Cyclic GMP-dependent protein kinase relaxes skinned fibers from guinea pig taenia coli but not from chicken gizzard.
The effect of cGMP and cGMP-dependent protein kinase (cG-PK) on contraction and relaxation was studied in skinned smooth muscle fibers from guinea pig taenia coli and chicken gizzard. At a fixed [Ca2+] relaxation was significantly enhanced by activated cG-PK in fibers from guinea pig taenia coli, but not in those from chicken gizzard. The Ca2+-requirement for half maximal tension maintenance was shifted to the right. Relaxation was associated with a decline in phosphorylated myosin light chain-2 from 34% to 25%. Similarly to relaxation activated cG-PK inhibited tension development only in fibers from taenia coli. These results suggest that mammalian and chicken smooth muscle fibers respond differently to cG-PK.
D000818:Animals; D002645:Chickens; D006152:Cyclic GMP / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009218:Myosins / Q000378:metabolism; D011494:Protein Kinases / Q000494:pharmacology*
D011494:Protein Kinases; D009218:Myosins; D006152:Cyclic GMP