Effects of acute non-selective beta-adrenergic blockade on plasma ammonia levels in exercising dogs.
The purpose of the present study was to document exercise induced hyperammoniemia after blockade of the beta-adrenoceptors 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 mumol/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 mumol/l; p < 0.05), and diminished by the administration of glucose (42 +/- 7.7 vs 78 +/- 7.9 mumol/l; p < 0.05). These results suggest that increased metabolisation of BCAA is involved in the ammonia formation after beta-adrenergic blockade.
Matthys
D
D
University Hospital, Gent, Belgium.
Calders
P
P
Pannier
J L
JL
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000597:Amino Acids, Branched-Chain / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D000641:Ammonia / Q000097:blood* / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D002405:Catheterization, Central Venous; D002408:Catheters, Indwelling; D004285:Dogs; D005080:Exercise Test; D005947:Glucose / Q000494:pharmacology; D006339:Heart Rate; D007601:Jugular Veins; D007773:Lactates / Q000097:blood; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D010919:Placebos; D011188:Potassium / Q000097:blood; D011433:Propranolol / Q000494:pharmacology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D018608:Ultrasonography, Doppler
D000319:Adrenergic beta-Antagonists; D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D007773:Lactates; D010919:Placebos; D011943:Receptors, Adrenergic, beta; D000641:Ammonia; D011433:Propranolol; D005947:Glucose; D011188:Potassium