Evidence against a cytochrome P450-derived reactive oxygen species as the mediator of the nitric oxide-independent vasodilator effect of bradykinin in the perfused heart of the rat

David J Fulton, J. C. Mcgiff, M. S. Wolin, P. Kaminski, J. Quilley

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Abstract

The coronary vasodilator effect of bradykinin (BK) in the rat is independent of NO but dependent on activation of phospholipases with involvement of cytochrome P450 mono-oxygenase (P450) and stimulation of Ca++-activated K+ channels, implicating an unidentified hyperpolarizing factor generated via P450 metabolism of arachidonic acid (AA). Because P450 activity also generates free radicals, such as superoxide, which can lead to the formation of hydrogen peroxide and hydroxyl radicals, which are vasoactive, we addressed the contribution of superoxide to the vasodilator effect of BK in the rat heart. Using rat renal microsomes as a source of P450, we verified that P450-dependent metabolism of AA generated superoxide, as detected by chemiluminescence with lucigenin. The signal was almost abolished by inhibition of P450 with clotrimazole and the superoxide scavenger 4,5-dihydroxy-1,3-benzene sulfonic acid. However, base-line superoxide formation, detected by chemiluminescence, in cardiac slices and perfused hearts was unchanged in response to BK or AA. Furthermore, in perfused hearts treated with nitroarginine and indomethacin to eliminate NO and prostaglandins and elevate perfusion pressure, dose-dependent vasodilator responses to BK were unaffected by superoxide dismutase plus catalase, a combination that abolished dilator responses to hydrogen peroxide. Similarly, the superoxide scavengers 4,5-dihydroxy-1,3-benzene sulfonic acid and 4- hydroxy-2,2,6,6-tetramethylpiperidinenoxyl were without effect on vasodilator responses to BK. Thus, the coronary vasodilator action of BK is independent of superoxide or its derivatives, which can be excluded as hyperpolarizing factors mediating NO-independent vasodilation in the rat.

Original languageEnglish (US)
Pages (from-to)702-709
Number of pages8
JournalJournal of Pharmacology and Experimental Therapeutics
Volume280
Issue number2
StatePublished - May 3 1997
Externally publishedYes

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Bradykinin
Vasodilator Agents
Superoxides
Cytochrome P-450 Enzyme System
Reactive Oxygen Species
Nitric Oxide
Arachidonic Acid
Sulfonic Acids
Luminescence
Benzene
Hydrogen Peroxide
Clotrimazole
Oxygenases
Phospholipases
Nitroarginine
Microsomes
Vasodilation
Indomethacin
Hydroxyl Radical
Catalase

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

Cite this

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title = "Evidence against a cytochrome P450-derived reactive oxygen species as the mediator of the nitric oxide-independent vasodilator effect of bradykinin in the perfused heart of the rat",
abstract = "The coronary vasodilator effect of bradykinin (BK) in the rat is independent of NO but dependent on activation of phospholipases with involvement of cytochrome P450 mono-oxygenase (P450) and stimulation of Ca++-activated K+ channels, implicating an unidentified hyperpolarizing factor generated via P450 metabolism of arachidonic acid (AA). Because P450 activity also generates free radicals, such as superoxide, which can lead to the formation of hydrogen peroxide and hydroxyl radicals, which are vasoactive, we addressed the contribution of superoxide to the vasodilator effect of BK in the rat heart. Using rat renal microsomes as a source of P450, we verified that P450-dependent metabolism of AA generated superoxide, as detected by chemiluminescence with lucigenin. The signal was almost abolished by inhibition of P450 with clotrimazole and the superoxide scavenger 4,5-dihydroxy-1,3-benzene sulfonic acid. However, base-line superoxide formation, detected by chemiluminescence, in cardiac slices and perfused hearts was unchanged in response to BK or AA. Furthermore, in perfused hearts treated with nitroarginine and indomethacin to eliminate NO and prostaglandins and elevate perfusion pressure, dose-dependent vasodilator responses to BK were unaffected by superoxide dismutase plus catalase, a combination that abolished dilator responses to hydrogen peroxide. Similarly, the superoxide scavengers 4,5-dihydroxy-1,3-benzene sulfonic acid and 4- hydroxy-2,2,6,6-tetramethylpiperidinenoxyl were without effect on vasodilator responses to BK. Thus, the coronary vasodilator action of BK is independent of superoxide or its derivatives, which can be excluded as hyperpolarizing factors mediating NO-independent vasodilation in the rat.",
author = "Fulton, {David J} and Mcgiff, {J. C.} and Wolin, {M. S.} and P. Kaminski and J. Quilley",
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T1 - Evidence against a cytochrome P450-derived reactive oxygen species as the mediator of the nitric oxide-independent vasodilator effect of bradykinin in the perfused heart of the rat

AU - Fulton, David J

AU - Mcgiff, J. C.

AU - Wolin, M. S.

AU - Kaminski, P.

AU - Quilley, J.

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