Electrophysiological properties of automatic fibers in rabbit atrioventricular valves

George J Rozanski

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Subsidiary atrial automaticity generated by cardiac fibers of the rabbit tricuspid valve was studied in vitro with the use of standard microelectrode techniques. The time course of diastolic depolarization of leading pacemaker fibers was characteristically biphasic over a potential range of -80 to -55 mV, with a brief primary phase of relatively steep slope and a longer secondary phase of lesser slope. The regenerative upstroke of pacemaker potentials was suppressed by cobalt ions and varied with changes in extracellular Ca2+ concentration in a manner suggesting a slow channel process. The time course of each diastolic phase, estimated by measuring slope, varied in a reproducible manner with changes in membrane potential elicited with long duration current pulses. Cesium ions reduced the slope of both diastolic phases at all potentials with greater effects on the primary diastolic phase, but spontaneous activity in the absence of current pulses was not significantly altered. Furthermore, pacemaker activity varied with changes in extracellular K+ concentration and in response to barium ions in manners suggesting the presence of a decaying K+ conductance. These experiments demonstrate the utility of valve tissue as a model of subsidiary atrial pacemaker activity and suggest the presence of current systems qualitatively similar to those observed in the sinoatrial node.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume253
Issue number4
StatePublished - Dec 1 1987

Fingerprint

Ions
Rabbits
Cesium
Sinoatrial Node
Tricuspid Valve
Microelectrodes
Barium
Cobalt
Membrane Potentials
In Vitro Techniques

ASJC Scopus subject areas

  • Physiology

Cite this

Electrophysiological properties of automatic fibers in rabbit atrioventricular valves. / Rozanski, George J.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 253, No. 4, 01.12.1987.

Research output: Contribution to journalArticle

@article{62ac5e1e9db14388a26af96250e59fae,
title = "Electrophysiological properties of automatic fibers in rabbit atrioventricular valves",
abstract = "Subsidiary atrial automaticity generated by cardiac fibers of the rabbit tricuspid valve was studied in vitro with the use of standard microelectrode techniques. The time course of diastolic depolarization of leading pacemaker fibers was characteristically biphasic over a potential range of -80 to -55 mV, with a brief primary phase of relatively steep slope and a longer secondary phase of lesser slope. The regenerative upstroke of pacemaker potentials was suppressed by cobalt ions and varied with changes in extracellular Ca2+ concentration in a manner suggesting a slow channel process. The time course of each diastolic phase, estimated by measuring slope, varied in a reproducible manner with changes in membrane potential elicited with long duration current pulses. Cesium ions reduced the slope of both diastolic phases at all potentials with greater effects on the primary diastolic phase, but spontaneous activity in the absence of current pulses was not significantly altered. Furthermore, pacemaker activity varied with changes in extracellular K+ concentration and in response to barium ions in manners suggesting the presence of a decaying K+ conductance. These experiments demonstrate the utility of valve tissue as a model of subsidiary atrial pacemaker activity and suggest the presence of current systems qualitatively similar to those observed in the sinoatrial node.",
author = "Rozanski, {George J}",
year = "1987",
month = "12",
day = "1",
language = "English (US)",
volume = "253",
journal = "American Journal of Physiology - Renal Physiology",
issn = "0363-6127",
publisher = "American Physiological Society",
number = "4",

}

TY - JOUR

T1 - Electrophysiological properties of automatic fibers in rabbit atrioventricular valves

AU - Rozanski, George J

PY - 1987/12/1

Y1 - 1987/12/1

N2 - Subsidiary atrial automaticity generated by cardiac fibers of the rabbit tricuspid valve was studied in vitro with the use of standard microelectrode techniques. The time course of diastolic depolarization of leading pacemaker fibers was characteristically biphasic over a potential range of -80 to -55 mV, with a brief primary phase of relatively steep slope and a longer secondary phase of lesser slope. The regenerative upstroke of pacemaker potentials was suppressed by cobalt ions and varied with changes in extracellular Ca2+ concentration in a manner suggesting a slow channel process. The time course of each diastolic phase, estimated by measuring slope, varied in a reproducible manner with changes in membrane potential elicited with long duration current pulses. Cesium ions reduced the slope of both diastolic phases at all potentials with greater effects on the primary diastolic phase, but spontaneous activity in the absence of current pulses was not significantly altered. Furthermore, pacemaker activity varied with changes in extracellular K+ concentration and in response to barium ions in manners suggesting the presence of a decaying K+ conductance. These experiments demonstrate the utility of valve tissue as a model of subsidiary atrial pacemaker activity and suggest the presence of current systems qualitatively similar to those observed in the sinoatrial node.

AB - Subsidiary atrial automaticity generated by cardiac fibers of the rabbit tricuspid valve was studied in vitro with the use of standard microelectrode techniques. The time course of diastolic depolarization of leading pacemaker fibers was characteristically biphasic over a potential range of -80 to -55 mV, with a brief primary phase of relatively steep slope and a longer secondary phase of lesser slope. The regenerative upstroke of pacemaker potentials was suppressed by cobalt ions and varied with changes in extracellular Ca2+ concentration in a manner suggesting a slow channel process. The time course of each diastolic phase, estimated by measuring slope, varied in a reproducible manner with changes in membrane potential elicited with long duration current pulses. Cesium ions reduced the slope of both diastolic phases at all potentials with greater effects on the primary diastolic phase, but spontaneous activity in the absence of current pulses was not significantly altered. Furthermore, pacemaker activity varied with changes in extracellular K+ concentration and in response to barium ions in manners suggesting the presence of a decaying K+ conductance. These experiments demonstrate the utility of valve tissue as a model of subsidiary atrial pacemaker activity and suggest the presence of current systems qualitatively similar to those observed in the sinoatrial node.

UR - http://www.scopus.com/inward/record.url?scp=0023631475&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023631475&partnerID=8YFLogxK

M3 - Article

VL - 253

JO - American Journal of Physiology - Renal Physiology

JF - American Journal of Physiology - Renal Physiology

SN - 0363-6127

IS - 4

ER -