Biomaterial Database

A5 noradrenergic neurons and the carotid sympathetic chemoreflex. 1994

N Koshiya, and P G Guyenet

Department of Pharmacology, University of Virginia Health Sciences Center, Charlottesville 22908.

Inhibition of neural activity in the caudal ventrolateral pons (A5 area) by microinjection of muscimol (Mus) attenuates (-65%) the carotid sympathetic chemoreflex (SChR) without altering the concomitant activation of the phrenic nerve (PND). The present study, performed in urethan-anesthetized rats, explores the possibility that activation of the noradrenergic (NE) neurons of the A5 area is involved in the SChR. The NE neuron-selective toxin 6-hydroxydopamine (6-OHDA) was microinjected bilaterally into the spinal cord at T2 level (4 micrograms). This dose reduced the SChR by 55% (n = 5) 90 min after injection, while 0.4 microgram of 6-OHDA produced no effect (n = 5). In seven rats that had received 250 micrograms 6-OHDA intracisternally 2 wk before, Mus injections into the A5 area failed to attenuate the SChR. These rats also had a lower resting mean arterial pressure than controls (97 vs. 112 mmHg). Spinal intrathecal injection of alpha-adrenergic receptor antagonists (prazosin, 10 and 20 micrograms) or phentolamine (20 and 40 micrograms) attenuated resting sympathetic nerve discharge (SND) and SChR in a roughly proportional manner (25-40%); the beta-adrenergic antagonist nadolol (10 and 20 microgram(s) intrathecally) attenuated the SChR selectively but modestly (-10%). The results are generally compatible with the hypothesis that A5 NE neurons and particularly their spinal cord projection could play a facilitating role in the SChR. However, clear evidence that A5 cells contribute selectively to sympathoactivation during chemoreceptor stimulation by releasing NE in the spinal cord could not be obtained.

UI	MeSH Term	Description	Entries
D007278	Injections, Spinal	Introduction of therapeutic agents into the spinal region using a needle and syringe.	Injections, Intraspinal,Injections, Intrathecal,Intraspinal Injections,Intrathecal Injections,Spinal Injections,Injection, Intraspinal,Injection, Intrathecal,Injection, Spinal,Intraspinal Injection,Intrathecal Injection,Spinal Injection
D008297	Male		Males
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D009638	Norepinephrine	Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic.	Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D011149	Pons	The front part of the hindbrain (RHOMBENCEPHALON) that lies between the MEDULLA and the midbrain (MESENCEPHALON) ventral to the cerebellum. It is composed of two parts, the dorsal and the ventral. The pons serves as a relay station for neural pathways between the CEREBELLUM to the CEREBRUM.	Pons Varolii,Ponte,Pons Varolius,Pontes,Varolii, Pons,Varolius, Pons
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D002339	Carotid Arteries	Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery.	Arteries, Carotid,Artery, Carotid,Carotid Artery
D002628	Chemoreceptor Cells	Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.	Chemoreceptive Cells,Cell, Chemoreceptive,Cell, Chemoreceptor,Cells, Chemoreceptive,Cells, Chemoreceptor,Chemoreceptive Cell,Chemoreceptor Cell
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013116	Spinal Cord	A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.	Coccygeal Cord,Conus Medullaris,Conus Terminalis,Lumbar Cord,Medulla Spinalis,Myelon,Sacral Cord,Thoracic Cord,Coccygeal Cords,Conus Medullari,Conus Terminali,Cord, Coccygeal,Cord, Lumbar,Cord, Sacral,Cord, Spinal,Cord, Thoracic,Cords, Coccygeal,Cords, Lumbar,Cords, Sacral,Cords, Spinal,Cords, Thoracic,Lumbar Cords,Medulla Spinali,Medullari, Conus,Medullaris, Conus,Myelons,Sacral Cords,Spinal Cords,Spinali, Medulla,Spinalis, Medulla,Terminali, Conus,Terminalis, Conus,Thoracic Cords