Selective activation of vasomotor component of sap spectrum by
broad-band stimulation of nucleus reticularis ventrolateralis in the
rat.
Kuo, Terry B. J., Cheryl C. H. Yang, and Samuel H. H. Chan.
Center for Neuroscience, National Yang-Ming University, Taipei
11221, Taiwan, Republic of China
APStracts 3:0431H, 1996.
We evaluated the contribution of the rostral nucleus reticularis
ventrolateralis (NRVL) to the vasomotor com ponent 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 that were anesthetized with
pentobarbital sodium, paralyzed with pancuronium, and under
mechanical ventilation were used. Broad-band stimulation of the NRVL
with computer-generated rectangular current pulses (10-50 [mu]A, 1
ms), at a mean spike rate of 50 pps and randomized modulation
frequency of 0-3 Hz, elicited a site-specific and intensity-related
pressor response. Intriguingly, the corresponding auto-spectrum 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 [alpha]
-adrenergic neurotransmission.
Received 21 November 1995; accepted in final form 9 October 1996.
APS Manuscript Number H1093-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996