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AJP - Regulatory, Integrative and Comparative Physiology, Vol 270, Issue 6 1220-R1225, Copyright © 1996 by American Physiological Society
ARTICLES |
E. Colombari, J. V. Menani and W. T. Talman
Department of Neurology, University of Iowa, Iowa City 52242, USA.
In the present study we investigated whether interruption of the chemoreceptor reflex by an electrolytic lesion of the commissural subnucleus of the nucleus tractus solitarii (commNTS) influenced pressor and bradycardic responses induced by microinjection of L-glutamate (L-Glu) into the medial NTS (mNTS) of conscious rats. Seven days after sham lesions, seven rats demonstrated significant pressor [change in mean arterial pressure (MAP) = +33 +/- 3 mmHg] and bradycardic [change in heart rate (HR) = -74 +/- 8 beats/min (bpm)] responses to chemoreceptor reflex activation by intravenous injection of KCN. Likewise, L-Glu (1 nmol in 100 nl) injected into the mNTS in sham rats induced pressor (+29 +/- 2 mmHg) and bradycardic responses (-90 +/- 8 bpm). However, in 11 rats with lesions in commNTS, pressor and bradycardic chemoreceptor reflex responses were abolished, and injection of L-Glu into the mNTS decreased MAP (-14 +/- 6 mmHg) and HR (-59 +/- 16 bpm) as is reported in anesthetized control rats. We conclude that pressor responses induced by L-Glu microinjected into the baroreceptor reflex region of mNTS in conscious rats depend on the integrity of the commNTS, which plays an important role in central chemoreceptor reflex pathways.
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  T. S. Moreira, M. A. Sato, A. C. T. Takakura, J. V. Menani, and E. Colombari Role of pressor mechanisms from the NTS and CVLM in control of arterial pressure Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2005; 289(5): R1416 - R1425. [Abstract] [Full Text] [PDF]
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 A. P. L. Abdala, A. S. Haibara, and E. Colombari Cardiovascular responses to substance P in the nucleus tractus solitarii: microinjection study in conscious rats Am J Physiol Heart Circ Physiol, July 11, 2003; 285(2): H891 - H898. [Abstract] [Full Text] [PDF]
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T. J. Scislo and D. S. O'Leary Mechanisms mediating regional sympathoactivatory responses to stimulation of NTS A1 adenosine receptors Am J Physiol Heart Circ Physiol, October 1, 2002; 283 (4): H1588 - H1599. [Abstract] [Full Text] [PDF]
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M. A. Sato, E. Colombari, and S. F. Morrison Inhibition of neurons in commissural nucleus of solitary tract reduces sympathetic nerve activity in SHR Am J Physiol Heart Circ Physiol, May 1, 2002; 282(5): H1679 - H1684. [Abstract] [Full Text] [PDF]
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D.-P. Li, D. B. Averill, and H.-L. Pan Differential roles for glutamate receptor subtypes within commissural NTS in cardiac-sympathetic reflex Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2001; 281(3): R935 - R943. [Abstract] [Full Text] [PDF]
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A. C. Rodrigues Dias, W. T. Talman, and E. Colombari Hemodynamic effects elicited by microinjection of glutamatergic agonists into NTS of conscious rats Am J Physiol Heart Circ Physiol, September 1, 2001; 281(3): H1026 - H1034. [Abstract] [Full Text] [PDF]
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 E. Colombari, M. A. Sato, S. L. Cravo, C. T. Bergamaschi, R. R. Campos Jr, and O. U. Lopes Role of the Medulla Oblongata in Hypertension Hypertension, September 1, 2001; 38(3): 549 - 554. [Abstract] [Full Text] [PDF]
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M. Akemi Sato, J. Vanderlei Menani, O. Ubriaco Lopes, and E. Colombari Lesions of the Commissural Nucleus of the Solitary Tract Reduce Arterial Pressure in Spontaneously Hypertensive Rats Hypertension, September 1, 2001; 38(3): 560 - 564. [Abstract] [Full Text] [PDF]
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T. J. Scislo and D. S. O'Leary Differential role of ionotropic glutamatergic mechanisms in responses to NTS P2x and A2a receptor stimulation Am J Physiol Heart Circ Physiol, June 1, 2000; 278(6): H2057 - H2068. [Abstract] [Full Text] [PDF]
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W.-C. Lo, C.-R. Jan, H.-T. Chiang, and C.-J. Tseng Modulatory Effects of Carbon Monoxide on Baroreflex Activation in Nucleus Tractus Solitarii of Rats Hypertension, June 1, 2000; 35(6): 1253 - 1257. [Abstract] [Full Text] [PDF]
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M. A. Sato, J. V. Menani, O. U. Lopes, and E. Colombari Enhanced pressor response to carotid occlusion in commNTS-lesioned rats: possible efferent mechanisms Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2000; 278(5): R1258 - R1266. [Abstract] [Full Text] [PDF]
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M. A. Sato, J. V. Menani, O. U. Lopes, and E. Colombari Commissural NTS Lesions and Cardiovascular Responses in Aortic Baroreceptor-Denervated Rats Hypertension, October 1, 1999; 34(4): 739 - 743. [Abstract] [Full Text] [PDF]
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A. S. Haibara, L. G. H. Bonagamba, and B. H. Machado Sympathoexcitatory neurotransmission of the chemoreflex in the NTS of awake rats Am J Physiol Regulatory Integrative Comp Physiol, January 1, 1999; 276(1): R69 - R80. [Abstract] [Full Text] [PDF]
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E. Colombari, R. L. Davisson, R. A. Shaffer, W. T. Talman, and S. J. Lewis Hemodynamic effects of L-glutamate in NTS of conscious rats: a possible role of vascular nitrosyl factors Am J Physiol Heart Circ Physiol, April 1, 1998; 274(4): H1066 - H1074. [Abstract] [Full Text] [PDF]
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