Hi, thanks for the video! I am a little confused because I have been reading and learning about the effects of theophylline on bronchioles. From my understanding, it is a phosphodiesterase inhibitor, thus leading to an increase in cAMP concentration in smooth muscle. I have also read that cAMP inhibits myosin light chain kinase thus causing bronchodilation/ SM relaxation. I am confused because now it seems contradictory if cAMP is shown here to induce release of calcium ion from SR. Please can you help?
You are right , from what I know cAMP cause smooth muscle relaxation by the mechanism you just mentioned , while cGMP cause relaxation by activating myosine light chain phosphatase ( through the action of protein kinase G) . Epinephrine cause smooth muscle contraction through its action on alpha 1 receptor ( Gq ) while it can cause smooth muscle relaxation through B2 ( Gs - cAMP) .. so I'm as confused as you .
I think there is a mistake with epinephrine, it works on Gq which in turn activates Phospholipase C(PLC) which then hydrolyses PIP2 giving DAG and IP3..IP3 induces the release of Ca+ etc.
this is the best video ive ever watched on this; thank you so so much!!
very helpful and just at the right level of detail, commenting to help the yt algorithms
Discovered your channel recently! Amazing indeed!
Hi, thanks for the video! I am a little confused because I have been reading and learning about the effects of theophylline on bronchioles. From my understanding, it is a phosphodiesterase inhibitor, thus leading to an increase in cAMP concentration in smooth muscle. I have also read that cAMP inhibits myosin light chain kinase thus causing bronchodilation/ SM relaxation. I am confused because now it seems contradictory if cAMP is shown here to induce release of calcium ion from SR. Please can you help?
You are right , from what I know cAMP cause smooth muscle relaxation by the mechanism you just mentioned , while cGMP cause relaxation by activating myosine light chain phosphatase ( through the action of protein kinase G) .
Epinephrine cause smooth muscle contraction through its action on alpha 1 receptor ( Gq ) while it can cause smooth muscle relaxation through B2 ( Gs - cAMP) .. so I'm as confused as you .
Thank you, sir
Thank you so much, amazing explanation!!!
How good you explained I couldn't expess!!!!!!!!!
how does the actin myosin light chain get unphosphorylated what reverses it?
Finally got someone who made this understandable 😂
Hmmm -
- cAMP (via NE/Epi, beta 2, Gs)-> smooth muscle relaxation.
- IP3 (via NE/Epi, alpha 1, Gq)-> smooth muscle contraction.
- inhibition of cAMP (via NE/Epi, alpha 2, Gi)-> smooth muscle relaxation.
Very helpful!! Thanks
so helpful thank you !!
You're very welcome!
Thanks bro....
I think there is a mistake with epinephrine, it works on Gq which in turn activates Phospholipase C(PLC) which then hydrolyses PIP2 giving DAG and IP3..IP3 induces the release of Ca+ etc.
tyyyyy