Effects of systemic arterial hypoperfusion on splanchnic hemodynamics and hepatic arterial buffer response in pigs

The hepatic arterial buffer response (HABR) tends to maintain liver blood f low under conditions of low mesenteric perfusion. We hypothesized that syst emic hypoperfusion impairs the HABR. In 12 pigs, aortic blood flow was redu ced by cardiac tamponade to 50 ml.kg(-1).min(-1) for 1 h (short-term tampon ade) and further to 30 ml.kg(-1).min(-1) for another hour (prolonged tampon ade). Twelve pigs without tamponade served as controls. Portal venous blood flow decreased from 17 +/- 3 (baseline) to 6 +/- 4 ml.kg(-1).min(-1) (prol onged tamponade; P = 0.012) and did not change in controls, whereas hepatic arterial blood flow decreased from 2 +/- 1 (baseline) to 1 +/- 1 ml.kg(-1) .min(-1) (prolonged tamponade; P = 0.050) and increased from 2 6 1 to 4 +/- 2 ml.kg(-1).min(-1) in controls (P = 0.002). The change in hepatic arteria l conductance (DeltaC(ha)) during acute portal vein occlusion decreased fro m 0.1 +/- 0.05 (baseline) to 0 +/- 0.01 ml.kg(-1).min(-1).mmHg(-1) (prolong ed tamponade; P = 0.043). In controls, DeltaC(ha) did not change. Hepatic l actate extraction decreased, but hepatic release of glutathione S-transfera se A did not change during cardiac tamponade. In conclusion, during low sys temic perfusion, the HABR is exhausted and hepatic function is impaired wit hout signs of cellular damage.