Question

you notice that after flushing the organ bath the vascular tissue contracts. You suspect that could be a response to stretch and check your hypothesis by stretching the tissue and find it does contract in response to stretch. Using verapamil stops the stretch induced contractions in this tissue. Explain how stretch of vascular smooth muscle can produce contraction that depends on L-type channels even though it is known the L-type channel cannot be activated by stretch, include the name of at least 1 stretch gated channel found in smooth muscle in your answer.

Answer 1

Initiation of smooth muscle contraction is governed by thick filaments upon Ca2+-mediated changes whereas the same changes in thin muscles play role in striated muscle contraction. Upon activated by stimuli, there will be a increase in intercellular calcium ion concentration together work with the acidic protein calmodulin.

Smooth muscle cell contraction is principally regulated by the receptors, the mechanical activation or stretching of contractile proteins also take part. Though the muscle contraction is primarily triggered by firing of an action potential, the activation of stretch dependant ion channels especially L-type channels also play role in triggering contraction. Example: L-type Ca2+ channelsin the smooth muscle cell triggers muscle contraction by initiation of vascular smooth muscle cell stretching.