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Titolo:
Norepinephrine kinetics in freely moving rats
Autore:
Maignan, E; Legrand, M; Aboulfath, I; Safar, M; Cuche, JL;
Indirizzi:
Broussais Fac Med, INSERM, Catecholamine Biol Res Lab, F-75270 Paris, France Broussais Fac Med Paris France F-75270 ol Res Lab, F-75270 Paris, France
Titolo Testata:
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
fascicolo: 4, volume: 281, anno: 2001,
pagine: E726 - E735
SICI:
0193-1849(200110)281:4<E726:NKIFMR>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
NORADRENALINE KINETICS; PLASMA NOREPINEPHRINE; SYMPATHETIC ACTIVITY; EXERCISING RATS; EPINEPHRINE; RELEASE; HUMANS; CATECHOLAMINES; RESPONSES; CLEARANCE;
Keywords:
norepinephrine spillover rate; norepinephrine metabolic clearance rate; epinephrine; dopamine; epinephrine hypothesis; yohimbine;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Cuche, JL 104 Rue REpubl, F-50600 St Hilaire Du Harcouet, France 104 Rue REpubl St Hilaire Du Harcouet France F-50600 t, France
Citazione:
E. Maignan et al., "Norepinephrine kinetics in freely moving rats", AM J P-ENDO, 281(4), 2001, pp. E726-E735

Abstract

Norepinephrine (NE) kinetics were investigated in freely moving (FM) and minimally stressed (MS) rats with the isotope dilution technique. 1) The mean NE spillover rate (NE-SOR) was 79 +/- 6 ng.kg(-1).min(-1), and the mean NE metabolic clearance rate (NE-MCR) 179 +/- 9 ml.kg(-1).min(-1) (n = 31). Thus the NE kinetics in FM and MS rats are much faster than in human beings,probably related to a higher sympathetic drive. 2) Whether the magnitude of NE-MCR is related to the level of plasma NE concentration was investigated. No significant correlation was calculated between plasma ME concentration and NE-MCR in 31 control rats. When plasma NE concentration was varied during either acute or chronic infusion of exogenous N-E, NE-MCR remained unchanged as long as animal hemodynamics were not altered. When plasma NE concentration was high enough to increase mean arterial pressure (MAP), NE-MCR was decreased. However, when MAP was increased within comparable magnitude,NE-MCR was decreased during ME and increased during epinephrine (Epi) infusion. Thus the existence of an alpha-/beta -adrenergic mechanism involved in the regulation of NE-MCR independent of known hemodynamic mechanisms is suggested. 3) The "epinephrine hypothesis" was revisited in FM and MS rats. At variance with humans, very high plasma Epi concentrations have to be induced to increase NE-SOR in resting rats. Furthermore, NE-MCR. was also increased, accounting for the nonsignificant increase of plasma NE concentration. Within the range of Epi concentrations with no effect on NE-SOR, an increase,of N-E release was revealed when the presynaptic alpha (2)-adrenoreceptors were partially inhibited by yohimbine. This suggests the existence of a second epinephrine hypothesis.

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Documento generato il 23/01/20 alle ore 03:22:04