title: Haemodynamic and metabolic effects of xamoterol in exercising dogs.
abstract: The effects of xamoterol on the haemodynamic adaptation to graded treadmill exercise were evaluated during five subsequent cycles in chronically instrumented dogs. At rest xamoterol, 0.2 mg/kg i.v., preferentially showed a positive inotropic effect, whereas 1 mg/kg i.v. also exhibited a marked chronotropic effect. The cardiac output and left ventricular power increased dose dependently. The mean left atrial pressure and total peripheral resistance decreased concomitantly. Xamoterol did not produce a noteworthy decrease in heart rate or positive dp/dtmax during exercise, even at a dosage of 1 mg/kg. A beta-adrenoceptor blocking effect could only be seen from the diminution of the exercise-induced changes in heart rate, dp/dtmax, cardiac output, left ventricular power and total peripheral resistance. Determination of the blood glucose, lactate and pyruvate levels before the start of each exercise cycle revealed that the drug induced a decrease in blood glucose and an increase in blood pyruvate. Thus, xamoterol exerted a dose-dependent sympathomimetic effect in dogs at rest. However, there was little evidence for a beta-adrenoceptor blocking action even at higher work loads, although preliminary experiments in conscious dogs showed that xamoterol shifted the isoprenaline dose-response curve to the right by a factor of 1.31 (0.2 mg/kg) and 3.05 (1 mg/kg).
authors: Pharmakologisches Institut Universität Wien, Austria.
authors: G
authors: G
authors: Fischer
authors: W
authors: W
authors: Schneider
authors: J G
authors: JG
authors: Grohs
authors: S
authors: S
authors: Ehrendorfer
authors: G
authors: G
authors: Raberger
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002302:Cardiac Output / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D005947:Glucose / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology; D007773:Lactates / Q000378:metabolism; D008297:Male; D010805:Physical Conditioning, Animal; D011412:Propanolamines / Q000494:pharmacology*; D011773:Pyruvates / Q000378:metabolism; D014655:Vascular Resistance / Q000187:drug effects; D017307:Xamoterol
chemical_list: D001786:Blood Glucose; D007773:Lactates; D011412:Propanolamines; D011773:Pyruvates; D017307:Xamoterol; D005947:Glucose; D007545:Isoproterenol