Myogenic Mechanisms Regulating Blood Flow
Myogenic mechanisms are intrinsic to the smooth muscle blood vessels, particularly in small arteries and arterioles. If the pressure within a vessel is suddenly increased, the vessel responds by constricting. Diminishing pressure within the vessel causes relaxation and vasodilation. This response is observed in vivo and in isolated, pressurized blood vessels.
The myogenic mechanism may play a role in autoregulation of blood flow and in reactive hyperemia. Myogenic behavior has not been clearly identified in all vascular beds, but it has been noted in the splanchnic and renal circulations, and may be present to a small degree in skeletal muscle.
Electrophysiological studies have shown that vascular smooth muscle cells depolarize when stretched, leading to contraction. Stretching also increases the rate of smooth muscle pacemaker cells that spontaneously undergo depolarization and repolarization.
RK Revised 04/06/2007