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NBME 22 Answers

nbme22/Block 3/Question#37

A 35-year-old man with bronchial asthma starts ...

Increase in cAMP

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submitted by mcl(220),

Beta-2 receptors are coupled to Gs proteins, which activate adenylyl cyclase and increase cAMP. Cyclic AMP then increases activity of protein kinase A, which phosphorylates myosin light chain kinase, ultimately resulting in smooth muscle relaxation. Albuterol, a B2 agonist, is therefore useful in treating bronchospasm.

impostersyndromel1000  are you able to clarify that phosphorylated myosin light chain kinase from cAMP/PKA and dephosphorylated myosin light chain from cGMP both cause smooth muscle relaxation? saw this on another Q with the nitrates causing headache so now im confused +  
dubywow  @impostersyndromel1000: Here is an image that summarizes cAMP and cGMP actions in smooth muscle cell very will. Hope it helps. link +