Plasma membrane calcium ATPase overexpression in arterial smooth muscle increases vasomotor responsiveness and blood pressure.
In vascular smooth muscle cells (SMCs), several mechanisms act in concert to regulate the intracellular calcium concentration [Ca2+]i, which may in turn affect vascular tone. One such mechanism is the extrusion of Ca2+ by the plasma membrane calcium ATPase (PMCA). To address, in particular, the role of the neuronal nitric oxide synthase (nNOS)-associating isoform PMCA4b in regulating vascular tone, a doxycycline-responsive transgene for human PMCA4b was overexpressed in arterial SMCs of mice. Overexpression of hPMCA4b resulted in a 2-fold increase in total aortic PMCA4 protein expression and significant real-time RT-PCR-documented differences in the levels of endogenous mouse PMCA1, PMCA4, SERCA2, and IP3R1 gene expression in arterial SMCs. Whereas no significant difference in basal [Ca2+]i or Ca2+ sensitivity was observed in vascular SMCs or mesenteric arteries, respectively, from hPMCA4b-overexpressing versus control mice, hPMCA4b-overexpressing mice revealed a reduced set-point and increased extent of myogenic response and heightened sensitivity to vasoconstrictors. Treatment of arteries with an nNOS inhibitor resulted in a reduced set-point and increased extent of the myogenic response in control but not hPMCA4b-overexpressing mice. Moreover, aortic SMCs from hPMCA4b-overexpressing mice exhibited reduced levels of cGMP under both basal and phenylephrine-stimulated conditions. These changes were associated with significant doxycycline-reversible elevations in blood pressure. Taken together, these data show that overexpression of hPMCA4b in arterial SMCs increases vascular reactivity and blood pressure, an effect that may be mediated in part by negative regulation of nNOS.
Gros
Robert
R
Heart & Stroke Richard Lewar Center of Excellence, Department of Medicine, University of Toronto, and Toronto General Hospital Research Institute, Toronto, Ontario, Canada.
Afroze
Talat
T
You
Xiao-Mang
XM
Kabir
Golam
G
Van Wert
Ryan
R
Kalair
Waseem
W
Hoque
Abunasr E
AE
Mungrue
Imran N
IN
Husain
Mansoor
M
D000818:Animals; D001011:Aorta / Q000201:enzymology; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins; D002460:Cell Line; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005838:Genotype; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D010656:Phenylephrine / Q000494:pharmacology; D053499:Plasma Membrane Calcium-Transporting ATPases; D011189:Potassium Chloride / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology*
C506952:ATP2B1 protein, human; D027682:Cation Transport Proteins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; C109599:N(omega)-propylarginine; D010656:Phenylephrine; D011189:Potassium Chloride; D001120:Arginine; C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D053499:Plasma Membrane Calcium-Transporting ATPases; C506954:Atp2b1 protein, mouse; D000252:Calcium-Transporting ATPases; D006152:Cyclic GMP; D004318:Doxycycline; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester