PERIPHERAL AFFERENT STIMULATION OF DECENTRALIZED SYMPATHETIC NEURONS ACTIVATES LIPOLYSIS IN SPINAL CORD-INJURED SUBJECTS

Spinal cord-injured (SCI) subjects exhibit a normal lipolytic rate des pite the failure of centrally mediated sympathoexcitatory stimuli to a ctivate lipolysis. Peripheral afferent stimulation below the lesion le vel induces an exaggerated autonomic reaction in SCI with lesion level s above T5, ie, so-called autonomic dysreflexia. The metabolic effects of Induced dysreflexia were investigated in five SCI subjects (age, 3 5 +/- 8 years; duration of paresis, 15 +/- 7.5 years [mean +/- SD]; le sion level, T3 to T4, n = 2, C7, n = 3) following bladder stimulation. Subcutaneous glycerol concentrations were measured by microdialysis a bove and below the lesion level. Diurnal plasma noradrenaline (NA) and adrenaline levels were continuously monitored in seven SCI subjects ( lesion level T3 to T4, n = 2; C4 to C7, n = 5). Bladder stimulation re sulted in an increased mean arterial pressure ([MAP] 81 +/- 8 to 114 /- 11 mm Hg, P < .05), a decreased heart rate (70 +/- 3 to 54 +/- 4 be ats/min; P < .05), and an increased plasma NA (0.70 +/- 0.49 v 3.27 +/ - 1.56 nmol/L P < .05). Interstitial glycerol was increased in the dec entralized region (89 +/- 12 to 135 +/- 21 mu mol/L, P < .05), whereas no reaction was found in the centrally innervated region. Plasma conc entrations of glycerol and insulin increased. Diurnal monitoring showe d periods of increased plasma NA sufficient to induce lipolysis (> 1.4 nmol/L) during 20% of the registration period, The data suggest that peripheral afferent stimulation below the lesion level increases NA re lease and activates lipolysis and that frequent episodes of activation are found in SCI subjects with tetraplegia or high paraplegia. Copyri ght (C) 1997 by W.B. Saunders Company.