Ludders J W, Reitan J A, Martucci R, Fung D L, Steffey E P
Am J Vet Res. 1983 Jun;44(6):996-9.
To quantitate acetylpromazine-induced alpha-adrenergic receptor blockade, phenylephrine was infused into dogs. The amount of phenylephrine necessary to increase the mean arterial blood pressure (MAP) 50% above base line, with or without the prior administration of acetylpromazine, served to quantify the degree of acetylpromazine-induced alpha-adrenergic receptor blockade. Seven dogs were anesthetized with thiopental, maintained on halothane in oxygen, and mechanically ventilated. All infusions were made through a catheter in the cephalic vein. Continuous recordings were made of MAP and a lead II ECG. After induction of anesthesia, instrumentation, and stabilization of heart rate, MAP, and ventilation, 6 group I dogs were infused with phenylephrine until a 50% increase in MAP was recorded (phenylephrine control). On subsequent research days, each dog was anesthetized, instrumented as described, and given (IV) 1 of 3 dosages of acetylpromazine in the following order--0.05, 0.125, and 0.25 mg/kg. The dose of phenylephrine necessary to increase MAP 50% in the presence of acetylpromazine was recorded. Five group II dogs were studied as in group I, but each dog was given (IM) atropine (0.04 mg/kg) before anesthetization. Two dosages of acetylpromazine were studied in the following order--0.05 and 0.25 mg/kg. Group I dogs, when compared with their phenylephrine controls, were given significantly more phenylephrine to raise MAP 50% at each dose of acetylpromazine studied. The same trend was observed in group II dogs, but at smaller doses of phenylephrine, probably as a result of the positive chronotropic effect of atropine on the heart.
为了定量测定乙酰丙嗪诱导的α-肾上腺素能受体阻滞作用，将去氧肾上腺素注入犬体内。在给予或未给予乙酰丙嗪之前，使平均动脉血压（MAP）比基线升高50%所需的去氧肾上腺素量，用于量化乙酰丙嗪诱导的α-肾上腺素能受体阻滞程度。7只犬用硫喷妥钠麻醉，维持在氧气和氟烷中，并进行机械通气。所有输注均通过头静脉中的导管进行。连续记录MAP和II导联心电图。麻醉诱导、仪器安装以及心率、MAP和通气稳定后，给6只I组犬输注去氧肾上腺素，直至记录到MAP升高50%（去氧肾上腺素对照）。在随后的研究日，每只犬麻醉后，按上述方法安装仪器，并按以下顺序静脉注射3种剂量之一的乙酰丙嗪——0.05、0.125和0.25 mg/kg。记录在存在乙酰丙嗪的情况下使MAP升高50%所需的去氧肾上腺素剂量。5只II组犬按I组方法进行研究，但每只犬在麻醉前肌肉注射阿托品（0.04 mg/kg）。按以下顺序研究2种剂量的乙酰丙嗪——0.05和0.25 mg/kg。I组犬与它们的去氧肾上腺素对照相比，在研究的每种乙酰丙嗪剂量下，为使MAP升高50%给予的去氧肾上腺素明显更多。II组犬也观察到相同趋势，但去氧肾上腺素剂量较小，可能是由于阿托品对心脏的正性变时作用。
