Hepatic energy metabolism during ketamine and isoflurane anaesthesia in haemorrhagic shock

The effects of ketamine and isoflurane on the phosphoenergetic state of the liver during haemorrhage were investigated using 31P nuclear magnetic resonance (NMR) spectroscopy. Male Wistar rats were anaesthetized with ketamine (1.0 mg kg-1 min-1 i.v., Ket 1.0 group, or 1.5 mg kg-1 min-1 i.v., Ket 1.5 group), or isoflurane 1.4% (Iso group). Haemorrhage was induced by withdrawing blood until the mean arterial pressure was reduced to 40 mm Hg, and this pressure level was then maintained for 45 min. Hepatic energy metabolism was evaluated from the changes in adenosine triphosphate (ATP) and inorganic phosphate (Pi). The beta-ATP decrease and the Pi increase were more marked in the two Ket groups than in the Iso group. At 20 min after haemorrhage, the beta-ATP peak areas were 34%, 32% and 76%, and the Pi peak areas were 257%, 260% and 160% of their initial values in the Ket 1.0, Ket 1.5 and Iso groups, respectively. NMR data were supported by chemical assessments. These results demonstrated that, in terms of phosphoenergetic levels, a continuous administration of 1.0 or 1.5 mg kg-1 min-1 ketamine markedly decreased hepatic metabolism during haemorrhagic shock, whereas inhalation of 1.4% isoflurane mitigates the metabolic damage.