Relative contributions of cyclooxygenase- and cytochrome P450 omega-hydroxylase-dependent pathways to hypoxic dilation of skeletal muscle resistance arteries.
This study determined the contribution of prostanoids, cytochrome P450 (CP450) 4A enzyme metabolites of arachidonic acid, and other potential mediators of hypoxic dilation of isolated rat skeletal muscle resistance arteries. Gracilis arteries (GA) were viewed via television microscopy and dilator responses to hypoxia (reduction in superfusate and perfusate PO2 from approximately 145 to approximately 40 mm Hg) were measured with a video micrometer. Hypoxic dilation of gracilis arteries was severely impaired by either endothelium removal or cyclooxygenase inhibition with indomethacin, but not by nitric oxide synthase inhibition with L-NAME. Treatment of GA with 17-octadecynoic acid (17-ODYA) alone to inhibit CP450 4A enzymes significantly reduced hypoxic dilation from control levels. Treatment of vessels with N-methylsulfonyl-6-(2-proparglyoxyphenyl)hexanoic acid (MS-PPOH) to inhibit the production of epoxyeicosatrienoic acids (EETs) did not alter hypoxic dilation, although treatment with dibromo-dodecenyl-methylsulfimide (DDMS) to inhibit 20-hydroxyeicosatetraenoic acid (20-HETE) production had similar effects as 17-ODYA. Treatment of GA with 6(Z),15(Z)-20-HEDE, a competitive antagonist of the actions of 20-HETE, mimicked the effects of 17-ODYA and DDMS treatment on hypoxic dilation. These results suggest that hypoxic dilation of skeletal muscle resistance arteries primarily represents the effects of enhanced prostanoid release from vascular endothelium, although a contribution of reduced 20-HETE production via CP450 omega-hydroxylase enzymes also regulates hypoxic dilation of these vessels.
Frisbee
J C
JC
Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisc 53226, USA. jfrisbee@mcw.edu
Roman
R J
RJ
Krishna
U M
UM
Falck
J R
JR
Lombard
J H
JH
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D001158:Arteries / Q000503:physiopathology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis; D000860:Hypoxia / Q000503:physiopathology*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000098:blood supply*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000097:blood; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance; D014664:Vasodilation
D016861:Cyclooxygenase Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D006893:Hydroxyeicosatetraenoic Acids; D016718:Arachidonic Acid; C047008:17-octadecynoic acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D019001:Nitric Oxide Synthase; C409986:cytochrome P-450 omega-hydroxylase; D011451:Prostaglandin-Endoperoxide Synthases; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin