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Titolo:
ACTIVATOR CALCIUM AND MYOCARDIAL-CONTRACTILITY IN FETAL SHEEP EXPOSEDTO LONG-TERM HIGH-ALTITUDE HYPOXIA
Autore:
BROWNE VA; STIFFEL VM; PEARCE WJ; LONGO LD; GILBERT RD;
Indirizzi:
LOMA LINDA UNIV,SCH MED,CTR PERINATAL BIOL,DEPT PHYSIOL LOMA LINDA CA92350 LOMA LINDA UNIV,SCH MED,CTR PERINATAL BIOL,DEPT PHYSIOL LOMA LINDA CA92350 LOMA LINDA UNIV,SCH MED,CTR PERINATAL BIOL,DEPT OBSTET & GYNECOL LOMALINDA CA 92350
Titolo Testata:
American journal of physiology. Heart and circulatory physiology
fascicolo: 3, volume: 41, anno: 1997,
pagine: 1196 - 1204
SICI:
0363-6135(1997)41:3<1196:ACAMIF>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
SARCOPLASMIC-RETICULUM; DEVELOPMENTAL-CHANGES; CARDIAC-MUSCLE; DIHYDROPYRIDINE RECEPTORS; MECHANICAL FUNCTION; RELEASE CHANNEL; GATING BEHAVIOR; RAT VENTRICLE; RYANODINE; HYPOXEMIA;
Keywords:
EXTRACELLULAR CALCIUM; INOTROPY; RYANODINE; DIHYDROPYRIDINE RECEPTOR; PN200-110;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
V.A. Browne et al., "ACTIVATOR CALCIUM AND MYOCARDIAL-CONTRACTILITY IN FETAL SHEEP EXPOSEDTO LONG-TERM HIGH-ALTITUDE HYPOXIA", American journal of physiology. Heart and circulatory physiology, 41(3), 1997, pp. 1196-1204

Abstract

We studied myocardial contractility in fetal sheep from ewes exposed to similar to 112 days of hypoxia at high altitude (3,820 m). We measured the inotropic response to extracellular Ca2+ concentration ([Ca2+](o), 0.2-10 mM) and ryanodine (10(-10) to 10(-4) M) in isometrically contracting papillary muscles and quantified dihydropyridine (DHPR) andryanodine (RyR) receptors. In hypoxic fetuses, curves describing the force[Ca2+], relationship were shifted left, and the top plateaus weredecreased by similar to 35% in both left and right ventricles. In normoxic and hypoxic fetuses, ryanodine (10(-4) M) reduced maximum activetension (T-max) to similar to 25-40% of baseline values, indicating that the sarcoplasmic reticulum was the chief source of activator Ca2+ and that Ca2+ influx alone was not sufficient to activate a contraction of normal amplitude. Hypoxia resulted in a lower T-max in the right ventricle and a lower maximum rate of rise in the left ventricle aftertreatment with ryanodine. DHPR number did not change, but RyR number and the RyR/DHPR in both ventricles were higher in hypoxic fetuses. Weconclude that hypoxia decreases contractility, possibly by reducing the availability of activator Ca2+ Further studies are needed to directly measure the Ca2+ current and intracellular Ca2+ transient and to examine myofilament protein and adenosinetriphosphatase activity.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/11/20 alle ore 21:45:13