Studies on the electrolyte transport in corneal cells.

角膜的透明度对于维持良好的视觉功能是非常重要的。角膜上皮细胞和内皮细胞的正常功能状态对角膜透明度至关重要。本研究研究了内皮素诱导的兔角膜上皮细胞有丝分裂和第二信使系统的作用。我们清楚地证明了以下几点：1)培养的兔角膜内皮细胞产生内皮素。通过逆转录引发的聚合酶链反应发现内皮素前体mRNA的存在。兔角膜上皮细胞培养上清中发现有放射性的内皮素。2)内皮素剂量依赖性地促进培养兔角膜上皮细胞有丝分裂发生。内皮素1剂量依赖性地增加（EC50 = 0.3 nM）细胞3h -胸苷的摄取，达到对照的200%。内皮素是一种有丝分裂原，因为低浓度胎牛血清的共存增加了有丝分裂的作用。3)内皮素增加细胞内胞浆Ca^<2+>浓度。内皮素在100 nM时使胞质游离Ca^<2+>浓度升高超过200 nM。这一现象之前是PI的更替。

The transparency of the cornea is very important for the maintenance of good visual function. Normal functional state of corneal epithelial cells as well as endothelial cells are important for the corneal transparency. In this study we have investigated endothelin-induced mitogenesis and the second messenger systems working in cultured rabbit corneal epithelial cells.We have clearly demonstrated the following :1) Cultured rabbit corneal endothelial cells produce endothelin. The occurrence of mRNA for prepro-endothelin was found by reverse transcription initiated polymerase chain reaction. In the culture supernatant of the rabbit corneal epithelial cells, radioreactive endothelin was found.2) Endothelin dose-dependently increases mitogenesis of cultured rabbit corneal epithelial cells. Endothelin 1 dose-dependently increased (EC50 = 0.3 nM) 3H-thymidine uptake of the cell up to 200% of the control. Endothelin was shown to be a comitogen because coexistence of low concentration of fetal bovine serum increased the mitogenic effect.3) Endothelin increases intracellular cytosolic Ca^<2+> concentration in the cell. Endothelin, at 100 nM, increased cytosolic free Ca^<2+> concentration by more than 200 nM. This phenomenon was preceded by PI turnover.