Neuropeptide YY1 receptors-mediated increase in intracellular Ca2+ concentration via phospholipase C-dependent pathway in porcine aortic smooth muscle cells.
In porcine aortic smooth muscle cells, neuropeptide Y (NPY) stimulates mobilization of CA(2+) from intracellular store sites via Y1 receptors. However, it has been debated whether or not Ca(2+) mobilization by Y1 receptors depends on the generation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] following activation of phospholipase C. To examine this question, we studied the effect of U73122, an inhibitor of phospholipase C-mediated inositol phosphate accumulation on the NPY-induced rise in cytosolic free Ca(2+) concentration ([Ca(2+)]i) in comparison with that on angiotensin II (AII)-induced [Ca(2+)]i increase, which is dependent on Ins(1,4,5)P3 generation. Digital-imaging microscopy study using the Ca(2+)-sensitive dye fura-2 revealed that application of AII induced a rapid but transient [Ca(2+)]i increase in a single cell, arising from intracellular calcium stores. Application of NPY to the same cell induced a [Ca(2+)]i rise with a pattern similar to that induced by AII. AII increased the formation of Ins(1,4,5)P3 by about 3.0 fold, while the NPY-induced [Ca(2+) formation was very small. U73122 completely inhibited not only Ins(1,4,5)P3 synthesis, but also Ca(2+) mobilization induced by either agonist. The effect of U73122 on the NPY-induced Ca(2+)i increase was about 10-fold more potent that on the AII-induced one. U73343, an inactive analog of U733343, had no influence on any of the AII- and NPY-mediated effects. Herbimycin A completely inhibited the platelet-derived growth factor-induced [Ca(2+]i increase but had no effect on the NPY-induced [Ca(2+)]i increase, indicating that phospholipase C-gamma is not involved in the NPY effect. These results suggest that NPY-induced Ca2+ mobilization from intracellular stores in porcine smooth muscle cells is secondary to the very small generation of Ins(1,4,5)P3 following stimulation of phospholipase C-beta, which may account for the hypersensitivity of the NPY effect to U73122.
Shigeri
Y
Y
Shionogi Research Laboratories, Shionogi and Co., Ltd., Osaka.
Nakajima
S
S
Fujimoto
M
M
D000804:Angiotensin II / Q000187:drug effects / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D016227:Benzoquinones; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D007424:Intracellular Fluid / Q000378:metabolism; D047029:Lactams, Macrocyclic; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D009478:Neuropeptide Y / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology; D017476:Receptors, Neuropeptide Y / Q000502:physiology*; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013552:Swine; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*
D016227:Benzoquinones; D004963:Estrenes; D047029:Lactams, Macrocyclic; D009478:Neuropeptide Y; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D011809:Quinones; D017476:Receptors, Neuropeptide Y; D000804:Angiotensin II; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C074854:U 73343; D005576:Colforsin; D017828:Rifabutin; C020754:herbimycin; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D010738:Type C Phospholipases; D002118:Calcium