Protein kinase A activity and NO are involved in the regulation of crucian carp (Carassius carassius) red blood cell osmotic fragility.

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.