Baxter G M, Tackett R L, Moore J N
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602.
Vet Surg. 1989 May-Jun;18(3):221-6. doi: 10.1111/j.1532-950x.1989.tb01075.x.
Palmar digital arteries and veins removed surgically from healthy horses under general anesthesia were cut into 4 mm vascular rings, suspended in tissue baths, and attached to force displacement transducers for continuous measurement of vascular tension. In vitro vascular responses were determined for acetylcholine, acepromazine, isoxsuprine hydrochloride (isoxsuprine), prostaglandin E2 (PGE2), and prostaglandin I2 (prostacyclin). After preconstriction with norepinephrine hydrochloride (norepinephrine), or prostaglandin F2 alpha (PGF2 alpha), the concentrations needed to produce 50% maximum relaxation (EC50) and the maximum percentage of relaxation were determined for each drug. Acetylcholine was the most potent arterial vasodilator (smallest EC50 value) and PGE2 was the least potent. Prostacyclin was the least potent venodilator (highest EC50 value); there were no differences between acetylcholine, acepromazine, isoxsuprine, and PGE2. Isoxsuprine produced greater arterial relaxation than all other agents. Isoxsuprine and acepromazine produced significantly greater venous relaxation than did acetylcholine and PGE2. Prostacyclin produced minimal vasodilation of arteries or veins. Acepromazine and isoxsuprine relaxed the veins significantly more than the arteries. When PGF2 alpha was used instead of norepinephrine to preconstrict the arteries and veins, the potency and effectiveness of acepromazine and isoxsuprine to produce vasodilation were significantly decreased. Results indicate that acepromazine and isoxsuprine can relax the equine digital vasculature but their effectiveness varies depending on the origin of the constriction.
在全身麻醉下从健康马匹身上手术切除的掌侧指动脉和静脉被切成4毫米的血管环，悬挂在组织浴中，并连接到力位移传感器上以连续测量血管张力。测定了乙酰胆碱、乙酰丙嗪、盐酸异克舒令（异克舒令）、前列腺素E2（PGE2）和前列腺素I2（前列环素）的体外血管反应。在用盐酸去甲肾上腺素（去甲肾上腺素）或前列腺素F2α（PGF2α）预收缩后，确定每种药物产生最大舒张50%所需的浓度（EC50）和最大舒张百分比。乙酰胆碱是最有效的动脉血管扩张剂（EC50值最小），而PGE2的效力最低。前列环素是效力最低的静脉扩张剂（EC50值最高）；乙酰胆碱、乙酰丙嗪、异克舒令和PGE2之间没有差异。异克舒令比所有其他药物产生更大的动脉舒张。异克舒令和乙酰丙嗪产生的静脉舒张明显大于乙酰胆碱和PGE2。前列环素对动脉或静脉产生的血管扩张最小。乙酰丙嗪和异克舒令使静脉舒张明显大于动脉。当使用PGF2α代替去甲肾上腺素对动脉和静脉进行预收缩时，乙酰丙嗪和异克舒令产生血管扩张的效力和效果显著降低。结果表明，乙酰丙嗪和异克舒令可以使马的指部血管舒张，但其效果因收缩的来源而异。
