SLC9C1 and deep vein thrombosis: Serum Angiotensin II levels are increased with ACE2 blocking by COVID-19. Angiotensin II stimulation and local stimuli such as H+ ion and hypoxia activate Na+/H+ exchanger (NHE) in both vascular endothelium and platelets. COVID-19 can lead to thrombosis by causing NHE activation.