Inada H, Shindo H, Tawata M, Onaya T
Third Department of Internal Medicine, Yamanashi Medical University, Tamaho, Japan.
Diabetologia. 1998 Dec;41(12):1451-8. doi: 10.1007/s001250051091.
We investigated the relation between cyclic AMP (cAMP) and nitric oxide (NO) production, as well as the effect of NO on Na , K+-ATPase activity in the human neuroblastoma cell line SH-SY5Y. Two cAMP agonists, dibutyryl cAMP (DBC) and beraprost sodium (BPS), increased cAMP accumulation and NO production in a time and dose dependent manner at 50 mmol/l glucose. On the other hand, cellular sorbitol and myo-inositol contents and protein kinase C activity were not altered by DBC or BPS. A specific protein kinase A inhibitor, H-89, suppressed increases in nitrite/nitrate and cyclic GMP (cGMP) and protein kinase A activity stimulated by DBC or BPS. This finding suggests that cAMP stimulates NO production by activating protein kinase A via a pathway different from the sorbitol-myo-inositol-protein kinase C pathway. We observed that an NO donor, sodium nitroprusside, and an NO agonist, L-arginine, enhanced ouabain sensitive Na+, K+-ATPase activity at 50 mmol/l glucose. We also found that a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), inhibited Na+, K+-ATPase activity at 5 mmol/l glucose, and partially suppressed the enzyme activity stimulated by DBC or BPS. The results of this study suggest that cAMP regulates protein kinase A activity, NO production and ouabain sensitive Na+, K+-ATPase activity in a cascade fashion. The results also suggest that protein kinase A at least partially regulates Na+, K+-ATPase activity without mediation by NO in SH-SY5Y cells. We speculate that cAMP and NO are two important regulatory factors in the pathogenesis of diabetic neuropathy.
我们研究了环磷酸腺苷（cAMP）与一氧化氮（NO）生成之间的关系，以及NO对人神经母细胞瘤细胞系SH-SY5Y中钠钾ATP酶活性的影响。两种cAMP激动剂，二丁酰环磷腺苷（DBC）和贝前列素钠（BPS），在50 mmol/l葡萄糖条件下，以时间和剂量依赖的方式增加了cAMP的积累和NO的生成。另一方面，DBC或BPS并未改变细胞中山梨醇和肌醇的含量以及蛋白激酶C的活性。一种特异性蛋白激酶A抑制剂H-89，抑制了由DBC或BPS刺激引起的亚硝酸盐/硝酸盐、环磷酸鸟苷（cGMP）和蛋白激酶A活性的增加。这一发现表明，cAMP通过一条不同于山梨醇-肌醇-蛋白激酶C途径的通路激活蛋白激酶A，从而刺激NO的生成。我们观察到，一种NO供体硝普钠和一种NO激动剂L-精氨酸，在50 mmol/l葡萄糖条件下增强了哇巴因敏感的钠钾ATP酶活性。我们还发现，一种一氧化氮合酶抑制剂N-硝基-L-精氨酸甲酯（L-NAME），在5 mmol/l葡萄糖条件下抑制了钠钾ATP酶活性，并部分抑制了由DBC或BPS刺激的该酶活性。本研究结果表明，cAMP以级联方式调节蛋白激酶A活性、NO生成和哇巴因敏感的钠钾ATP酶活性。结果还表明，在SH-SY5Y细胞中，蛋白激酶A至少部分调节钠钾ATP酶活性，而无需NO的介导。我们推测，cAMP和NO是糖尿病性神经病变发病机制中的两个重要调节因子。
