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Titolo:
PHENTOLAMINE AND HYPOXIA - MODULATION OF CONTRACTILITY AND ALPHA(1)-ADRENOCEPTORS IN ISOLATED RAT ATRIA
Autore:
FROLDI G; GUERRA L; PANDOLFO L; CHINELLATO A; RAGAZZI E; CAPARROTTA L; BOREA PA; FASSINA G;
Indirizzi:
UNIV PADUA,DEPT PHARMACOL,LARGO E MENEGHETTI 2 I-35131 PADUA ITALY UNIV PADUA,DEPT PHARMACOL I-35131 PADUA ITALY UNIV FERRARA,INST PHARMACOL I-44100 FERRARA ITALY
Titolo Testata:
Naunyn-Schmiedeberg's archives of pharmacology
fascicolo: 5, volume: 350, anno: 1994,
pagine: 563 - 568
SICI:
0028-1298(1994)350:5<563:PAH-MO>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
ALPHA-ADRENERGIC RECEPTORS; MYOCARDIAL ISCHEMIA; HEART; ADRENOCEPTORS; REPERFUSION; METABOLISM; BINDING;
Keywords:
ALPHA(1)-ADRENOCEPTORS; BETA-ADRENOCEPTORS; HYPOXIA; PHENTOLAMINE; ATRIAL FUNCTION; YOSHIDA RATS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
G. Froldi et al., "PHENTOLAMINE AND HYPOXIA - MODULATION OF CONTRACTILITY AND ALPHA(1)-ADRENOCEPTORS IN ISOLATED RAT ATRIA", Naunyn-Schmiedeberg's archives of pharmacology, 350(5), 1994, pp. 563-568

Abstract

The hypoxia-induced effects on the binding sites and affinity constant of adrenoceptors, in the presence and absence of phentolamine, were determined for atrial membranes of hearts from normal and genetically hyperlipidaemic Yoshida (YOS) rats. Atrial function was also measured during normoxia and hypoxia, in the presence and absence of phentolamine. Hypoxia increased alpha(1)-adrenoceptor density in atrial membranes of normal rats (B-max 10.6 to 26.7 fmoles/mg protein). Phentolamine prevented the increase in the B-max of alpha(1)-adrenoceptors and increased the equilibrium dissociation constant of these receptors (K-D 0.17 to 0.53 nmol/l). Beta-adrenoceptors did not change during hypoxia, but the B-max was slightly increased (26%) in the presence of phentolamine. Thus, the alpha(1)/beta ratio increased from 0.40 in normoxia to1.06 in hypoxia. In normoxic atria from YOS rats, the alpha(1)/beta ratio was already elevated (0.86) in comparison to control rats (mainlydue to a higher density of alpha(1)-adrenoceptors in atrial membranesfrom YOS rats). This ratio was not modified by hypoxia (0.84), but decreased when phentolamine was present (0.30). Hypoxia reduced the force of contraction and increased diastolic tension of atria of normal rats, while the sinus rate was not significantly modified. Phentolamine abolished the increase in diastolic tension and reduced the negative effect of hypoxia on contractile force. In YOS rat atria, functional parameters were modified by hypoxia in a qualitatively similar way to that of normal rat atria. The observed increase in alpha(1)-adrenoceptordensity during hypoxia is in accordance with the results of experiments with animal models of the ischaemic heart and with findings in human heart failure. The possible therapeutic significance of these data is considered.

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Documento generato il 07/04/20 alle ore 22:48:15