AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 2 437-R446, Copyright © 1992 by American Physiological Society

ARTICLES

Splanchnic nerve response to A5 area stimulation in rats

D. Huangfu, L. J. Hwang, T. A. Riley and P. G. Guyenet
Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908.

Microinjection of the excitatory amino acid N-methyl-D-aspartate (NMDA, 0.5 nmol) into ventrolateral pons (the A5 area) of halothane-anesthetized, paralyzed rats increased splanchnic (sSND) and renal sympathetic nerve discharges (approximately 45%) and usually decreased lumbar SND. These effects were accompanied by 1) regionally specific changes in vascular resistances, 2) an increase in the gain of the sympathetic baroreflex, and 3) modest reductions in blood pressure and heart rate. sSND activation was greatest when NMDA injections were made in the vicinity of A5 noradrenergic (NE) cells. Injection of 6-hydroxydopamine (6-OH-DA) into A5 area (after 15 days) destroyed 83% of NE neurons and reduced NMDA activation of sSND by 76%. Stimulation of sSND by NMDA in A5 area was reduced 1) 1-2 h after bilateral intraspinal injection of 6-OHDA, but not vehicle or 5,7-dihydroxytryptamine, and 2) by administration of prazosin [alpha 1-NE receptor antagonist, 1 mg/kg iv or 10-20 micrograms intrathecal (it)], but not by idazoxan (alpha 2-NE receptor antagonist, 10-20 micrograms it) or propranolol (0.2 mg/kg iv). We conclude that A5 NE cells have a visceral vasomotor sympathoexcitatory function mediated in large part by their spinal projection.

This article has been cited by other articles:

				Y.-H. Hsieh, T. E. Dick, and R. E. Siegel Adaptation to hypobaric hypoxia involves GABAA receptors in the pons Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2008; 294(2): R549 - R557. [Abstract] [Full Text] [PDF]

				C. J. Madden and A. F. Sved Cardiovascular regulation after destruction of the C1 cell group of the rostral ventrolateral medulla in rats Am J Physiol Heart Circ Physiol, December 1, 2003; 285(6): H2734 - H2748. [Abstract] [Full Text] [PDF]

				D. N. Maiorov, S. C. Malpas, and G. A. Head Influence of pontine A5 region on renal sympathetic nerve activity in conscious rabbits Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2000; 278(2): R311 - R319. [Abstract] [Full Text] [PDF]

				S. M. Barman and G. L. Gebber Classification of Caudal Ventrolateral Pontine Neurons With Sympathetic Nerve-Related Activity J Neurophysiol, November 1, 1998; 80(5): 2433 - 2445. [Abstract] [Full Text] [PDF]

				E. A. Gaudet, S. J. Godwin, and G. A. Head Role of central catecholaminergic pathways in the actions of endogenous ANG II on sympathetic reflexes Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1998; 275(4): R1174 - R1184. [Abstract] [Full Text] [PDF]

				D. Huangfu and P. G. Guyenet Autoactivity of A5 neurons: role of subthreshold oscillations and persistent Na+ current Am J Physiol Heart Circ Physiol, November 1, 1997; 273(5): H2280 - H2289. [Abstract] [Full Text] [PDF]

				D. Huangfu and P. G. Guyenet alpha 2-Adrenergic autoreceptors in A5 and A6 neurons of neonate rats Am J Physiol Heart Circ Physiol, November 1, 1997; 273(5): H2290 - H2295. [Abstract] [Full Text] [PDF]

				S. A. Deuchars, K. M. Spyer, and M. P. Gilbey Stimulation Within the Rostral Ventrolateral Medulla Can Evoke Monosynaptic GABAergic IPSPs in Sympathetic Preganglionic Neurons In Vitro J Neurophysiol, January 1, 1997; 77(1): 229 - 235. [Abstract] [Full Text] [PDF]