EDN1 and ischemia: The lack of reflow is largely due to pericyte capillary constriction during and after ischemia (6, 18), possibly as a result of the cytoplasmic Ca2+ concentration ([Ca2+]i) rising in pericytes after a fall of ATP level ([ATP]i) inhibits ion pumping; however, release of vasoconstrictors, such as endothelin-1 (ET-1) and thromboxane, in ischemic stroke may also contribute (19–21).