Atrial natriuretic peptide inhibits the agonist-induced increase in extent of myosin light chain phosphorylation in aortic smooth muscle.
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.
Paglin
S
S
Cardiovascular Institute, Boston University School of Medicine, Massachusetts 02118.
Takuwa
Y
Y
Kamm
K E
KE
Stull
J T
JT
Gavras
H
H
Rasmussen
H
H
D000331:Aequorin / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology; D008163:Luminescent Measurements; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D011817:Rabbits
D000804:Angiotensin II; D000331:Aequorin; D006632:Histamine; D009320:Atrial Natriuretic Factor; D009218:Myosins; D002118:Calcium