Abstract des Autors

The purpose of the present study was to document exercise induced hyperammoniemia after blockade of the beta-adrenoreceptors and to investigate the effect of administration of branched-chain amino acids (BCAA) and glucose in these conditions. Seven dogs, chronically instrumented with a catheter in the deep jugular vein and a Doppler probe around the carotid artery were trained to perform a ten-minute treadmill exercise test. Administration of propranolol i.v. prior to exercise increases plasma ammonia at peak exercise compared with placebo (78+/-7.9 vs 25+/-5.1 micro-mol/l; p<0.05). This effect of propranolol on plasma ammonia during exercise is enhanced by the administration of BCAA (108+/-15 vs 78+/-7.9 micro-mol/l; p<0.05), and diminished by the administration of glucose (42+/-7.7 vs 78+/-7.9 micro-mol/l; p<0.05). These results suggest that increased metabolisation of BCAA is involved in the ammonia formation after beta-adrenergic blockade. Verf.-Referat