According to myogenic hypothesis of renal autoregulation, the afferent aerioles contract in response to stretch induced by

Most vascular beds have an intrinsic capacity to compensate for moderate changes in perfusion pressure by changes in vascular resistance, so that blood flow remains relatively constant. This capacity is well developed in the kidneys (), but it has also been observed in the mesentery, skeletal muscle, brain, liver, and myocardium. It is probably due in pa to the intrinsic contractile response of smooth muscle to stretch (myogenic theory of autoregulation). As the pressure rises, the blood vessels are distended and the vascular smooth muscle fibers that surround the vessels contract. If it is postulated that the muscle responds to the tension in the vessel wall, this theory could explain the greater degree of contraction at higher pressures; the wall tension is propoional to the distending pressure times the radius of the vessel (law of Laplace; see Chapter 32), and the maintenance of a given wall tension as the pressure rises would require a decrease in radius. Ref: Ganong&;s review of medical physiology,23rd edition, page: 563