Modulation of gap junctions between retinal neurons by intracellular messengers.

细胞内注射环鸟苷酸或可溶性鸟苷酸环化酶激活剂，如一氧化氮（NO）和花生四烯酸，关闭水平细胞之间的间隙连接在鲤鱼（鲤鱼）和海龟（龟）视网膜。为了确定环鸟苷酸对差距连接的阻断作用是否是通过环鸟苷酸依赖的蛋白激酶的作用，我们通过向鲤鱼视网膜发光型水平（H1）细胞中注射蛋白激酶抑制剂来检测与荧光黄CH的染料偶联状态。在细胞内注射环GMP和环GMP-和环AMP-依赖性蛋白激酶A-3（N-（2-氨乙基）-5-氯萘-1-磺酰胺盐酸盐）的混合物后，观察到水平细胞之间的染料偶联。在水平细胞内注射环GMP和环GMP依赖性蛋白激酶抑制肽（Arg-Lys-Arg-Ala-Arg-Lys-Glu）的混合物后，也观察到染料偶联，表明该抑制剂抑制了环GMP的去偶联作用，而该激酶抑制剂不抑制环AMP对差距连接的去偶联作用。另一方面，在注射环GMP和环AMP依赖性蛋白激酶抑制剂肽（Arg-Gly-Try-Ala-Leu-Gly）的混合物后，观察到单个细胞发荧光。这些结果表明，环GMP对水平细胞之间的间隙连接细胞间通讯的阻断作用是通过环GMP依赖性蛋白激酶的作用，并且环GMP以一种独立于水平细胞中众所周知的多巴胺/环AMP途径的方式调节差距连接。

Intracellular injection of cyclic GMP or soluble guanylate cyclase activators, such as nitric oxide (NO) and arachidonic acid, closed gap junctions between horizontal cells in carp (Cyprinus carpio) and turtle (Geoclemys reevesii) retinas. To determine whether the blocking effect of cyclic GMP on the gap junctions was through the action of cyclic GMP-dependent protein kinase, we examined the status of dye-coupling with Lucifer yellow CH among luminosity-type horizontal (H1) cells in the carp retina, by injection of protein kinase inhibitors into the cells. Dye-coupling among horizontal cells was observed after the intracellular injection of the mixture of cyclic GMP and a cyclic GMP-and cyclic AMP-dependent protein kinase, A-3 (N-(2-aminoethyl)-5-chloronaphthalene-1-sulfonamide hydrochloride). Dye-coupling was observed also after the injection of the mixture of cyclic GMP and cyclic GMP-dependent protein kinase inhibitor peptide (Arg-Lys-Arg-Ala-Arg-Lys-Glu) into the horizontal cell, indicating that the inhibitor suppressed the decoupling effect of cyclic GMP.The same kinase inhibitor did not suppress the decoupling effect of cyclic AMP on the gap junctions. On the other hand, a single cell was seen fluorescing after the injection of the mixture of cyclic GMP and cyclic AMP-dependent protein kinase inhibitor peptide (Arg-Gly-Try-Ala-Leu-Gly). These findings suggest that the blocking effct of cyclic GMP on gap-junctional intercellular communication among horizontal cells is through the action of cyclic GMP-dependent protein kinase, and that cyclic GMP modulates the gap junctions in a manner independent of the well-known dopamine/cyclic AMP pathway in the horizontal cell.