Kuriyama S, Yoshimura N, Ohuchi T, Tanihara H, Ito S, Honda Y
Department of Ophthalmology, Kyoto University Faculty of Medicine, Japan.
Brain Res. 1992 May 8;579(2):227-33. doi: 10.1016/0006-8993(92)90055-e.
Neuropeptide-induced mobilization of cytosolic free Ca2+ concentration ([Ca2+]i) and phosphatidylinositol (PI) turnover in cultured human retinal pigment epithelial (RPE) cells were studied and their temporal relationship was compared. After RPE cells were loaded with fura-2/AM, [Ca2+]i was analyzed using a digital imaging microscopy system. Bombesin-related peptides which include bombesin, neuromedin B, and neuromedin C induced significant [Ca2+]i transients in RPE cells, whereas other neuropeptides, neuropeptide Y, vasoactive intestinal polypeptide (VIP), and substance P were not effective to produce [Ca2+]i transients. The percentage of reactive cells which showed positive [Ca2+]i transients induced by bombesin-related peptides was around 50%. Bombesin (1 microM) showed a peak concentration of 663 +/- 27.0 nM (mean +/- S.E.M., n = 61), neuromedin B (1 microM), 327 +/- 28.7 nM (mean +/- S.E.M., n = 38), and neuromedin C (1 microM), 357 +/- 22.7 nM (mean +/- S.E.M., n = 32). Ca2+ transients occurred within 30 s and lasted less than 5 min after the application of the neuropeptides. Chelation of the extracellular Ca2+ by EGTA significantly shortened the total time of [Ca2+]i transients induced by the above. The measurements of phosphoinositides in RPE cells revealed that neuropeptide-induced PI turnover was as quick as [Ca2+]i transients. Inositol biphosphate (IP2) and inositol triphosphate (IP3) in RPE cells showed transient increases at 15 s after the stimulation by bombesin-related peptides. These data show that changes in [Ca2+]i and PI turnover are directly linked and both are important in the signal transduction system of bombesin-related peptides in RPE cells. The data also suggest that bombesin-related peptides may play some possible roles in RPE cells.
研究了神经肽诱导的培养人视网膜色素上皮（RPE）细胞胞质游离钙离子浓度（[Ca2+]i）的动员和磷脂酰肌醇（PI）周转，并比较了它们的时间关系。用fura-2/AM加载RPE细胞后，使用数字成像显微镜系统分析[Ca2+]i。包括蛙皮素、神经降压素B和神经降压素C在内的蛙皮素相关肽在RPE细胞中诱导了显著的[Ca2+]i瞬变，而其他神经肽，如神经肽Y、血管活性肠肽（VIP）和P物质则不能有效产生[Ca2+]i瞬变。显示由蛙皮素相关肽诱导的阳性[Ca2+]i瞬变的反应性细胞百分比约为50%。蛙皮素（1μM）显示峰值浓度为663±27.0 nM（平均值±标准误，n = 61），神经降压素B（1μM）为327±28.7 nM（平均值±标准误，n = 38），神经降压素C（1μM）为357±22.7 nM（平均值±标准误，n = 32）。施加神经肽后，Ca2+瞬变在30秒内发生，持续时间不到5分钟。EGTA对细胞外Ca2+的螯合显著缩短了上述诱导的[Ca2+]i瞬变的总时间。RPE细胞中磷酸肌醇的测量显示，神经肽诱导的PI周转与[Ca2+]i瞬变一样快。RPE细胞中的肌醇二磷酸（IP2）和肌醇三磷酸（IP3）在蛙皮素相关肽刺激后15秒出现瞬时增加。这些数据表明，[Ca2+]i和PI周转的变化直接相关，并且两者在RPE细胞中蛙皮素相关肽的信号转导系统中都很重要。数据还表明，蛙皮素相关肽可能在RPE细胞中发挥一些可能的作用。
