Lipolysis and lipid oxidation in cirrhosis and after liver transplantation

On the basis of the finding that plasma glycerol concentration is not contr olled by clearance in healthy humans, it has been proposed that elevated pl asma free fatty acid (FFA) and glycerol concentrations in cirrhotic subject s are caused by accelerated lipolysis. This proposal has not been validated . We infused 10 volunteers, 10 cirrhotic subjects, and 10 patients after or thotopic liver transplantation (OLT) with [1-C-13]palmitate and [H-2(5)]gly cerol to compare fluxes (R-a) and FFA oxidation. Cirrhotic subjects had hig her plasma palmitate (52%) and glycerol (33%) concentrations than controls. Palmitate R-a was faster (1.45 +/- 0.18 vs. 0.85 +/- 0.17 mu mol . kg(-1) . min(-1)) but glycerol R-a and clearance slower (1.20 +/- 0.09 vs. 1.90 +/ - 0.24 mu mol . kg(-1) . min(-1) and 21.2 +/- 1.2 vs. 44.7 +/- 4.9 ml . kg( -) . h(-1), respectively) than in controls. After OLT, plasma palmitate and glycerol concentrations and palmitate R-a did not differ, but glycerol R-a (1.16 +/- 0.11 mu mol . kg(-1) . min(-1)) and clearance (26.7 +/- 2.4 ml . kg(-) . h(-1)) were slower than in controls. We conclude that 1) impaired reesterification, not accelerated lipolysis, elevates FFA in cirrhotic subj ects; 2) normalized FFA after OLT masks impaired reesterification; and 3) p lasma glycerol concentration poorly reflects lipolytic rate in cirrhosis an d after OLT.