AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 4 909-R918, Copyright © 1995 by American Physiological Society

ARTICLES

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 and J. Chalmers
Department of Medicine, Flinders Medical Centre, Bedford Park, Australia.

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), early 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.

This article has been cited by other articles:

				D. M. Baekey, T. E. Dick, and J. F. R. Paton Pontomedullary transection attenuates central respiratory modulation of sympathetic discharge, heart rate and the baroreceptor reflex in the in situ rat preparation Exp Physiol, July 1, 2008; 93(7): 803 - 816. [Abstract] [Full Text] [PDF]

				S. McMullan, A. K. Goodchild, and P. M. Pilowsky Circulating angiotensin II attenuates the sympathetic baroreflex by reducing the barosensitivity of medullary cardiovascular neurones in the rat J. Physiol., July 15, 2007; 582(2): 711 - 722. [Abstract] [Full Text] [PDF]

				B. J. Barnes, C.-M. Tuong, and N. M. Mellen Functional Imaging Reveals Respiratory Network Activity During Hypoxic and Opioid Challenge in the Neonate Rat Tilted Sagittal Slab Preparation J Neurophysiol, March 1, 2007; 97(3): 2283 - 2292. [Abstract] [Full Text] [PDF]

				T. S. Moreira, A. C. Takakura, E. Colombari, and P. G. Guyenet Central chemoreceptors and sympathetic vasomotor outflow J. Physiol., November 15, 2006; 577(1): 369 - 386. [Abstract] [Full Text] [PDF]

				S. C. Mobley, D. A. Mandel, and A. M. Schreihofer Systemic Cholecystokinin Differentially Affects Baro-activated GABAergic Neurons in Rat Caudal Ventrolateral Medulla J Neurophysiol, November 1, 2006; 96(5): 2760 - 2768. [Abstract] [Full Text] [PDF]

				D. A. Mandel and A. M. Schreihofer Central respiratory modulation of barosensitive neurones in rat caudal ventrolateral medulla J. Physiol., May 1, 2006; 572(3): 881 - 896. [Abstract] [Full Text] [PDF]

				H. Wang, M. C. Weston, T. J. McQuiston, R. L. Stornetta, and P. G. Guyenet Neurokinin-1 receptor-expressing cells regulate depressor region of rat ventrolateral medulla Am J Physiol Heart Circ Physiol, December 1, 2003; 285(6): H2757 - H2769. [Abstract] [Full Text] [PDF]

				H.-J. Habler, T. Bartsch, and W. Janig Rhythmicity in Single Fiber Postganglionic Activity Supplying the Rat Tail J Neurophysiol, May 1, 1999; 81(5): 2026 - 2036. [Abstract] [Full Text] [PDF]

				J. D. Laiprasert, R. C. Rogers, and C. M. Heesch Neurosteroid modulation of arterial baroreflexsensitive neurons in rat rostral ventrolateral medulla Am J Physiol Regulatory Integrative Comp Physiol, April 1, 1998; 274(4): R903 - R911. [Abstract] [Full Text] [PDF]