ABSTRACT
Water deprivation and hypernatremia are major challenges for water and sodium homeostasis. Cellular integrity requires maintenance of water and sodium concentration within narrow limits. This regulation is obtained through engagement of multiple mechanisms and neural pathways that regulate the volume and composition of the extracellular fluid. The purpose of this short review is to summarize the literature on central neural mechanisms underlying cardiovascular, hormonal and autonomic responses to circulating volume changes, and some of the findings obtained in the last 12 years by our laboratory. We review data on neural pathways that start with afferents in the carotid body that project to medullary relays in the nucleus tractus solitarii and caudal ventrolateral medulla, which in turn project to the median preoptic nucleus in the forebrain. We also review data suggesting that noradrenergic A1 cells in the caudal ventrolateral medulla represent an essential link in neural pathways controlling extracellular fluid volume and renal sodium excretion. Finally, recent data from our laboratory suggest that these structures may also be involved in the beneficial effects of intravenous infusion of hypertonic saline on recovery from hemorrhagic shock.
Subject(s)
Humans , Blood Volume/physiology , Catecholamines/physiology , Extracellular Fluid/physiology , Medulla Oblongata/physiology , Water-Electrolyte Balance/physiology , Afferent Pathways/physiology , Aorta/innervation , Cardiovascular Physiological Phenomena , Carotid Arteries/innervation , Kidney/metabolism , Neural Pathways/physiology , Neurons/physiology , Sodium/metabolismABSTRACT
Aim To investigate the relationship between spinal cord noradrenergic neurons ? 1 adrenoceptors and the spinal analgesia of ketamine. Methods Kunming mice were used. Analgesia tests were investigated with warm water tail flick test. The effects of intrathecal injection (ith) of ketamine (50,100,200 ?g)on tail flick latency of animals were observed. And the effect of pretreatment with intrathecal 6 hydrodoapa(6 OHDA, 6?g ) and ? 1 adrenoceptor antagonist prazosin (5, 15 ?g) or terazosin (5, 15 ?g) , respectively on the spinal analgesia of ketamine (100 ?g,ith) was studied. Results Dose dependent analgesia was observed following ith ketamine (100,200 ?g, P
ABSTRACT
21 albino rats were used. The origin of the noradrenergic (NA) fibers in the septum was studied with a simultaneously combined retrograde fluorescent tracing and histofluorescence method. The results revealed that the NA neurons projecting to the septum were in A_1, A_2 and A_6 groups. The projections of A_1 were bilateral, But A_2 and A_6 projected dominantly to the ipsilateral septum, with a few to the contralateral. Retrograde labeled NA cells were localized in the rostrodorsal part of A_6 group, and scattered over the whole rostrocaudal length of A_(1,2) groups. No labeling was seen in A_4 and A_7 groups. In five of the animals, retrograde labeled NA cells were occasionally observed in A_5 group. In addition, some scattered labeled non-NA neurons were seen in the raphe and the ventrolateral reticular formation of the rostral medulla.