Whenever availability of oxygen to tissues decreases immediately
Vasodilator Theory for Acute Local Blood Flow Regulation Possible Special Role of Adenosine. According to this theory, the greater the rate of metabolism or the less the availability of oxygen or some other nutrients to a tissue, the greater the rate of formation of vasodilator substances in the tissue cellsRef: Guyton 11th edition pg no: 196
Vasodilation and increase in blood supply to tissue takes place
Vasoconstriction and decreases in blood supply to tissue takes place
Venoconstriction and increase in tissue perfusion pressure occurs
Venodilation and decrease in tissue perfusion pressure occur
Endocrinology