Haemodynamic and metabolic effects of combined adrenergic alpha- and beta-receptor blockade with labetalol in the exercising human forearm.
At rest supine acute intravenous administration of the combined adrenergic alpha- and beta-receptor blocking compound labetalol (1 mg/kg body weight) to young, healthy, male subjects, produced a clear-cut fall in arterial blood pressure. During dynamic forearm exercise, forearm blood flow decreased by 17.2%, and calculated vascular resistance increased by 11.3% after labetalol. Forearm oxygen uptake decreased (14.6%), suggesting an increased mechanical efficiency. Lactate release from the exercising forearm decreased (17.6%), probably because of the beta-receptor blockade. Forearm uptake of glucose and free fatty acids remained unchanged. Arterial blood glucose concentration attained a higher level after labetalol. Arterial plasma concentration of FFA was reduced during exercise and post-exercise probably because beta-receptor mediated lipolysis was antagonized.
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D004983:Ethanolamines / Q000494:pharmacology*; D005542:Forearm / Q000098:blood supply; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007741:Labetalol / Q000494:pharmacology*; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D011943:Receptors, Adrenergic, beta / Q000187:drug effects
D001786:Blood Glucose; D004983:Ethanolamines; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D007741:Labetalol