title: Ca2+-cyclic AMP interaction in chemically skinned smooth muscle.
abstract: Using guinea-pig taenia coli smooth muscle that is chemically skinned with Triton X-100 to functionally destroy plasmalemma as well as sarcoplasmic reticulum, we demonstrate that cAMP can enhance the extent as well as the rate of relaxation produced by lowering free [Ca2+] in a skinned fiber bundle precontracted with maximal [Ca2+]. However, these actions of cAMP are strongly dependent on the level of free [Ca2+] in the bathing medium, the effect of cAMP being greatly attenuated at higher [Ca2+]. These data support and further extend the results of our previous study indicating that modulations in [Ca2+] can have a strong influence on the ability of cAMP to produce a direct inhibitory effect on the contractile machinery in smooth muscle.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects / Q000502:physiology; D000242:Cyclic AMP / 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
chemical_list: D000242:Cyclic AMP; D002118:Calcium