Abstract
BackgroundNitric oxide (NO) produced by nitric oxide synthase (NOS) in human red blood cells (RBCs) was shown to depend on shear stress and to exhibit important biological functions, such as inhibition of platelet activation. In the present study we hypothesized that exercise-induced shear stress stimulates RBC-NOS activation pathways, NO signaling, and deformability of human RBCs.Methods/FindingsFifteen male subjects conducted an exercise test with venous blood sampling before and after running on a treadmill for 1 hour. Immunohistochemical staining as well as western blot analysis were used to determine phosphorylation and thus activation of Akt kinase and RBC-NOS as well as accumulation of cyclic guanylyl monophosphate (cGMP) induced by the intervention. The data revealed that activation of NO upstream located enzyme Akt kinase was significantly increased after the test. Phosphorylation of RBC-NOSSer1177 was also significantly increased after exercise, indicating activation of RBC-NOS through Akt kinase. Total detectable RBC-NOS content and phosphorylation of RBC-NOSThr495 were not affected by the intervention. NO production by RBCs, determined by DAF fluorometry, and RBC deformability, measured via laser-assisted-optical-rotational red cell analyzer, were also significantly increased after the exercise test. The content of the NO downstream signaling molecule cGMP increased after the test. Pharmacological inhibition of phosphatidylinositol 3 (PI3)-kinase/Akt kinase pathway led to a decrease in RBC-NOS activation, NO production and RBC deformability.Conclusion/SignificanceThis human in vivo study first-time provides strong evidence that exercise-induced shear stress stimuli activate RBC-NOS via the PI3-kinase/Akt kinase pathway. Actively RBC-NOS-produced NO in human RBCs is critical to maintain RBC deformability. Our data gain insights into human RBC-NOS regulation by exercise and, therefore, will stimulate new therapeutic exercise-based approaches for patients with microvascular disorders.
Highlights
Nitric oxide (NO), a highly reactive and short-lived diffusible molecule regulates central physiological mechanisms, e.g. vascular tone, macrophage-mediated neurotoxicity, anti-apoptotic activity [1], or mitogen-activated protein (MAP) kinase signaling [2]
Immunohistochemical straining was performed Pre and Post acute moderate running test (AMRT) to investigate whether moderate exercise influences red blood cell NOS (RBCNOS) activation pathway
NO generation and –mediated signaling are highly important for the regulation of the peripheral vascular bed [28,29] and NO produced by endothelial NOS (eNOS) in endothelial cells plays a prominent role in these regulations
Summary
Nitric oxide (NO), a highly reactive and short-lived diffusible molecule regulates central physiological mechanisms, e.g. vascular tone, macrophage-mediated neurotoxicity, anti-apoptotic activity [1], or mitogen-activated protein (MAP) kinase signaling [2]. Recent in vitro examinations have shown that the application of continuous shear stress activates RBC-NOS and NO production [10]. This leads to the indication of important influences of mechanical stimulations in the vascular bed on RBC-NOS activation and subsequent NO formation to maintain RBCs deformability and, peripheral oxygen supply. Nitric oxide (NO) produced by nitric oxide synthase (NOS) in human red blood cells (RBCs) was shown to depend on shear stress and to exhibit important biological functions, such as inhibition of platelet activation. In the present study we hypothesized that exercise-induced shear stress stimulates RBC-NOS activation pathways, NO signaling, and deformability of human RBCs
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