Thoracic duct lymph in conscious dogs at rest and during changes of physical activity.

In conscious dogs with a thoracic duct-venous shunt, lymph flow (LF), protein concentration (LP), transported protein (LTP), albumin concentration (LA), globulin concentration (LG), albumin to globulin ratio (LAG), plasma disappearance rate of labelled albumin (k), plasma volume (PV) and intravascular protein pool (IVP) were studied at rest, during walking and muscle relaxation induced by guajacolglycerinether. At rest, LF approximated 50 mul/min-kg and LTP 1.55 mg/min-kg. LF and LTP correlated positively with the state of physical activity. LP was 54%, LA 67%, LG 43%, but LAG 156% of the plasma values; k was 0.00228. Relaxation reduced LF by 34%, LTP by 31%, LAG by 7% and the lymph concentration of i.m. applied labelled albumin by 54%. PV, IVP and k were not changed significantly. Walking enhanced LF by 100%, LTP by 50% and LAG by 25%. LP was decreased by 15%. PV, IVP and k were not changed significantly. Control data suggest a significant influence of anaesthesia on thoracic duct lymph flow, composition and protein transport. Spontaneous and experimental changes of thoracic duct lymph may be explained by changes of the activity of the "tissue pump". An extravascular fluid and protein pool would seem to be accumulated at rest and emptied during exercise.