title: The evolution of beta-adrenergic dysfunction during the induction of canine cobalt cardiomyopathy.
abstract: This study was designed to investigate the changes in the beta adrenergic system during the induction of cobalt cardiomyopathy in dogs. Cobalt sulphate, at a dose of 5 mg X kg-1 X day-1 was administered intravenously with a low protein, low thiamine diet to 13 dogs. The percentage change of the left ventricular minor axis with systole by echocardiogram (% delta D) and dP/dtmax were used to monitor left ventricular function. Noradrenaline (NA) was measured in 24 h urine samples. Left ventricular (LV) free wall biopsies were assayed for noradrenaline (LV-NA), cyclic AMP, cyclic GMP and dopamine beta hydroxylase (LV-DBH). Lymphocytes were assayed for beta-receptor density. All dogs were studied at baseline and seven were studied after a midpoint cumulative dose of 60 to 90 mg X kg-1 of cobalt; the remaining six dogs were studied when they were in heart failure and had received more than 110 mg X kg-1. During the induction of heart failure the heart rate rose from 112 +/- 6 (means +/- SE) at baseline to 154 +/- 9 at the midpoint and 153 +/- 9 (both P less than 0.05) at the final measurement while the % delta D fell from 35 +/- 2% to 31 +/- 3% and 23 +/- 2% (P less than 0.05) and dP/dt fell from 333 +/- 40 kPa X s-1 at baseline to 254 +/- 46 kPa X s-1 (P less than 0.05) and 207 +/- 33 kPa X s-1 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D009202:Cardiomyopathies / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D002395:Catecholamines / Q000378:metabolism; D003035:Cobalt; D004285:Dogs; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D006439:Hemodynamics; D009206:Myocardium / Q000378:metabolism; D009712:Nucleotides, Cyclic / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism / Q000502:physiology*
chemical_list: D002395:Catecholamines; D009712:Nucleotides, Cyclic; D011943:Receptors, Adrenergic, beta; D003035:Cobalt; D004299:Dopamine beta-Hydroxylase; C026305:cobalt sulfate