Dearworth J R, Cooper L J, McGee C
Department of Biology, 311 Kunkel Hall, Lafayette College, Easton, PA 18042, USA.
Vet Ophthalmol. 2007 Mar-Apr;10(2):106-10. doi: 10.1111/j.1463-5224.2007.00518.x.
We investigated effects of both vecuronium bromide, a nicotinic cholinergic antagonist, and atropine, a muscarinic cholinergic antagonist, on the pupil of the turtle to determine whether responses to light are controlled by parasympathetic innervations acting on the iris.
Three red-eared slider turtles, Pseudemys scripta elegans.
Turtles were secured to immobilize their head movements and then inserted into a light-integrating sphere. Both pupils were monitored through small apertures by digital video cameras. Pupil diameters were measured manually with a digital caliper. During each trial, drugs (0.4%) were topically applied, four times at 15 min intervals, to the corneas of each eye. One eye was randomly selected for treatment of the drug while the other, treated with saline (0.9% NaCl), was used as control. Pupil sizes under adaptation to light were tracked after drug or saline applications.
Mean pupillary diameters of eyes treated with vercuronium bromide increased by 28%, reaching peak size in 90 min. Onset of response occurred 20 min after drug application and then increased at a rate having a time constant of 26 min. Recovery began at 120 min after initial application. Atropine had no effect on pupil size. No systemic side effects by drugs were observed in turtles.
Although atropine does not cause mydriasis, vecuronium bromide does. These results suggest that the parasympathetic system in turtles acts through acetylcholine onto nicotinic receptors to stimulate pupillary light constriction.
我们研究了烟碱型胆碱能拮抗剂维库溴铵和毒蕈碱型胆碱能拮抗剂阿托品对乌龟瞳孔的影响，以确定对光的反应是否由作用于虹膜的副交感神经支配控制。
三只红耳滑龟，即锦龟指名亚种。
将乌龟固定以使其头部不能移动，然后放入一个光积分球中。通过小孔用数字摄像机监测双侧瞳孔。用数字卡尺手动测量瞳孔直径。在每次试验中，将药物（0.4%）以15分钟的间隔分四次局部应用于每只眼睛的角膜。随机选择一只眼睛用药物治疗，另一只眼睛用生理盐水（0.9%氯化钠）治疗作为对照。在应用药物或生理盐水后，追踪适应光线时的瞳孔大小。
用维库溴铵治疗的眼睛的平均瞳孔直径增加了28%，在90分钟时达到最大尺寸。给药后20分钟出现反应，然后以时间常数为26分钟的速率增加。在首次给药后120分钟开始恢复。阿托品对瞳孔大小没有影响。在乌龟身上未观察到药物的全身副作用。
虽然阿托品不会引起瞳孔散大，但维库溴铵会。这些结果表明，乌龟的副交感神经系统通过乙酰胆碱作用于烟碱受体来刺激瞳孔对光收缩。
