Arterial pulsation and lymph formation in an isolated sheep hindlimb preparation

1. Lymph flow was measured by cannulating metatarsal lymphatics in the sheep hindlimb. The region was perfused with warmed, heparinized, oxygenated blood via the tibio-cranial artery cannulated just distal to the hock. Constant and pulsatile perfusion pressures were compared. A cuff was inflated over the metatarsals to maintain venous pressure at 20 mmHg. 2. The lymph flow rates during constant perfusion at 80 mmHg were comparable to control flows in intact metatarsal preparations and oedema (monitored by measuring tissue volume) did not accumulate. Flow records were similar to those obtained from anaesthetized animals, lymph being expelled by regular lymphatic contractions. 3. Pulsatile perfusion using 120/60 mmHg (systolic cuff cycle 0.25 s inflation, 0.5 s deflation) did not increase the rate of lymph flow. Increasing the pulse pressure to 100 mmHg (150/50 mmHg) produced a 20% increase in flow but this was not statistically significant. The cuff deflation time was also increased (1 s inflation, 1 s deflation) using 120/60 mmHg but this had little effect. 4. It may be concluded that arterial pulsation is not important for lymph formation in this preparation.