Hideki Niwa

The rate of lipid oxidation in septic rat models

In order to examine the rate of lipid oxidation in sepsis, lipid infusion studies were carried out using two experimental models of septic rats, namely; an endotoxin group, and a cecum ligation and puncture group. Following the administration of glucose at a caloric amount equivalent to the measured resting energy expenditure (REE), the respiratory quotient (RG) values dropped promptly in the control group, but decreased only slightly in the septic groups. Following the administration of a lower dose of glucose (0.5 kcal/100 g B.W./hr), however, a lipid infusion promptly decreased the value of RQ in the septic groups. These results suggest that lipid oxidation was depressed in the septic groups and that the degree of depression was greatly influenced by the relationship between REE and the amount of administered glucose.

Studies on the energy expenditure following surgical stress. I: The effects of the severity of stress and the administration of nutrients

Energy expenditure was studied in male Donryu rats, following two types of surgical stress, namely, laparotomy and burns. The rats with burns were subsequently fasted for 6 hours, by which time the resting metabolic expenditure (RME) became significantly decreased (84.3±9.5 per cent), as when compared to the pre-burn value (100 per cent), then increased 24 hours after the burn (132.9±10.1 per cent). The RME in burned rats receiving an intravenous infusion of electrolyte fluid, slightly increased 6 hours after the burn (109.0±15.8 per cent) and was almost identical to the RME in rats fedad libitum for 24 hours after the burn. Rats with burns, that were given intravenous infusions of electrolytes and nutrients (TPN) already had a high RME value (134.6±7.0 per cent) 6 hours after the burn. In laparotomized rats fedad libitum, no obvious changes in energy expenditure were observed 6 hours or 24 hours after the laparotomy, however, rats receiving TPN showed a moderately increased RME 6 hours after the laparotomy (113.9±3.4 per cent, p<0.05) which returned to the pre-stress level 24 hours post-operatively. These results confirmed that a phase of decreased RME (ebb phase), followed by a phase of increased RME were clearly observed after severe surgical stress, which indicated that appropriate treatments could shorten or extinguish the ebb phase.

Studies on the energy expenditure following surgical stress. II: The correlation between energy expenditure and hormonal changes

The correlation between energy expenditure and hormonal changes following surgical stress was studied using rats. Blood concentrations of catecholamine, insulin, corticosterone, glucagon, T3, and T4 were compared between the rats (IIa and IIb) in the ebb phase and those (III and IV) in the flow phase, 6 hours after being inflicted with a burn. Noradrenaline was higher, though not significantly, and glucagon was significantly higher in the latter groups than in the former groups. When glucagon was administered to the rats in the ebb phase, RME increased significantly. From these results, it is suggested that glucagon plays an important role in the transition from ebb phase to flow phase.