Objective: To study the effects of norepinephrine (NE)-induced hypertension (HT) on hepatic function and pathology after restoration of spontaneous circulation (ROSC) by cardiopulmonary resuscitation (CPR) in swine.
Methods: After 4 minutes of induced ventricular fibrillation (VF), standard CPR was carried out, and then the NE was pumped after ROSC. The survivors were then divided into two groups by the random digits table. In the HT group (n=5) the mean arterial pressure (MAP) was maintained at 130% of the baseline (MAP before VF), and in the normal pressure (NP) group (n=5) the MAP was maintained at the baseline level. At the same time, the animals of two groups received normal saline at the speed of 10 ml * kg(-1) * h(-1). Hemodynamic status was monitored and aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) were measured in blood samples obtained at baseline and at 10 minutes, 2 hours and 4 hours after ROSC. At 24 hours after ROSC, the animals were killed and the liver was removed to determine Na(+)-K(+)-ATPase and Ca(2+)-ATPase activities and pathological changes under light and electron microscopy.
Results: The heart rate (HR), MAP, cardiac output (CO) and coronary perfusion pressure (CPP) were obviously higher, while the oxygen extraction ratio was lower in the HT group than in the NP group. Compared with NP group, AST in the HT group was lower at ROSC 2 hours, 4 hours [ROSC 2 hours: (110.5+/-12.1) U/L vs. (141.8+/-8.1) U/L; ROSC 4 hours: (118.2+/-14.1) U/L vs. (175.0+/-14.3) U/L, both P<0.05], LDH was lower at ROSC 4 hours [(18.1+/-1.9) micromol * s(-1) * L(-1) vs. (20.7+/-1.9) micromol * s(-1) * L(-1), P<0.05], but ALT showed no significant difference between two groups after ROSC. ATPase activity in the HT group [Na(+)-K(+)-ATPase: (2.054+/-0.716) U, Ca(2+)-ATPase: (1.889+/-0.450) U] was a little lower than that of the NP group [Na(+)-K(+)-ATPase: (3.274+/-0.710) U, Ca(2+)-ATPase: (2.746+/-0.778) U], but without statistical significance (both P>0.05). Compared with the NP group, there was less cellular edema, necrosis or inflammatory cells infiltration, and less damaged mitochondria in HT group.
Conclusion: These data suggest that HT induced by NE helps to maintain stable hemodynamic status and oxygen metabolism, and may protect the liver in terms of function and cellular injury after CPR.