Journal
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
Volume 287, Issue 3, Pages H1089-H1095Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpheart.00627.2003
Keywords
myogenic vasoconstriction; 20-hydroxyeicosatetraenoic acid; cytochrome P-450 oxygenases; vascular reactivity
Funding
- NHLBI NIH HHS [HL-34300, HL-18579] Funding Source: Medline
- NIDDK NIH HHS [DK-38226] Funding Source: Medline
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Cytochrome P-450-4A1 (CYP4A1) is an omega-hydroxylase that catalyzes the metabolism of arachidonic acid to 20-hydroxy-eicosatetraenoic acid (20-HETE). The goal of this study was to determine the vasomotor consequences of vascular overexpression of CYP4A1. Isolated rat gracilis muscle arterioles transfected ex vivo with an expression plasmid containing CYP4A1 cDNA expressed more CYP4A protein than vessels transfected with the control plasmid. In arterioles pressurized to 80 mmHg, the internal diameter of vessels transfected with CYP4A1 cDNA ( 55 +/- 3 mum) was surpassed ( P < 0.05) by that of vessels transfected with control plasmid ( 97 +/- 4 μm). Treatment with a CYP4A inhibitor (N-methylsulfonyl-12,12-dibromododec-11-enamide; DDMS) or with an antagonist of 20-HETE actions [20-hydroxyeicosa-6(Z), 15(Z)-dienoic acid; 20-HEDE] elicited robust dilation of arterioles transfected with CYP4A1 cDNA, whereas the treatment had little or no effect in vessels transfected with control plasmid. Examination of the intraluminal pressure-internal diameter relationship revealed that pressure increments over the range of 40 - 100 mmHg elicited a more intense ( P < 0.05) myogenic constrictor response in arterioles transfected with CYP4A1 cDNA than in those with control plasmid. Arterioles transfected with CYP4A1 cDNA also displayed enhanced sensitivity to the constrictor action of phenylephrine. Treatment with DDMS or 20-HEDE greatly attenuated the constrictor responsiveness to both constrictor stimuli in vessels overexpressing CYP4A1, whereas the treatment had much less effect in control vessels. These data suggest that CYP4A1 overexpression promotes constriction of gracilis muscle arterioles by intensifying the responsiveness of vascular smooth muscle to constrictor stimuli. This effect of CYP4A1 overexpression appears to be mediated by a CYP4A1 product.
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