Mechanism of ATP-induced local and conducted vasomotor responses in isolated rat cerebral penetrating arterioles

Hans H. Dietrich, Tetsuyoshi Horiuchi, Chuanxi Xiang, Kazuhiro Hongo, J R Falck, Ralph G. Dacey

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Background: Adenosine triphosphate (ATP), a potent vascular regulator in the cerebral circulation, initiates conducted vasomotor responses which may be impaired after pathological insults. We analyzed the mechanism of ATP-induced local vasomotor responses and their effect on conducted vasomotor responses in rat cerebral penetrating arterioles. Methods: Arterioles were cannulated and their internal diameter monitored. Vasomotor responses to ATP were observed in the presence or absence of inhibitors, or after endothelial impairment. Smooth muscle membrane potentials were measured in some vessels. Results: Microapplication of ATP produced a biphasic response (constriction followed by dilation), which resulted in conducted dilation preceded by a membrane hyperpolarization. α,β-methylene-ATP or pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS) blunted the ATP-mediated constriction and enhanced local and conducted dilation. N ω-monomethyl-L-arginine, endothelial impairment and N-methylsulfonyl-6-(2-propargyloxyphenyl) hexanamide (MS-PPOH) reduced the local dilation caused by ATP. The conducted dilation was attenuated by MS-PPOH and endothelial impairment, but not Nω-monomethyl-L-arginine or indomethacin. Conclusion: ATP-induced conducted dilation is preceded by membrane hyperpolarization. Local ATP induces initial local constriction via smooth-muscle P2X1 and subsequent dilation via endothelial P 2Y receptors. Nitric oxide, cytochrome P450 metabolites, and intermediate and large conductance KCa channels mediate dilation caused by ATP. ATP-induced conducted dilation is dependent upon both the endothelium and cytochrome P450 metabolites.

Original languageEnglish (US)
Pages (from-to)253-264
Number of pages12
JournalJournal of Vascular Research
Volume46
Issue number3
DOIs
StatePublished - Apr 2009

Keywords

  • Adenosine 5′-triphosphate
  • Cerebrovascular circulation
  • Cytochrome P450
  • Microcirculation
  • P receptors
  • Potassium channels

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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