Inositol hexakisphosphate excites rat medullary sympathoexcitatory neurons in vivo

Miao kun Sun, Claes Wahlestedt, Donald J. Reis

Research output: Contribution to journalArticle

16 Scopus citations


Inositol hexakisphosphate (IP6) was microinjected into the rostral venttrolateral reticular nucleus or iontophoresed onto reticulospinal sympathoexcitatory neurons of the nucleus in anesthetized rats. IP6 (5-500 pmol) induced a dose-dependent potent and prolonged elevation of arterial pressure which was mimicked by microinjection of ethyleneglycol-bis (β-aminoethylether) N,N,N′,N′-tetraacetic acid (EGTA), while myo-inositol was ineffective. Iontophoretic application of IP6 and EGTA excited the medullary sympathoexcitatory neurons but myo-inositol had no effect. Ihe effect of IP6 on firing rate of the sympathoexcitatory neurons was abolished by co-administration of Ca2+ ions onto these neurons. The results indicate that IP6 acts extracellularly to excite the medullary sympathoexcitatory neurons. The excitatory actions of IP6 may depend, at least in part, on a calcium-chelating action. Chelation of extracellular Ca2+ might be a physiological action of IP6.

Original languageEnglish (US)
Pages (from-to)9-16
Number of pages8
JournalEuropean Journal of Pharmacology
Issue number1
StatePublished - Apr 29 1992
Externally publishedYes


  • Inositol hexakisphosphate
  • Medulla (rostal ventrolateral)
  • Phytic acid
  • Vasomotor neurons

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Pharmacology

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