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Titolo:
Changes in the mechanisms involved in uterine contractions during pregnancy in guinea-pigs
Autore:
Coleman, HA; Hart, JDE; Tonta, MA; Parkington, HC;
Indirizzi:
Monash Univ, Dept Physiol, Clayton, Vic, Australia Monash Univ Clayton Vic Australia Dept Physiol, Clayton, Vic, Australia
Titolo Testata:
JOURNAL OF PHYSIOLOGY-LONDON
fascicolo: 3, volume: 523, anno: 2000,
pagine: 785 - 798
SICI:
0022-3751(20000315)523:3<785:CITMII>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
SMOOTH-MUSCLE CELLS; SINGLE MYOMETRIAL CELLS; RAT MYOMETRIUM; SARCOPLASMIC-RETICULUM; HORMONAL-REGULATION; CYCLOPIAZONIC ACID; POTASSIUM CURRENTS; MEMBRANE CURRENTS; CALCIUM INFLUX; CA2+;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Parkington, HC Monash Univ, Dept Physiol, Clayton, Vic, Australia Monash Univ Clayton Vic Australia Clayton, Vic, Australia
Citazione:
H.A. Coleman et al., "Changes in the mechanisms involved in uterine contractions during pregnancy in guinea-pigs", J PHYSL LON, 523(3), 2000, pp. 785-798

Abstract

1. The mechanisms involved in contraction in guinea-pig myometrium were compared at mid- and late pregnancy. Tension was recorded simultaneously witheither membrane potential or cytoplasmic calcium ([Ca2+](i)) in strips exposed briefly to prostaglandin F-2 alpha (PGF).2. PGF-induced increases in tension were underpinned by action potentials followed by sustained depolarization and biphasic increases in [Ca2+](i) atmid- (peak, 879 +/- 199 nM; sustained, 298 +/- 35 nM, n = 11) and late pregnancy (peak, 989 +/- 302 nM; sustained 178 +/- 33 nM, n = 8).3. At mid- and late pregnancy, nifedipine (10(-6) M) reduced (a) the PGF-induced increase in tension to 84 and 35%, (b) the level attained during thedepolarization by 2 and 12 mV and (c) the peak rise in [Ca2+](i) to 42 and17%. The sustained rises in [Ca2+](i) were resistant to nifedipine.4. In Ca2+-free solution (containing 1 mM EGTA), PGF elicited an increase in tension that was 26% of that in 2.5 mM Ca2+ and an increase in [Ca2+](i)(24% of the sustained level) at midpregnancy but no increase in tension or[Ca2+](i) at term.5. At both stages of pregnancy, PGF decreased the level of [Ca2+](i) required to elicit increases in tension comparable to those evoked by high K-o(+). The slope of the tension-[Ca2+](i) curves were steeper in mid- than in late pregnancy.6. In conclusion, at mid-pregnancy, the contractile response of the guinea-pig myometrium to PGF involves Ca2+ influx through L-type voltage-operatedCa2+ channels (VOCCs) and by receptor-operated mechanisms, release of Ca2from intracellular stores, and an increase in the sensitivity of the contractile apparatus to Ca2+. At term the situation is different: a modest increase in the sensitivity of the contractile apparatus to Ca2+ persists and there is a major reliance on Ca2+ influx through VOCCs.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 12/07/20 alle ore 09:39:38