Vasodilation of brain surface arterioles by blockade of Na-H+ antiport and its inhibition by inhibitors of KATP channel openers

William I. Rosenblum, Enoch P. Wei, Hermes A. Kontos

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Pial artrioles of rats were monitored in vivo and found to dilate in dose-dependent fashion upon application of either benzamil or ethyl isopropyl amiloride, both of which are inhibitors of the sodium-hydrogen antiport. Antiport blockade is known to decrease the internal pH of vascular smooth muscle (VSM). The dilation was blocked by 1 μm glibenclamide, which in that dose is a selective inhibitor of ATP sensitive potassium channels (K ATP). The nitric oxide synthase inhibitor nitro-L arginine (L-NNA) also blocked the response. Previous studies of this preparation under the same experimental conditions showed that L-NNA inhibited dilation by KATP openers and that nitric oxide had no permissive action in this setting. Moreover, one study by others has demonstrated a pH sensitive site on the internal surface of KATP while another study by others has demonstrated that sodium propionate, a direct acidifier of the cell, dilates rat basilar artery in KATP-dependent fashion. Therefore, the present data support the following conclusions: Decrease of internal pH dilates brain arterioles; the response is KATP dependent; in some situations, inhibitors of nitric oxide synthase can inhibit KATP and K ATP-dependent dilations including those produced by decrease of internal pH.

Original languageEnglish
Pages (from-to)77-83
Number of pages7
JournalBrain Research
Volume1005
Issue number1-2
DOIs
StatePublished - 16 Apr 2004
Externally publishedYes

Keywords

  • Acidosis
  • Brain metabolism and blood flow
  • Hypercapnia
  • Nitric oxide synthase inhibitor
  • Other systems of CNS
  • Potassium ion channel
  • Vasodilation

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