Effects of the partial beta 1-adrenergic agonist, xamoterol, on hemodynamics and regional myocardial function during acute coronary occlusion in dogs.
Xamoterol is a partial beta 1-adrenergic agonist that has combined beta 1-stimulating and beta 1-blocking actions. We studied the effects of xamoterol on hemodynamics and regional left ventricular (LV) function after circumflex coronary artery occlusion in eight anesthetized dogs. Left ventricular systolic wall thickening (%WT: sonomicrometry) was measured in nonischemic, marginal, and ischemic zones. Xamoterol (350 micrograms/kg i.v.) increased the maximum LV pressure (dP/dt) by 62% and aortic flow (AOF) by 52% and decreased LV end-diastolic pressure (EDP) but did not change heart rate (HR) and peak LV pressure (LVP). Xamoterol increased %WT in nonischemic (23.6 +/- 2.3 to 35.1 +/- 2.6%, p less than 0.05) and marginal (5.0 +/- 0.6 to 12.0 +/- 1.5%, p less than 0.05), but not in the ischemic region [-5.7 +/- 0.7 to -2.7 +/- 0.3%, not significant (NS)]. The beta 1-blocking action of xamoterol was evaluated. Xamoterol significantly attenuated the increase in HR and maximum dP/dt caused by isoproterenol (0.1 microgram/kg/min). %WT in each region was maintained at the level caused by xamoterol after isoproterenol. Thus, xamoterol improved cardiac function, yet prevented excessive stimulation by catecholamine in the presence of acute myocardial ischemia.
Miura
T
T
Second Department of Internal Medicine, Yamaguchi University School of Medicine, Ube, Japan.
Matsuzaki
M
M
Toma
Y
Y
Yonezawa
F
F
Kohno
M
M
Katayama
K
K
Ozaki
M
M
Kumada
T
T
Kusukawa
R
R
D000208:Acute Disease; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000758:Anesthesia; D000818:Animals; D003327:Coronary Disease / Q000503:physiopathology*; D004285:Dogs; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D011412:Propanolamines / Q000494:pharmacology*; D017307:Xamoterol
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D017307:Xamoterol; D007545:Isoproterenol