title: Inhibition of smooth muscle tension by cyclic AMP-dependent protein kinase.
abstract: beta-Adrenergic relaxation of smooth muscle by catecholamines has been associated with elevated levels of cyclic AMP. The question arises whether subsequent activation of cyclic AMP-dependent protein kinase has a role in the regulation of smooth muscle contraction. There is substantial evidence that a Ca2+-activated myosin light chain kinase/phosphatase system regulates smooth muscle contraction, and Adelstein et al. have shown that the catalytic subunit of cyclic AMP-dependent protein kinase plays a part in this regulation, by phosphorylation of the high molecular weight subunit of the light chain kinase, which results in a decrease in the activity of the kinase. Here we have shown for the first time that the catalytic subunit of the protein kinase inhibits Ca2+-activated tension in skinned smooth muscle fiber preparations.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D002645:Chickens; D000242:Cyclic AMP / Q000502:physiology; D005895:Gizzard, Avian / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000502:physiology*; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000502:physiology*
chemical_list: D002147:Calmodulin; D047428:Protein Kinase Inhibitors; D000242:Cyclic AMP; D011494:Protein Kinases; D009218:Myosins; D002118:Calcium