低钙对鲫鱼视网膜中视杆、视锥信号向水平细胞传递的不同作用
王海龙, 扬雄里
(中国科学院上海生理研究所,上海生命科学联合实验室,上海 200031
摘要
工作应用细胞内记录技术,在灌流的卿鱼离体视网膜的标本上,研究了低钙对外网状层中视锥、视杆信号向水平细胞传递的不同影响。当降低灌流溶液中C,2+浓度至0. 1 mmol/L时使视锥一和视杆一水平细胞((Cone-HC和Rod-HC)均去极化,但对两者的光反应性有不同的影响:使L型Cone-HC对680 nm和500 nm闪光反应的幅度有不同程度的减小,但使Rod-HC对光反应 的幅度显著增大。在0. 1 mmol/L Cal+ Ringer液灌流时,无论是明视PI(反映视锥活动)或暗 视PI(反映视杆活动),其反应的幅度均增大,提示发生在低钙时Cone-HC和Rod-HC光反应性的不同变化产生于突触传递的过程中。进而,磷酸二醋酶抑制剂IBMX对PI的影响与0.1 mmol/L Ca2+ Ringer液的作用相似,而对L型Cone-HC和Rod-HC的作用均是使光反应性增大。 这提示,在。. 1 mmol/L Cal+的Ringer液中,Cone-HC和Rod-HC光反应性的变化差异可能是由于低钙对视锥和视杆终末Cal十内流的不同影响而产生。
DIFFERENTIAL EFFECTS OF LOW CALCIUM ON SIGNAL TRANSMISSION FROM RODS AND CONES TO HORIZONTAL CELLS IN CARP RITINA
Wang Hailong, Yang Xiongli
(Shanghai Insititute of Physiology, Shanghai Joint Laboratory of Life Science, Chinese Academy of Seiences, Shahghai 200031)
Abstract
Intracellular recordings were made from neurons in the superfused isolated carpretina and the effects of calcium on synaptic transmission from cones and rods to horizontal cells were studied by changing the ionic composition of the external medium.When extracellular Ca2+ is lowered from 1. 2 mmol/L to 0. 1 mmol/L,both cone- and rod-horizontal cells (Cone-HC and Rod-HC) are depolarized,but light responsiveness of these cells are differentially affected:light responses of Cone-HCs are reduced in
size,whereas those of Rod-HCs are significantly enhanced. In 0. 1 mmol/L Ca2+,glutamate-isolated P 1Q components,both photopic and scotopic,are enhanced,suggesting that the differential effects of low calcium on the horizontal cells must occur during signal transferring from photoreceptors to horizontal cells. Similar to the effect of 0. 1mmol/L Caz+,phosphodiesterase inhibitor IBMX(5 0 pmol/ L) is also capable of enhancing light responsiveness of both L-type Cone-HC and Rod-HC. These results suggest that the differentail effects of low calcium on the two types of horizontal cells may
be due to different changes in the calcium influx into the receptor terminals.
Key words: retinal horizontal cen;Synaptic transmission;photoreceptor;calcium
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引用本文:
王海龙, 扬雄里. 低钙对鲫鱼视网膜中视杆、视锥信号向水平细胞传递的不同作用[J]. 生理学报 1996; 48 (2): .
Wang Hailong, Yang Xiongli. DIFFERENTIAL EFFECTS OF LOW CALCIUM ON SIGNAL TRANSMISSION FROM RODS AND CONES TO HORIZONTAL CELLS IN CARP RITINA. Acta Physiol Sin 1996; 48 (2): (in Chinese with English abstract).