For the same arterial blood pressure, each organ gets different blood flow due to difference in the resistance of that organ's arterioles.
By reducing the MAP, we will get different change in the blood flow to different organs, e.g the kidneys have significant drop in blood flow compared to the liver for the same level of blood pressure drop this because the kidney has a low resistance compared to the liver which has high resistance, that is why the kidneys are affected significantly at any drop in the blood pressure compared to the liver which requires deeper drop in the blood pressure (it is common to see ATN due to hypotension compared to shocked liver).
