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Titolo:
BETA-RECEPTORS AND STRESS PROTEIN-70 EXPRESSION IN HYPOXIC MYOCARDIUMOF RAINBOW-TROUT AND CHINOOK SALMON
Autore:
GAMPERL AK; VIJAYAN MM; PEREIRA C; FARRELL AP;
Indirizzi:
SIMON FRASER UNIV,DEPT BIOL SCI BURNABY BC V5A 1S6 CANADA UNIV BRITISH COLUMBIA,DEPT ANIM SCI VANCOUVER BC V6T 1Z4 CANADA
Titolo Testata:
American journal of physiology. Regulatory, integrative and comparative physiology
fascicolo: 2, volume: 43, anno: 1998,
pagine: 428 - 436
SICI:
0363-6119(1998)43:2<428:BASPEI>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
ADRENERGIC SIGNAL-TRANSDUCTION; ONCORHYNCHUS-MYKISS; CIRCULATING CATECHOLAMINES; CARDIAC-PERFORMANCE; HEAT-STRESS; ADRENOCEPTORS; CELLS; GAIRDNERI; EXPOSURE; CORTISOL;
Keywords:
ONCORHYNCHUS MYKISS; ONCORHYNCHUS TSHAWYTSCHA; HEART; HYPOXIA; TEMPERATURE; CATECHOLAMINES; CORTISOL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
49
Recensione:
Indirizzi per estratti:
Citazione:
A.K. Gamperl et al., "BETA-RECEPTORS AND STRESS PROTEIN-70 EXPRESSION IN HYPOXIC MYOCARDIUMOF RAINBOW-TROUT AND CHINOOK SALMON", American journal of physiology. Regulatory, integrative and comparative physiology, 43(2), 1998, pp. 428-436

Abstract

We examined the in vivo effect of acute hypoxemia on myocardial cell-surface (sarcolemmal) beta-adrenoreceptor density (B-max) and binding affinity (K-D) and on stress protein 70 (sp70) expression by exposing rainbow trout (Oncorhynchus mykiss; 2.1-2.7 kg) to hypoxic water (3 mg/l O-2) at 15 degrees C for 6 h. This degree of hypoxia was the minimum O-2 level that these trout could tolerate without losing equilibriumand struggling violently. Hypoxic exposure reduced arterial PO2 (Pa-O2) from 98 to 26 mmHg and arterial oxygen content (Ca-O2) from 10.8 to7.4 vol/100 vol, but did not elevate epinephrine and norepinephrine levels above 10 and 90 nM, respectively. Despite the substantial reduction in blood oxygen status, the B-max and K-D of myocardial cell-surface beta-adrenoreceptors were unaffected by 6 h of hypoxic exposure. Inaddition, acute hypoxemia did not increase myocardial sp70 expression. The failure of short-term hypoxia to decrease trout myocardial beta-adrenoreceptor density clearly contrasts with the established hypoxia-mediated down-regulation shown for mammals. To further investigate theinfluence of low PO2 on salmonid myocardial beta-adrenoreceptors, binding studies were performed on the spongy (continuously exposed to deoxygenated venous blood) and compact (perfused by oxygenated blood supplied by the coronary artery) myocardia of chinook salmon. The spongy myocardium has adapted to its microenvironment of continuous low PO2 byhaving 14% more cell-surface beta-adrenoreceptors compared with the compact myocardium. There was no tissue-specific difference in XD and no evidence of sexual dimorphism in B-max or K-D. We conclude from our studies that the salmonid heart is well adapted for sustained performance under hypoxic conditions. We found that wild chinook salmon had 2.8x more cell-surface beta-adrenoreceptors compared with hatchery-reared rainbow trout. This difference suggests a significant degree of plasticity exists for fish myocardial beta-adrenoreceptors. The signals underlying such differences await further study, but are not likely to include moderate hypoxia and sexual dimorphism.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/10/20 alle ore 09:04:18