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Titolo:
Food deprivation increases alpha(2)-adrenoceptor-mediated modulation of jejunal epithelial transport in young and adult rats
Autore:
Lucas-Teixeira, V; Vieiua-Coelho, MA; Serrao, MP; Soares-da-Silva, P;
Indirizzi:
Fac Med, Inst Pharmacol & Therapeut, P-4200 Porto, Portugal Fac Med Porto Portugal P-4200 rmacol & Therapeut, P-4200 Porto, Portugal
Titolo Testata:
JOURNAL OF NUTRITION
fascicolo: 10, volume: 130, anno: 2000,
pagine: 2461 - 2466
SICI:
0022-3166(200010)130:10<2461:FDIAMO>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
ION-TRANSPORT; ALPHA-2-ADRENERGIC RECEPTOR; GROUND-SQUIRREL; RABBIT ILEUM; BINDING; STARVATION; MALNUTRITION; SECRETION; INTESTINE; YOHIMBINE;
Keywords:
rat jejunum; alpha(2)-adrenoceptors; Na+,K+,2Cl(-)-co-transporter; Na+K+-ATPase;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Soares-da-Silva, P Fac Med, Inst Pharmacol & Therapeut, P-4200 Porto, Portugal Fac Med Porto Portugal P-4200 P-4200 Porto, Portugal
Citazione:
V. Lucas-Teixeira et al., "Food deprivation increases alpha(2)-adrenoceptor-mediated modulation of jejunal epithelial transport in young and adult rats", J NUTR, 130(10), 2000, pp. 2461-2466

Abstract

This study examined the effect of food deprivation on the jejunal responseto alpha(2)-adrenoceptor activation in young (20-d-old) and adult (60-d-old) rats, using short-circuit (I-SC) measurements in the absence or presenceof furosemide (1 mmol/L). The effect of alpha(2)-adrenoceptor stimulation by 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK 14,304; 0.3-3000 nmol/L) was a concentration-dependent decrease in I-SC with similarhalf-maximal effective concentration (EC50; 12.3 +/- 1.1 vs. 9.6 +/- 1.1 nmol/L) and maximal effect (E-max; 70.6 +/- 6.9 vs. 80.6 +/- 4.5% of reduction) values in adult food-deprived and fed rats. The effect of UK 14,304 on I-SC in fed and food-deprived rats was markedly (P < 0.05) attenuated by furosemide (1 mmol/L). E-max values for UK 14,304 in 20-d-old food-deprived rats were higher (P < 0.05) than those observed in fed rats (93.3 +/- 3.3 vs. 67.0 +/- 11.3% of reduction), without differences in EC50 values. The effect of UK 14,304 on I,, in 20-d-old fed rats was completely abolished by furosemide (1 mmol/L). In food-deprived young rats, the effect of UK 14,304 was also markedly (P < 0.05) antagonized by furosemide, but not completely abolished. Specific [H-3]-rauwolscine binding in membranes from jejunal epithelial cells revealed the presence of a single class of binding sites, withan apparent K-D in the low nmol/L range. In 20-d-old food-deprived rats, specific [H-3]-rauwolscine binding was markedly increased, and this was reversed by refeeding. Na+,K+-ATPase activity in isolated jejunal epithelial cells from 60-d-old fed rats was twice that in 20-d-old fed rats [117 +/- 14 vs. 52 +/- 5 nmol free inorganic phosphorus/(mg protein min)]. Food deprivation in adult rats, but not in 20-d-old rats, was accompanied by a significant decrease in Na+,K+-ATPase activity. In both young and adult rats (fed and food-deprived), UK 14,304 did not affect Na+,K+-ATPase activity. In conclusion, food deprivation in 20-d-old rats enhanced the response to alpha(2)-adrenoceptor stimulation. This effect, which depends primarily on the stimulation of a furosemide-sensitive antisecretory mechanism, is suggested to result from increases in the number of jejunal epithelial alpha(2)-adrenoceptors.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/01/20 alle ore 11:38:55