Central inspiration increases barosensitivity of neurons in rat rostral ventrolateral medulla

T. Miyawaki, P. Pilowsky*, Q. J. Sun, J. Minson, S. Suzuki, L. Arnolda, I. Llewellyn-Smith, J. Chalmers

*Corresponding author for this work

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

Barosensitive neurons in the rostral ventrolateral medulla (RVLM) often have a respiratory-related modulation of their activity. However, the extent of the interaction between baroreceptor and respiratory inputs is controversial. The main aim of the present study was to determine the effect of central respiratory drive (CRD) on the barosensitivity of RVLM neurons. Extracellular recordings were obtained from 68 barosensitive neurons in the RVLM of anesthetized, paralyzed, and bilaterally vagotomized Sprague-Dawley rats. Examination of phrenic-triggered histograms revealed five activity patterns among barosensitive neurons: inspiratory depression (type I, n = 20), ear]y inspiratory activation (type II, n = 14), postinspiratory activation (type III, n = 18), expiratory depression (type IV, n = 5) and no modulation (type V, n = 11). In most neurons (types I and III and 56% of type II) inhibition produced by aortic nerve stimulation was greater in inspiration than in expiration. Cardiac-related modulation, as an index of natural phasic baroreceptor activation, was also greater in inspiration than expiration in type III neurons. The results demonstrate that CRD modulates the baroreflex at the level of the RVLM.

Original languageEnglish
Pages (from-to)R909-R918
Number of pages10
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume268
Issue number4
Publication statusPublished - 1995
Externally publishedYes

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