Second, renin–angiotensin system activation in peripheral blood vessels has been shown to increase the production of endogenous vasoconstrictor endothelin I via angiotensin I and angiotensin II receptor–mediated activation of nuclear transcription factor‐kb.38–39 In kidney transplant recipients treated with cyclosporine, nitric oxide levels are reduced and endothelium‐dependent vasodilatation is impaired.40 Amore et al41 in their animal study showed that cyclosporine‐mediated vasoconstriction can be prevented by administration of l‐arginine (increasing nitric oxide). Here, REN is linked to medical procedure.