Net transcapillary (lymphatic) water, total protein, and albumin fluxes (expressed as plasma clearances into lymph) from the liver and intestine were estimated in 25 patients with hepatic cirrhosis and portal hypertension undergoing abdominal operation from a "mixture formula" (see text) based on direct measurement of thoracic duct lymph flow and protein content of plasma, liver, intestinal, and thoracic duct lymph. In the digestive tract, increased water flux (4.20 ± 0.88 ml/min, mean ± SE) was unaccompanied by increased protein leakage (0.42 ± 0.10 ml/ min) (r = 0.22), whereas in the cirrhotic liver, protein flux (1.82 ± 0.44 ml/min) closely paralleled water movement (2.8 ± 0.59 ml/min) (r = 0.95) but with persistence of permselectivity. These findings point to a predominant dissipative process of protein transport (diffusion or vesicular turnover) in the splanchnic capillary network and a primarily convective process (solvent drag) in the hepatic sinusoidal microcirculation. Further, splanchnic capillaries and hepatic sinusoids apparently resist "stretching" even under the rigor of long-standing portal hypertension, and heightened capillary permeability is not a significant factor in the pathogenesis of cirrhotic ascites.
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