title: Neuropeptide Y stimulation of myosin light chain phosphorylation in cultured aortic smooth muscle cells.
abstract: Neuropeptide Y (NPY) is released from an extensive network of postganglionic sympathetic perivascular neurons. NPY has been shown to affect vascular tone postsynaptically by 1) directly stimulating contraction; 2) inhibiting vasorelaxation; and 3) potentiating contraction elicited by exogenous vasoconstrictors. The molecular mechanisms mediating these effects of NPY are undefined. Therefore, we examined the possibility that NPY could stimulate smooth muscle contraction through myosin light chain phosphorylation in cultured porcine aortic smooth muscle cells. NPY (100 nM) caused a rapid, transient increase in myosin light chain (MLC) phosphorylation, an important regulatory event in the initiation of smooth muscle contraction. NPY-stimulated MLC phosphorylation was prevented by preincubation of cells with pertussis toxin and was independent of extracellular Ca2+. In parallel studies, NPY alone had no detectable effect on cellular cAMP or cGMP content; however, NPY potently inhibited forskolin-stimulated cAMP accumulation (IC50 = 0.03 nM) through a pertussis toxin-sensitive pathway. NPY had no detectable effect on basal phosphoinositide hydrolysis or protein kinase C activation but enhanced angiotensin II-stimulated production of inositol phosphates and activation of protein kinase C. These results indicate that NPY-stimulated MLC phosphorylation can occur in the absence of detectable changes in cAMP content, cGMP content, inositol phosphate production, or protein kinase C activation; however, the interactions between NPY and other vasoactive agents may be mediated by the indirect effects of NPY on adenylate cyclase activity and phosphoinositide hydrolysis.
authors.affiliation: Howard Hughes Medical Institute Laboratories, Durham, North Carolina.
authors.forename: L A
authors.initials: LA
authors.lastname: Lobaugh
authors.forename: P J
authors.initials: PJ
authors.lastname: Blackshear
mesh_terms: D037361:Adenylate Cyclase Toxin; D000818:Animals; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D009478:Neuropeptide Y / Q000494:pharmacology*; D037342:Pertussis Toxin; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D037361:Adenylate Cyclase Toxin; D007295:Inositol Phosphates; D009478:Neuropeptide Y; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011493:Protein Kinase C; D009218:Myosins; D006152:Cyclic GMP; D002118:Calcium