Esmolol: effects on isoprenaline- and exercise-induced cardiovascular stimulation in conscious dogs.
Esmolol, a recently developed ultra-short acting beta-adrenoceptor blocking agent, was evaluated in 12 conscious chronically instrumented dogs with intact autonomic reflexes. The significance of its beta 1-adrenoceptor selectivity was examined at various cardiovascular activation levels established by either incremental isoprenaline infusion or graded treadmill exercise. The observed parameters were heart rate, systolic and diastolic arterial blood pressure, left ventricular dp/dtmax, and left ventricular end-diastolic pressure. Intravenous infusion of esmolol (25 and 250 micrograms.kg-1.min-1) led to a dose-dependent reduction of the isoprenaline-induced increase in positive dp/dtmax. The concomitant increase in heart rate was suppressed to a lesser extent. Characteristically of a beta 1-selective agent, esmolol had only a slight effect on the isoprenaline-induced reduction in diastolic blood pressure. The impact of esmolol on exercise-induced hemodynamic activation was much smaller. Exercise-induced increase in positive dp/dtmax was more sensitive to beta-adrenoceptor blockade than the concomitant increase in heart rate. Diastolic blood pressure was not influenced significantly. beta-Adrenoceptor blockade was virtually reversed within 20 min of discontinuation of esmolol infusion.
Fischer
G
G
Pharmakologisches Institut Universität Wien, Austria.
Grohs
J G
JG
Raberger
G
G
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects; D003243:Consciousness / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007262:Infusions, Intravenous; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology; D010805:Physical Conditioning, Animal; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D007545:Isoproterenol; C036604:esmolol