Canine cardiovascular responses to endotracheally and intravenously administered atropine, isoproterenol, and propranolol.
This study compared canine cardiovascular responses observed after endotracheally administered atropine, isoproterenol, and propranolol to those observed following IV administration. Acetylcholine and isoproterenol dose response curves for arterial pressures and heart rate were established following IV boluses of each drug. Once the dose response curves were established, atropine and propranolol were administered endotracheally and intravenously in different groups to alter the established dose response curves. The time required for endotracheally and intravenously administered atropine and propranolol to inhibit 50% of the mean arterial pressure response following an IV infusion of acetylcholine and isoproterenol, respectively, was determined. Atropine and propranolol administered by either route significantly altered the arterial pressure response to acetylcholine and isoproterenol (P less than .05), respectively. Atropine altered the heart rate response to acetylcholine when administered by either route (P less than .05). IV-administered propranolol altered the heart rate response to isoproterenol (P less than .05); endotracheally administered propranolol did not. Atropine administered IV inhibited 50% of the mean arterial pressure response during an acetylcholine infusion within 21 seconds, and within 48 seconds following endotracheal administration. Propranolol administered intravenously inhibited 50% of the mean arterial pressure response during an isoproterenol infusion within 23 seconds, and within 49 seconds following endotracheal administration. The arterial pressure and heart rate responses immediately following endotracheally and intravenously administered isoproterenol also were measured and compared. The arterial pressure and heart rate responses after endotracheally administered isoproterenol were much less than those following IV administration (P less than .005). In dogs the pharmacological effects following endotracheally and intravenously administered atropine and propranolol are similar, while the effects of endotracheally and intravenously administered isoproterenol differ greatly.
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D007275:Injections, Intravenous; D007442:Intubation, Intratracheal; D007545:Isoproterenol / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D013997:Time Factors
D001285:Atropine; D011433:Propranolol; D007545:Isoproterenol