Inositol hexakisphosphate excites rat medullary sympathoexcitatory neurons in vivo

Miao kun Sun, Claes Wahlestedt, Donald J. Reis

Research output: Contribution to journalArticlepeer-review

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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