Genetic ablation of calcium-independent phospholipase A(2)beta causes hypercontractility and markedly attenuates endothelium-dependent relaxation to acetylcholine.
Activation of phospholipases leads to the release of arachidonic acid and lysophospholipids that play prominent roles in regulating vasomotor tone. To identify the role of calcium-independent phospholipase A(2)beta (iPLA(2)beta) in vasomotor function, we measured vascular responses to phenylephrine (PE) and ACh in mesenteric arterioles from wild-type (WT; iPLA(2)beta(+/+)) mice and those lacking the beta-isoform (iPLA(2)beta(-/-)) both ex vivo and in vivo. Vessels isolated from iPLA(2)beta(-/-) mice demonstrated increased constriction to PE, despite lower basal smooth muscle calcium levels, and decreased vasodilation to ACh compared with iPLA(2)beta(+/+) mice. PE constriction resulted in initial intracellular calcium release with subsequent steady-state constriction that depended on extracellular calcium influx. Endothelial denudation had no effect on vessel tone or PE-induced constriction although the dilation to ACh was significantly reduced in iPLA(2)beta(+/+) vessels. In contrast, vessels from iPLA(2)beta(-/-) constricted by 54% after denudation, indicating smooth muscle hypercontractility. In vivo, blood pressure, resting vessel diameter, and constriction of mesenteric vessels to PE were not different in iPLA(2)beta(-/-) vessels compared with WT mouse vessels. However, relaxation after ACh administration in situ was attenuated, indicating an endothelial inability to induce dilation in response to ACh. In cultured endothelial cells, inhibition of iPLA(2)beta with (S)-(E)-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one (BEL) decreased endothelial nitric oxide synthase phosphorylation and reduced endothelial agonist-induced intracellular calcium release as well as extracellular calcium influx. We conclude that iPLA(2)beta is an important mediator of vascular relaxation and intracellular calcium homeostasis in both smooth muscle and endothelial cells and that ablation of iPLA(2)beta causes agonist-induced smooth muscle hypercontractility and reduced agonist-induced endothelial dilation.
Dietrich
Hans H
HH
Washington Univ. School of Medicine, Dept. of Neurosurgery, 660 South Euclid Ave., Campus Box 8057, St. Louis, MO 63110, USA. Dietrich_H@wustl.edu
Abendschein
Dana R
DR
Moon
Sung Ho
SH
Nayeb-Hashemi
Neema
N
Mancuso
David J
DJ
Jenkins
Christopher M
CM
Kaltenbronn
Kevin M
KM
Blumer
Kendall J
KJ
Turk
John
J
Gross
Richard W
RW
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D054522:Group VI Phospholipases A2 / Q000235:genetics / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D008297:Male; D008638:Mesenteric Arteries / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D054512:Phospholipases A2, Calcium-Independent / Q000235:genetics* / Q000502:physiology*; D010766:Phosphorylation; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D052250:Nitric Oxide Synthase Type III; D054522:Group VI Phospholipases A2; D054512:Phospholipases A2, Calcium-Independent; C516476:Pla2g6 protein, mouse; D000109:Acetylcholine; D002118:Calcium
J Biol Chem. 2004 Sep 10;279(37):38194-200
15252026
J Physiol. 2002 Aug 1;542(Pt 3):929-37
12154190
J Biol Chem. 2007 Aug 31;282(35):25278-89
17613534
Br J Pharmacol. 1997 Jan;120(1):1-6
9117082
J Biol Chem. 2006 Jul 28;281(30):20958-20973
16732058
Am J Physiol Heart Circ Physiol. 2009 Aug;297(2):H836-45
19542492
Am J Physiol. 1993 Feb;264(2 Pt 2):H653-9
8447477
J Pharmacol Exp Ther. 2003 Jan;304(1):139-44
12490584
J Biol Chem. 2004 Nov 19;279(47):48968-75
15364929
J Biol Chem. 2003 Apr 4;278(14):11909-15
12547829
J Biol Chem. 2002 Sep 6;277(36):32807-14
12089145
J Cereb Blood Flow Metab. 2002 Oct;22(10):1239-47
12368663
Curr Biol. 1999 Jul 29-Aug 12;9(15):845-8
10469573
Endocrinology. 2001 Aug;142(8):3317-23
11459773
Br J Pharmacol. 1999 Oct;128(3):653-8
10516645
Arterioscler Thromb Vasc Biol. 2003 Feb 1;23(2):218-23
12588762
J Biol Chem. 2006 Nov 24;281(47):35709-16
16966332
J Vasc Res. 2003 Sep-Oct;40(5):480-90
14583659
Am J Physiol Heart Circ Physiol. 2008 Dec;295(6):H2466-74
18952717
Am J Physiol Heart Circ Physiol. 2002 Apr;282(4):H1255-61
11893559
J Physiol. 2002 Feb 15;539(Pt 1):93-106
11850504
Br J Pharmacol. 1997 Jun;121(3):588-94
9179404
J Biol Chem. 1997 Jan 17;272(3):1522-6
8999823
J Pharmacol Exp Ther. 2002 Sep;302(3):918-23
12183647
J Clin Endocrinol Metab. 2010 Feb;95(2):920-7
20022989
Biochim Biophys Acta. 1996 Jan 19;1299(2):267-77
8555273
Am J Physiol Heart Circ Physiol. 2008 Mar;294(3):H1183-7
18156193
Biochim Biophys Acta. 2000 Oct 31;1488(1-2):1-19
11080672
Pharmacol Ther. 2009 May;122(2):140-9
19285526
Eur J Biochem. 1999 Jun;262(2):575-85
10336645
Br J Pharmacol. 2004 Jan;141(2):269-76
14707030
Am J Physiol. 1994 Apr;266(4 Pt 2):H1681-6
8184948
Stroke. 2003 Jun;34(6):1473-8
12730558
J Biol Chem. 1985 Mar 25;260(6):3440-50
3838314
Biochemistry. 2001 Dec 11;40(49):14921-31
11732912
Am J Physiol Heart Circ Physiol. 2001 Feb;280(2):H767-76
11158976
Arch Biochem Biophys. 2007 Dec 1;468(1):114-20
17963719
Biochem Biophys Res Commun. 1997 Feb 24;231(3):844-7
9070907
FEBS Lett. 2003 Nov 6;554(1-2):127-32
14596926
Am J Physiol. 1991 Sep;261(3 Pt 2):H950-9
1887938
Angiogenesis. 2001;4(2):91-102
11806248