Calderone L, Grimes P, Shalev M
Exp Eye Res. 1986 Apr;42(4):331-7. doi: 10.1016/0014-4835(86)90026-6.
Combined administration of ketamine and xylazine is used increasingly for safe, effective anesthesia of small laboratory animals. We found that rats injected systemically with ketamine and xylazine at doses recommended for effective anesthesia developed acute reversible lens opacities. Mice given the same drug doses were similarly affected. Testing of each drug alone demonstrated that xylazine was the causative agent. The appearance of cataract was associated to varying degree with proptosis, suppression of the blink reflex, corneal surface drying, and mydriasis. All of these ocular effects, including cataract also could be induced locally by topical application of xylazine to one eye, with untreated contralateral eyes showing no drug effects. A possible cause of xylazine-induced transient lens opacification is trans-corneal water loss and alteration of aqueous humor composition due to corneal exposure. Additional action on aqueous humor formation and the lens itself may be due to the alpha-2-adrenoceptor nature of xylazine. Whatever the cause of cataract induction, the occurrence of this phenomenon during ketamine-xylazine anesthesia appears to be associated with marked changes in the physiological state of the eye. Therefore, the side-effects of anesthetic drug combination should be considered prior to its use on animals for studies of ocular physiology.
氯胺酮和赛拉嗪联合给药越来越多地用于小型实验动物的安全、有效麻醉。我们发现，按有效麻醉推荐剂量全身注射氯胺酮和赛拉嗪的大鼠出现了急性可逆性晶状体混浊。给予相同药物剂量的小鼠也受到类似影响。单独对每种药物进行测试表明，赛拉嗪是致病因素。白内障的出现与不同程度的眼球突出、眨眼反射抑制、角膜表面干燥和瞳孔散大有关。所有这些眼部效应，包括白内障，也可以通过将赛拉嗪局部应用于一只眼睛而局部诱发，未治疗的对侧眼睛未显示药物效应。赛拉嗪诱导短暂性晶状体混浊的一个可能原因是角膜暴露导致的经角膜水分流失和房水成分改变。对房水形成和晶状体本身的额外作用可能归因于赛拉嗪的α-2-肾上腺素能受体性质。无论白内障诱导的原因是什么，氯胺酮-赛拉嗪麻醉期间这种现象的发生似乎与眼睛生理状态的明显变化有关。因此，在将麻醉药物组合用于动物进行眼生理学研究之前，应考虑其副作用。
