Differential effects from parapyramidal region and rostral ventrolateral medulla mediated by substance P

Kenneth Swiatkowski, Lynn M. Dellamano, John Vissing, Kenneth J. Rybicki, Gerald P. Kozlowski, Gary A. Iwamoto

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Rostral ventrolateral medulla (rVLM) and parapyramidal region (PPr) serve as important medullary control sites for sympathoexcitation, rVLM and PPr have direct projections to the intermediolateral cell column (IML) that are thought to be important in maintaining mean arterial blood pressure (MAP). Substance P (SP) is found in PPr neurons and in and near the subretrofacial area of the rVLM. At least some of these cells project to the IML. We investigated the involvement of SP at the IML in mediating rVLM- and PPr-evoked pressor responses in the chloraloseanesthetized cat. Pressor responses to electrical and chemical PPr and rVLM stimulation were altered after intrathecal injection, at the level of the T1-T3 spinal cord, of either SP antagonist [D-Pro2, D-Phe7, D-Trp9]-SP, SP antagonist CP 96,345, or SP antiserum. Although MAP and heart rate responses to PPr stimulation were attenuated by intrathecal SP antagonists or antiserum, MAP responses to rVLM stimulation were augmented. Previous studies have revealed differences in transmitters associated with these two areas, even though the general response of both areas is sympathoexcitatory. The present study implies that the identical substance may increase or decrease the MAP response depending on the pathway activated.

Original languageEnglish (US)
Pages (from-to)R1120-R1129
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number4 46-4
StatePublished - Oct 1999


  • Brain stem
  • CP 96,345
  • Cats
  • Intermediolateral cell column
  • Pressor responses

ASJC Scopus subject areas

  • General Medicine


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