Die Rolle der Erythrozytären NO Synthase in der Regulation des Gefässtonum

14/10/2022 to 31/12/2026

The endothelial nitric oxide synthase (eNOS) and the soluble guanylate cyclase (sGC) play a central role in the control of vascular tone. In the previous funding period, we found that also red blood cells carry an eNOS/sGC signaling pathway. Moreover, we created endothelial cell (EC)-specific and RBC-specific eNOS knock-out (KO)/ and knock-in (KI) mice, as well as RBC sGC KO mice by using the Cre/LoxP technology; we found that RBC eNOS KO and RBC sGC KO are hypertensive and that reactivation of eNOS in RBCs rescues conditional eNOS KO mice from hypertension. In addition, we have preliminary results indicating that the eNOS/sGC signaling controls the release of NO bioactivity via the anion exchanger-1 (AE-1). In this project, we aim to investigate whether the red cell eNOS/sGC signaling pathway regulates the export of NO bioactivity via AE-1 and thereby modulates vascular tone, blood flow, and blood pressure. Specifically, we have three main objectives: we aim to analyze (1) the effects of red cell eNOS/sGC signaling on the activity of AE-1, the export of NO bioactivity and RBC-mediated vascular responses under normoxic and hypoxic conditions ex vivo, (2) the role of red cell eNOS/sGC signaling in AngII-induced hypertension in vivo in RBC eNOS KO, RBC eNOS KI, and RBC sGC KO mice; (3) the changes of red cell eNOS/sGC signaling and release of NO bioactivity in patients with hypertension. We anticipate that lack of eNOS/sGC signaling in RBCs will decrease the export of NO metabolites and hypoxic vasodilation by RBCs ex vivo and that will exacerbate AngII-induced hypertension, as well as impairment of renal blood flow via a decreased export of eNOS-dependent NO bioactivity from the RBCs. Moreover, we expect that RBCs from hypertensive patients will show decreased RBC-derived NO bioactivity and hypoxic vasodilation. These studies will reveal the link between red cell eNOS/sGC signaling, release NO bioactivity and systemic hemodynamics or control of local blood flow. Moreover, the results of these studies will strongly contribute to our understanding of the role of RBC signaling in the control of vascular tone, blood flow, and blood pressure, revealing clinical diagnostic markers in hypertension as well as new druggable targets for pharmacological/nutritional intervention.