Circulatory responses of the dog to acute isovolumic anaemia in the presence of high-grade adrenergic beta-receptor blockade.
The haemodynamic responses to isovolumic anaemia (dextran-for-blood exchange) were studied in seven dogs pretreated with propranolol 20 mg/kg body weight for 3 weeks. Adrenergic beta-receptor blockade did not prevent significant increases in heart rate (up to 19%). Cardiac output increased by about 20% while systemic vascular resistance decreased by the same proportion. Oxygen extraction increased from 24% to 35% and this was reflected by a decrease in mixed venous PO2 by 1.2 kPa. The modest hyperdynamic response of the circulation to haemodilution in the presence of high-grade adrenergic beta-receptor blockade is in sharp contrast with the large hyperdynamic response that has been reported in its absence and indicates that normal compensatory mechanisms are considerably impaired.
D000208:Acute Disease; D000740:Anemia / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D000818:Animals; D001810:Blood Volume; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D006438:Hemodilution / Q000009:adverse effects*; D006439:Hemodynamics / Q000187:drug effects*; D010100:Oxygen / Q000097:blood; D011433:Propranolol / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
D011433:Propranolol; D010100:Oxygen