The cardiovascular effects of adrenaline, dobutamine and milrinone in rabbits using pressure-volume loops and guinea pig isolated atrial tissue.
This study evaluated the effects of milrinone, adrenaline and dobutamine with pressure-volume loops and isolated atrial tissue. Agonist dose-response curves to incremental drug infusions were acquired in 11 anesthetised rabbits using pressure-volume loops and preload recruitable stroke work indicated contractility. Agonist concentration-response curves were completed in eight guinea pig isolated atria, for effects on atrial rate and force. Adrenaline and dobutamine increased contractility (P = 0.006 and 0.044), whereas milrinone did not (P = 0.895). Only adrenaline increased myocardial stiffness (P < 0.001). Milrinone decreased vascular resistance (P < 0.001) and elicited the greatest fall in mean arterial pressure (P < 0.001) and increased ejection fraction (P < 0.001). Adrenaline decreased heart rate (P < 0.001), whereas dobutamine and milrinone increased it (P = 0.006 and 0.011). Milrinone increased the force of left atrial contraction, but its inotropic effect was weak and significantly less than with dobutamine and adrenaline (P < 0.001). Adrenaline acted as an inoconstrictor, dobutamine an inodilator and milrinone predominantly a vasodilator
Royse
C F
CF
Cardiovascular Therapeutics Unit, Department of Pharmacology and Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia.
Royse
A G
AG
Rohrlach
R
R
Wright
C E
CE
Angus
J A
JA
D000322:Adrenergic Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D020105:Milrinone / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D009924:Organ Culture Techniques; D011817:Rabbits; D014655:Vascular Resistance / Q000187:drug effects
D000322:Adrenergic Agonists; D000318:Adrenergic beta-Agonists; D002316:Cardiotonic Agents; D004280:Dobutamine; D020105:Milrinone; D004837:Epinephrine