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Titolo:
Sustained high O-2 use for Ca2+ handling in rat ventricular slices under decreased free shortening after ryanodine
Autore:
Kohzuki, H; Misawa, H; Sakata, S; Ohga, Y; Takaki, M;
Indirizzi:
Nara Med Univ, Dept Physiol 2, Nara 6348521, Japan Nara Med Univ Nara Japan 6348521 iv, Dept Physiol 2, Nara 6348521, Japan
Titolo Testata:
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
fascicolo: 2, volume: 281, anno: 2001,
pagine: H566 - H572
SICI:
0363-6135(200108)281:2<H566:SHOUFC>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
SARCOPLASMIC-RETICULUM ATPASE; INCREASED OXYGEN COST; CYCLOPIAZONIC ACID; GUINEA-PIG; STUNNED MYOCARDIUM; CARDIAC MYOCYTES; CALCIUM-UPTAKE; THAPSIGARGIN; MUSCLE; RABBIT;
Keywords:
excitation-contraction coupling; sarcoplasmic reticulum Ca2+-ATPase; cyclopiazonic acid; recirculation fraction; KB-R7943; sarcolemmal Na+/Ca2+ exchanger;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Kohzuki, H Nara Med Univ, Dept Physiol 2, 840 Shijo Cho, Nara 6348521, Japan Nara Med Univ 840 Shijo Cho Nara Japan 6348521 6348521, Japan
Citazione:
H. Kohzuki et al., "Sustained high O-2 use for Ca2+ handling in rat ventricular slices under decreased free shortening after ryanodine", AM J P-HEAR, 281(2), 2001, pp. H566-H572

Abstract

We hypothesized that O-2 wasting of Ca2+ handling in the excitation-contraction coupling in ryanodine-treated failing hearts might derive from an increased external Ca2+ extrusion via Na+/Ca2+ exchanger and futile Ca2+ cycling via sarcoplasmic reticulum (SR) Ca2+-ATPase. We tested this hypothesis by mechanoenergetic studies using rat left ventricular slices. After the slices were treated with ryanodine (0.1 muM), 1-Hz free shortening significantly decreased by 78-85%, whereas the observed O-2 consumption ((V) over dot (O2)) required for total Ca2+ handling, increased from 0.79 to 1.13 ml O-2.min(-1). 100 g LV-1 (155.6% of control). We reconfirmed that cyclopiazonicacid (10 muM), a blocker of SR Ca2+-ATPase, decreased (V) over dot (O2) by75-80% in normal slices. However, 100 muM of cyclopiazonic acid was neededto inhibit the (V) over dot (O2) by 80% after ryanodine treatment. Blockade of a sarcolemmal Na+/Ca2+ exchanger by KB-R7943 (10 muM) significantly decreased (V) over dot (O2) by 45% after ryanodine treatment without significant effects on normal slices. Our results indicated that the (V) over dot (O2) increase following ryanodine treatment was derived from a net change ofan increased external Ca2+ extrusion via Na+/Ca2+ exchanger and futile Ca2 cycling via SR Ca2+-ATPase.

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Documento generato il 01/04/20 alle ore 20:30:47