Effect of xylazine on indices of myocardial contractility in the dog.
Changes in cardiac contractility were assessed by 2 indices of myocardial contractile performance (dP/dt/Kp max, V max). Both indices demonstrated an initial positive inotropic response to intravenous administration of xylazine (1.1 mg/kg). This positive inotropic effect was followed by a return to or significant decrease from base-line recordings in these contractile indices at faster heart rates or later times following xylazine administration. In addition, an increase in heart rate in control dogs was accompanied by a rise in both dP/dt/Kp max and V max, confirming earlier evidence of the Bowditch staircase effect in the intact dog ventricle.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D013843:Thiazines / Q000494:pharmacology*; D014991:Xylazine / Q000494:pharmacology*
D013843:Thiazines; D014991:Xylazine