REN and hypertensive disorder: Animal studies have also shown that acute and chronic lead exposure cause hypertension and cardiovascular disease by altering the renin-angiotensin-aldosterone system: increasing angiotensin-converting enzyme activity [2, 8, 9], inhibiting Na+-K+-ATPase [10], inducing oxidative stress, reducing nitric oxide bioavailability, [11, 12] and depleting antioxidant reserves [13].