A special manifestation of the myogenic tone
is the myogenic response (also called the Bayliss effect) in the vasculature. The Bayliss effect in vascular smooth muscles
cells is a response to stretch. This is especially relevant in arterioles
of the body. When blood pressure is increased in the blood vessels and the blood vessels distend, they react with a constriction; this is the Bayliss effect. Stretch of the muscle membrane opens a stretch-activated ion channel
. The cells then become depolarized and this results in a Ca<sup>2+</sup> signal and triggers muscle contraction
. It is important to understand that no action potential is necessary here; the level of entered calcium affects the level of contraction proportionally and causes tonic contraction. The contracted state of the smooth muscle depends on the grade of stretch and plays an important part in the regulation of blood flow.
Increased contraction increases the total peripheral resistanse (TPR) and this further increases the mean arterial pressure (MAP). This is explained by the following equation:<math>MAP = CO * TPR </math>
This effect is independent of nervous mechanisms and that is how we differentiate it from the myogenic tone, which is controlled by the sympathetic nervous system
The overall effect of the myogenic response (Bayliss effect) is to decrease blood flow across a vessel after an increase in blood pressure.
The Bayliss effect
(or Bayliss myogenic response
) was... Read More