The effect of atrial natriuretic peptide (ANP) on angiotensin II- and histamine-induced contraction and muscle light chain phosphorylation was examined in strips of rabbit aorta smooth muscle. Preincubation of strips with 10-7 M ANP prior to addition of either agonist inhibits both the increase in extent of myosin light chain phosphorylation and the contractile response to either 5 x 10-8 M angiotensin II or 10-5 M histamine without inhibiting the agonist-induced increase in the intracellular free Ca2+ concentration. Furthermore, in muscle strips precontracted with either angiotensin II or histamine, addition of ANP leads to a prompt relaxation and a prompt decrease in the extent of myosin light chain phosphorylation. These data argue that ANP uncouples the initial agonist-induced Ca2+ transient from the increase in extent of myosin light chain phosphorylation either by inhibiting the Ca2+-dependent activation of myosin light chain kinase or stimulating the activity of a phosphoprotein phosphatase capable of bringing about the rapid dephosphorylation of phosphorylated myosin light chains.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1988|
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