periöds of physical activity or passive motiöri these activities reach the blood via ductus thoracicus in considerable amount. Recent investigations on changes in the flow of duptus thoracicus Iymph, evoked by passive motion pf the hind limb in äriaesthetised dogs, have shown that these changes in fact can traced back nearly exclusively to Iymph propulsion from the passively moved muscle by action of the tissue pump (10,15). These observations then simply point to the importance of alterations of Iymph flow from muscle for the adjustment of the level pf cellular enzymes of musculär prigin in plasma.…”

“…Even ünder physiological conditions enzyme activities in the ductus thoracicus, and leg lymph are several fold higher compared to plasma (10)(11)(12)(13).…”

“…Hitherto, however, lymph seems to be a forgotten organ and only a few grpups have paid attention to the effect of physical activity on enzyme activities in this extracellular fluid compartment (10,(21)(22)(23)(24)(25)(26)(27).…”

Catalytic Enzyme Activity Concentration in Plasma of Man, Sheep, Dog, Cat, Rabbit, Guinea Pig, Rat and Mouse. Approach to a Quantitative Diagnostic Enzymology. I. Communication

“…The data are expressed äs the mean and include quality control measurements from 1. c. (14,15,28), in which catalytic activities were determined in lymph, tissue and erythrocytes. Daily quality control for the other enzymes was established with cornmercial control sera of varying batch number.…”