Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by α-adrenergic stimulation in the presence of elevated calcium levels

S. Kimura, J. S. Cameron, P. L. Kozlovskis, A. L. Bassett, Robert J Myerburg

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

We studied the ability of α-adrenergic stimulation to induce delayed afterdepolarizations and triggered activity in Purkinje fibers from cat hearts in the presence of an elevated Ca++ concentration. Delayed afterdepolarizations could not be induced at drive cycle lengths of 200 to 500 msec in the presence of extracellular Ca++ concentrations of 2.7 to 8.1 mM. However, the addition of 10-5M phenylephrine in the presence of 5 x 10-7M propranolol elicited delayed afterdepolarizations in eight of 10 preparations at a Ca++ concentration of 8.1 mM; nondrive-triggered action potentials were recorded from three of the preparations. These afterpotentials were completely suppressed by 5 x 10-7M prazosin or 10-6M phentolamine. In the presence of 5 x 10-7M propranolol, 10-5M phenylephrine prolonged action potential duration and this effect was suppressed by 5 x 10-7M prazosin. Methoxamine, at a concentration of 5 x 10-6M, was also observed to potentiate delayed afterdepolarizations in all of three preparations studied. These results demonstrate that α-adrenergic stimulation can induce afterpotentials in the presence of elevated Ca++ levels in cat hearts. Stimulation of α-adrenoceptors may be responsible for arrhythmias under Ca++-loaded conditions such as ischemia and coronary reperfusion.

Original languageEnglish
Pages (from-to)1074-1082
Number of pages9
JournalCirculation
Volume70
Issue number6
StatePublished - Dec 1 1984
Externally publishedYes

Fingerprint

Purkinje Fibers
Prazosin
Felidae
Phenylephrine
Propranolol
Adrenergic Agents
Action Potentials
Cats
Calcium
Methoxamine
Myocardial Reperfusion
Phentolamine
Adrenergic Receptors
Cardiac Arrhythmias
Ischemia

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by α-adrenergic stimulation in the presence of elevated calcium levels. / Kimura, S.; Cameron, J. S.; Kozlovskis, P. L.; Bassett, A. L.; Myerburg, Robert J.

In: Circulation, Vol. 70, No. 6, 01.12.1984, p. 1074-1082.

Research output: Contribution to journalArticle

@article{45738b27efbe46239eb18a935aba085f,
title = "Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by α-adrenergic stimulation in the presence of elevated calcium levels",
abstract = "We studied the ability of α-adrenergic stimulation to induce delayed afterdepolarizations and triggered activity in Purkinje fibers from cat hearts in the presence of an elevated Ca++ concentration. Delayed afterdepolarizations could not be induced at drive cycle lengths of 200 to 500 msec in the presence of extracellular Ca++ concentrations of 2.7 to 8.1 mM. However, the addition of 10-5M phenylephrine in the presence of 5 x 10-7M propranolol elicited delayed afterdepolarizations in eight of 10 preparations at a Ca++ concentration of 8.1 mM; nondrive-triggered action potentials were recorded from three of the preparations. These afterpotentials were completely suppressed by 5 x 10-7M prazosin or 10-6M phentolamine. In the presence of 5 x 10-7M propranolol, 10-5M phenylephrine prolonged action potential duration and this effect was suppressed by 5 x 10-7M prazosin. Methoxamine, at a concentration of 5 x 10-6M, was also observed to potentiate delayed afterdepolarizations in all of three preparations studied. These results demonstrate that α-adrenergic stimulation can induce afterpotentials in the presence of elevated Ca++ levels in cat hearts. Stimulation of α-adrenoceptors may be responsible for arrhythmias under Ca++-loaded conditions such as ischemia and coronary reperfusion.",
author = "S. Kimura and Cameron, {J. S.} and Kozlovskis, {P. L.} and Bassett, {A. L.} and Myerburg, {Robert J}",
year = "1984",
month = "12",
day = "1",
language = "English",
volume = "70",
pages = "1074--1082",
journal = "Circulation",
issn = "0009-7322",
publisher = "Lippincott Williams and Wilkins",
number = "6",

}

TY - JOUR

T1 - Delayed afterdepolarizations and triggered activity induced in feline Purkinje fibers by α-adrenergic stimulation in the presence of elevated calcium levels

AU - Kimura, S.

AU - Cameron, J. S.

AU - Kozlovskis, P. L.

AU - Bassett, A. L.

AU - Myerburg, Robert J

PY - 1984/12/1

Y1 - 1984/12/1

N2 - We studied the ability of α-adrenergic stimulation to induce delayed afterdepolarizations and triggered activity in Purkinje fibers from cat hearts in the presence of an elevated Ca++ concentration. Delayed afterdepolarizations could not be induced at drive cycle lengths of 200 to 500 msec in the presence of extracellular Ca++ concentrations of 2.7 to 8.1 mM. However, the addition of 10-5M phenylephrine in the presence of 5 x 10-7M propranolol elicited delayed afterdepolarizations in eight of 10 preparations at a Ca++ concentration of 8.1 mM; nondrive-triggered action potentials were recorded from three of the preparations. These afterpotentials were completely suppressed by 5 x 10-7M prazosin or 10-6M phentolamine. In the presence of 5 x 10-7M propranolol, 10-5M phenylephrine prolonged action potential duration and this effect was suppressed by 5 x 10-7M prazosin. Methoxamine, at a concentration of 5 x 10-6M, was also observed to potentiate delayed afterdepolarizations in all of three preparations studied. These results demonstrate that α-adrenergic stimulation can induce afterpotentials in the presence of elevated Ca++ levels in cat hearts. Stimulation of α-adrenoceptors may be responsible for arrhythmias under Ca++-loaded conditions such as ischemia and coronary reperfusion.

AB - We studied the ability of α-adrenergic stimulation to induce delayed afterdepolarizations and triggered activity in Purkinje fibers from cat hearts in the presence of an elevated Ca++ concentration. Delayed afterdepolarizations could not be induced at drive cycle lengths of 200 to 500 msec in the presence of extracellular Ca++ concentrations of 2.7 to 8.1 mM. However, the addition of 10-5M phenylephrine in the presence of 5 x 10-7M propranolol elicited delayed afterdepolarizations in eight of 10 preparations at a Ca++ concentration of 8.1 mM; nondrive-triggered action potentials were recorded from three of the preparations. These afterpotentials were completely suppressed by 5 x 10-7M prazosin or 10-6M phentolamine. In the presence of 5 x 10-7M propranolol, 10-5M phenylephrine prolonged action potential duration and this effect was suppressed by 5 x 10-7M prazosin. Methoxamine, at a concentration of 5 x 10-6M, was also observed to potentiate delayed afterdepolarizations in all of three preparations studied. These results demonstrate that α-adrenergic stimulation can induce afterpotentials in the presence of elevated Ca++ levels in cat hearts. Stimulation of α-adrenoceptors may be responsible for arrhythmias under Ca++-loaded conditions such as ischemia and coronary reperfusion.

UR - http://www.scopus.com/inward/record.url?scp=0021682528&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021682528&partnerID=8YFLogxK

M3 - Article

VL - 70

SP - 1074

EP - 1082

JO - Circulation

JF - Circulation

SN - 0009-7322

IS - 6

ER -