Selective activation of vasomotor component of SAP spectrum by nucleus reticularis ventrolateralis in rats

Terry B.J. Kuo, Cheryl C.H. Yang, Samuel H.H. Chan

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

We evaluated the contribution of the rostral nucleus reticularis ventrolateralis (NRVL) to the vasomotor component in the spectrum of systemic arterial pressure (SAP) signals by quantifying the transfer function between electrical stimulation of this medullary nucleus and the SAP response. Sprague-Dawley rats anesthetized with pentobarbital sodium, paralyzed with pancuronium, and mechanically ventilated were used. Broad-band stimulation of the NRVL with computer-generated rectangular current pulses (10-50 μA, 1 ms), at a mean spike rate of 50 pulses/s and randomized modulation frequency of 0-3 Hz, elicited a site-specific and intensity-related pressor response. Intriguingly, the corresponding autospectrum of SAP signals exhibited prevailing power density only in the lower frequency range (0-0.8 Hz). This low-pass response characteristic was confirmed by the observation that 90% of the total magnitude of transfer function between NRVL stimulation and SAP response concentrated between 0 and 0.6 Hz. The magnitude of NRVL-SAP transfer function was significantly reduced by phentolamine or prazosin but appreciably enhanced by yohimbine. We conclude that the NRVL may contribute to the very-low (0-0.25 Hz)- and low (0.25-0.8 Hz)-frequency components of the SAP spectrum, which are believed to reflect sympathetic modulation on vasomotor activity via α-adrenergic neurotransmission.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume272
Issue number1 41-1
Publication statusPublished - 1997
Externally publishedYes

Keywords

  • alpha-adrenergic neurotransmission
  • broad-band stimulation
  • coherence
  • cross-spectral analysis
  • phase and magnitude of transfer function
  • sympathetic vasomotor tone
  • systemic arterial pressure

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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