Constriction of isolated collecting lymphatic vessels in response to acute increases in downstream pressure

摘要: Collecting lymphatic vessels generate pressure to transport lymph downstream the subclavian vein against a significant head. To investigate their response elevated pressure, collecting containing one valve (incomplete lymphangion) or two valves (complete were isolated from rat mesentery and tied glass cannulae capable of independent control. Downstream was selectively raised various levels, either stepwise ramp-wise, while keeping upstream constant. Diameter positions tracked under video microscopy, intralymphangion measured concurrently with servo-null micropipette. Surprisingly, potent constriction occurred in gradient due (1) pressure-dependent myogenic (2) frequency-dependent decrease diastolic diameter. The index (-3.3 ± 0.6, mmHg) greater than that arterioles exposed uniform increases (i.e. pressures together). Additionally, transmitted vessel segment even though it protected changes by closed intraluminal valve; conducted blocked loading only pressurized half ML-7 (0.5 mm) block contraction, cromakalim (3 μm) hyperpolarize muscle layer. Finally, we provide evidence is important maintain normal closure during each contraction cycle face an adverse gradient, which probably protects capillaries backflow.