Combined oxygen and glucose sensing in the carotid body

Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología and Hospital Universitario Virgen del Rocío, Universidad de Sevilla, E-41013, Seville, Spain.
Undersea & hyperbaric medicine: journal of the Undersea and Hyperbaric Medical Society, Inc (Impact Factor: 0.77). 02/2004; 31(1):113-21.
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Available from: Ricardo Pardal
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    ABSTRACT: Hypoxic stimulation of the carotid body receptors (CBR) results in a rapid hyperglycemia with an increase in brain glucose retention. Previous work indicates that neurohypophysectomy inhibits this hyperglycemic response. Here, we show that systemic arginine vasopressin (AVP) induced a transient, but significant, increase in blood glucose levels and increased brain glucose retention, a response similar to that observed after CBR stimulation. Comparable results were obtained after intracerebral infusion of AVP. Systemic AVP-induced changes were maintained in hypophysectomized rats but were not observed after adrenalectomy. Glycemic changes after CBR stimulation were inhibited by pharmacological blockage of AVP V1a receptors with a V1a-selective receptor antagonist ([beta-Mercapto-beta,beta-cyclopentamethylenepropionyl1,O-me-Tyr2, Arg8]-vasopressin). Importantly, local application of micro-doses of this antagonist to the liver was sufficient to abolish the hyperglycemic response after CBR stimulation. These results suggest that AVP is a mediator of the hyperglycemic reflex and cerebral glucose retention following CBR stimulation. We propose that hepatic activation of AVP V1a receptors is essential for this hyperglycemic response.
    Preview · Article · Jul 2006 · Journal of Applied Physiology
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    ABSTRACT: Introduction Oxygen is required as the ultimate electron acceptor in aerobic energy production. In the long run, all vertebrates need oxygen to support metabolism. In the short term, however, some animals can cope with a total lack of oxygen (anoxia), and others can tolerate reduced oxygen levels (hypoxia). Furthermore, eutrophic aquatic systems in particular are characterized by supra-atmospheric oxygen tensions (hyperoxia) during active photosynthesis of green plants. Hyperoxic conditions may also occur in the closed system of circulation, especially near the gas gland and avascular retina of fishes (Ingermann and Terwilliger, 1982 Pelster and Scheid, 1992).With regard to oxygen requirements, there is an intricate balance between reactions that produce energy and those that consume it. It is generally agreed that energy (and oxygen) consumption is reduced when adapting to conditions of low oxygen (e.g. channel arrest) (Hochachka and Lutz, 2001). However, even in conditions in which oxygen is not limiting, adjustments of metabolic rate occur (Rissanen 2006a). Because several phenomena, at both integrative and molecular levels, have turned out to be oxygen sensitive, the search for mechanisms by which oxygen is sensed has intensified in recent years.Several questions relate to how oxygen is sensed and how oxygen-dependent responses occur. First, what is actually sensed, when apparently oxygen-dependent phenomena occur? Secondly, which molecules are utilized in sensing oxygen? Thirdly, what are the pathways used in oxygen sensing–i.e. how is the primary signal converted to be used by the effector systems in an oxygen-dependent manner?
    Full-text · Chapter · Jan 2010