MEAL-INDUCED RISE IN RESTING ENERGY-EXPENDITURE IN PATIENTS WITH COMPLETE CERVICAL SPINAL-CORD LESIONS

Central activation of the sympathoadrenal system is generally consider ed to be an essential component of the mechanisms whereby food ingesti on stimulates resting energy expenditure. The functional importance of such sympathoadrenal stimulation has been demonstrated primarily in a nimals. To the extent that central sympathoadrenal stimulation is requ ired for normal human nutrient-induced thermogenesis, this process sho uld be defective in patients with complete cervical spinal cord lesion and severed connection between the central nervous system and the per ipheral sympathetic nerves. Consequently, respiratory gas exchange was measured by indirect calorimetry in 9 tetraplegic patients and in 6 h ealthy individuals. Measurements were performed before and 2 hours aft er ingestion of a standardised mixed meal (40% of basal 24 h energy re quirements). The basal energy expenditure was 64 +/- 4 watts in the te traplegic patients and 79 +/- 6 watts in the controls. After the meal, energy expenditure increased on average by 17 +/- 2 watts or 26 +/- 3 % of the basal values in the patients and by 14 +/- 2 watts or 19 +/- 3% in the healthy controls (NS). The thermic effect of the meal, ie th e rise in energy expenditure expressed in percent of the meal's energy content, was 5.5 +/- 0.7% in the patients and 3.8 +/- 0.6% in the con trols (NS). Plasma concentrations of noradrenaline were low in the tet raplegic patients (0.3-0.4 nmol/l) compared to the healthy controls (1 .1-1.4 nmol/l), p < 0.02. It is concluded that nutrient-induced thermo genesis in tetraplegic patients with low sympathoadrenal activity is n ot diminished compared to healthy controls. The findings indicate that efferent sympathoadrenal stimulation from the brain is not a causal n ecessity for nutrient-induced thermogenesis in man.