Clark A W
J Cell Biol. 1976 Jun;69(3):521-38. doi: 10.1083/jcb.69.3.521.
Neuromuscular junctions of the frog, Rana pipiens, were examined for structural modifications produced by exposure to increased and reduced osmotic pressure (pi). Preparations exposed to increased pi for varying lengths of time were fixed with either OSO4-Veronal with and without calcium, glutaraldehyde-phosphate, or glutaraldehyde-formaldehyde-phosphate as primary fixatives. The greatest difference between the fixatives was seen in preparations exposed to increased pi for 5 min, corresponding to the time when miniature endplate potential frequency is highest. The 5-min OSO4 calcium-free preparations appeared comparatively normal, while those fixed with OSO4 and 2 mM CaCl2 or aldehyde-phosphate had wide infoldings of the presynaptic membrane and a reduced number of synaptic vesicles. Aldehyde-phosphate had the same effect on mouse diaphragm. Another series of frog preparations were conditioned to elevated pi and then returned to normal Ringer's for varying times before fixation in OSO4-phosphate. Preparations fixed 2 min after their return to normal Ringer's showed marked disruption of the presynaptic membrane as well as apparently rupturing vesicles. If fixed after 10 min, terminals were depleted of vesicles although the presynaptic membrane had returned to its normal position and appearance.
对牛蛙（Rana pipiens）的神经肌肉接头进行了检查，以观察暴露于渗透压（pi）升高和降低的环境中所产生的结构变化。将暴露于pi升高环境中不同时长的标本，分别用含或不含钙的四氧化锇-巴比妥酸盐、戊二醛-磷酸盐或戊二醛-甲醛-磷酸盐作为初次固定剂进行固定。在暴露于pi升高环境5分钟的标本中，观察到固定剂之间的最大差异，这一时间点对应的是微小终板电位频率最高的时候。暴露于pi升高环境5分钟的无钙四氧化锇固定标本相对正常，而用含2 mM氯化钙的四氧化锇或醛-磷酸盐固定的标本则出现突触前膜广泛内褶，突触小泡数量减少。醛-磷酸盐对小鼠膈肌有相同的作用。另一组牛蛙标本先暴露于pi升高环境，然后在不同时间后回到正常任氏液中，之后用四氧化锇-磷酸盐进行固定。回到正常任氏液2分钟后固定的标本显示突触前膜明显破坏，小泡明显破裂。如果在10分钟后固定，尽管突触前膜已恢复到正常位置和外观，但神经末梢的小泡已耗尽。
