EDNRA and subarachnoid hemorrhage: It has therefore been suggested that released hemoglobin plays a significant role in the formation of vasospasm and pericyte cell death via nitric oxide scavenging and the endothelin-1 system in subarachnoid hemorrhage, which is why a large series of clinical trials (CONSCIOUS-1, CONSCIOUS-2, CONSCIOUS-3, REACT) investigated the impact of the endothelin-1 receptor antagonist clozasentan on vasospasm and clinical outcomes in these patients [37,38,39,40].