Activation of the cAMP pathway by β-adrenergic stimulation and cGMP pathway by activation of guanylate cyclase substantially affects red blood cell (RBC) membrane properties in mammals. However, whether similar mechanisms are involved in RBC regulation of lower vertebrates, especially teleosts, is not elucidated yet. In this study, we evaluated the effects of adenylate cyclase activation by epinephrine and forskolin, guanylate cyclase activation by sodium nitroprusside, and the role of Na⁺/H⁺-exchanger in the changes of osmotic fragility and regulatory volume decrease (RVD) response in crucian carp RBCs. Western blot analysis of protein kinase A and protein kinase G substrate phosphorylation revealed that changes in osmotic fragility were regulated via the protein kinase A, but not protein kinase G signaling pathway. At the same time, the RVD response in crucian carp RBCs was not affected either by activation of adenylate or guanylate cyclase. Adenylate cyclase/protein kinase A activation significantly decreased RBC osmotic fragility, i.e., increased cell rigidity. Inhibition of Na⁺/H⁺-exchanger by amiloride had no effect on the epinephrine-mediated decrease of RBC osmotic fragility. NO donor SNP did not activate guanylate cyclase, however affected RBCs osmotic fragility by protein kinase G-independent mechanisms. Taken together, our data demonstrated that the cAMP/PKA signaling pathway and NO are involved in the regulation of crucian carp RBC osmotic fragility, but not in RVD response. The authors confirm that the study has no clinical trial.

通过 β-肾上腺素能刺激激活 cAMP 通路和通过激活鸟苷酸环化酶激活 cGMP 通路显着影响哺乳动物的红细胞 (RBC) 膜特性。然而，类似的机制是否涉及低等脊椎动物，尤其是硬骨鱼类的红细胞调节，尚未阐明。在本研究中，我们评估了肾上腺素和毛喉素对腺苷酸环化酶激活的影响、硝普钠对鸟苷酸环化酶的激活作用以及 Na ⁺ /H ⁺的作用。- 鲫鱼红细胞渗透脆性变化和调节体积减少 (RVD) 反应的交换剂。蛋白激酶 A 和蛋白激酶 G 底物磷酸化的蛋白质印迹分析显示渗透脆性的变化是通过蛋白激酶 A 调节的，但不是蛋白激酶 G 信号通路。同时，鲫鱼红细胞的 RVD 反应不受腺苷酸或鸟苷酸环化酶激活的影响。腺苷酸环化酶/蛋白激酶 A 激活显着降低红细胞渗透脆性，即增加细胞刚性。Na ⁺ /H ^{+ 的}抑制阿米洛利的β-交换剂对肾上腺素介导的红细胞渗透脆性降低没有影响。NO 供体 SNP 不激活鸟苷酸环化酶，但通过不依赖蛋白激酶 G 的机制影响红细胞渗透脆性。总之，我们的数据表明 cAMP/PKA 信号通路和 NO 参与了鲫鱼红细胞渗透脆性的调节，但不参与 RVD 反应。作者确认该研究没有临床试验。