title: Oxyhaemoglobin equilibrium and chronic beta-adrenoceptor blockade in coronary heart disease.
abstract: In 20 patients with coronary heart disease the effect of long-term beta-adrenergic receptor blockade on the haemoglobin oxygen equilibrium was investigated. Study patients received alprenolol 200 mg twice daily for 12-41 months (mean: 24 months) as a secondary preventive measure following a myocardial infarction. While on and again following gradual withdrawal of alprenolol, the patients performed a maximum bicycle ergometer test. Haemoglobin oxygen affinity as expressed by the P50 value, 2,3-diphosphoglycerate (2,3-DPG) and carbon monoxide haemoglobin were measured before and following exercise. Pre-exercise P50 decreased from 25.2 +/- 0.3 mm Hg (mean +/- s.e. mean) while on beta-adrenoceptor blocker to 24.6 +/- 0.4 mm Hg in the off-treatment state (P less than 0.05). Five minutes after stopping exercise P50 was 25.1 +/- 0.3 in patients taking alprenolol as compared to 24.7 +/- 0.3 after withdrawal of the drug (P less than 0.01). It is concluded that the slight decrease in haemoglobin oxygen affinity in long-term treatment with alprenolol, which is observed in the present study probably is without clinical bearing. The question should be further elucidated by analysis of coronary sinus blood samples.
mesh_terms: D019794:2,3-Diphosphoglycerate; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D003327:Coronary Disease / Q000097:blood* / Q000188:drug therapy; D004163:Diphosphoglyceric Acids / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism*; D005082:Physical Exertion
chemical_list: D000319:Adrenergic beta-Antagonists; D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D010108:Oxyhemoglobins; D019794:2,3-Diphosphoglycerate