Resistance in the sheep's lymphatic system.
Saline was infused in a downstream direction into the afferent lymphatics in the metacarpal region of anesthetized sheep. The changes in inflow pressure were measured over 10 min periods with flow rates ranging from 10-2000 microliters/min. Flow rates in the physiological range generated mean pressures of about 30 mmHg and flows of 1 ml/min generated mean pressures of about 60 mmHg. Resistance was relatively high at flow rates in the range of 10-15 microliters/min but sharply decreased above that and was relatively constant at flows greater than 500 microliters/min. Adding isoprenaline (1 microgram/min) to the infusate reduced spontaneous contractile behavior in the infused system and lowered the resistance at the lower flow rates. It is concluded that the peripheral lymphatic system in the sheep offers substantial resistance to lymph flow and that substantial intralymphatic pressure is needed to return lymph from the periphery especially at higher flow rates.
Pippard
C
C
Department of Physiology, Queen's University of Belfast, Northern Ireland.
Roddie
I C
IC
D000818:Animals; D007545:Isoproterenol / Q000494:pharmacology; D008208:Lymphatic System / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011673:Pulsatile Flow / Q000187:drug effects; D012756:Sheep
D007545:Isoproterenol