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Titolo:
ACTIVATION OF CARDIAC TISSUE BY EXTRACELLULAR ELECTRICAL SHOCKS - FORMATION OF SECONDARY SOURCES AT INTERCELLULAR CLEFTS IN MONOLAYERS OF CULTURED MYOCYTES
Autore:
FAST VG; ROHR S; GILLIS AM; KLEBER AG;
Indirizzi:
UNIV ALABAMA,CARDIAC RHYTHM MANAGEMENT LAB,B149 VOLKER HALL,1670 UNIVBLVD BIRMINGHAM AL 35233 UNIV BERN,DEPT PHYSIOL CH-3012 BERN SWITZERLAND
Titolo Testata:
Circulation research
fascicolo: 3, volume: 82, anno: 1998,
pagine: 375 - 385
SICI:
0009-7330(1998)82:3<375:AOCTBE>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
RAT-HEART CELLS; ANISOTROPIC CONDUCTION; VENTRICULAR MYOCYTES; OPTICAL RECORDINGS; MICROSCOPIC LEVEL; PATTERNED GROWTH; LIMINAL LENGTH; RABBIT HEART; DEFIBRILLATION; MUSCLE;
Keywords:
STIMULATION; DEFIBRILLATION; OPTICAL MAPPING; VOLTAGE-SENSITIVE DYE; CELL CULTURES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
41
Recensione:
Indirizzi per estratti:
Citazione:
V.G. Fast et al., "ACTIVATION OF CARDIAC TISSUE BY EXTRACELLULAR ELECTRICAL SHOCKS - FORMATION OF SECONDARY SOURCES AT INTERCELLULAR CLEFTS IN MONOLAYERS OF CULTURED MYOCYTES", Circulation research, 82(3), 1998, pp. 375-385

Abstract

This study investigated the activation of cardiac tissue by ''secondary sources,'' which are localized changes of the transmembrane potential (V-m) during the application of strong extracellular electrical shocks far from the shock electrodes, in cultures of neonatal rat myocytes. Cell monolayers with small intercellular clefts (length, 45 to 270 mu m; width, 20 to 70 mu m [mean+/-SD, 54+/-13 mu m]; n=46) were produced using a technique of directed cell growth. Changes in V-m relativeto the action potential amplitude (Delta V-m/APA) were measured usinga fluorescent voltage-sensitive dye and a 10X10 photodiode array. Shocks with voltage gradients of 4 to 18 V/cm were applied across the clefts during either the action potential (AP) plateau or diastole. During the AP plateau, shocks induced secondary sources in the form of localized hyperpolarizations and depolarizations in the regions immediately adjacent to opposite sides of the clefts. The strength of the secondary sources, defined as the difference of Delta V-m/APA across a cleft, increased with increasing cleft length or increasing electrical field gradient. For shocks with a gradient of 8.5 V/cm, the estimated critical cleft length necessary to reach a V-m level corresponding to the diastolic threshold of excitation was 171+/-7 mu m. Accordingly, shocks with average strength of 8.2 V/cm applied during diastole produced secondary sources that directly excited cells adjacent to the clefts when the cleft length was 196+/-53 mu m (n=14) and that failed when the cleft length was 84+/-23 mu m (n=9, P<001). The area of earliest excitation in such cases coincided with the area of maximal depolarization induced during the plateau phase. These data suggest that small inexcitable obstacles may contribute to the V-m changes during the application of strong extracellular electrical shocks in vivo.

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Documento generato il 02/04/20 alle ore 10:57:39