Linked Life Data

2847886

Source:http://linkedlifedata.com/resource/pubmed/id/2847886

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1989-1-12
pubmed:abstractText
We studied the effects of alpha-adrenergic receptor stimulation and calcium on automaticity of isolated canine Purkinje fibers during simulated ischemia and reperfusion. Ischemia included acidosis (pH 6.7), hypoxia (PO2 = 10-25 mm Hg), hyperkalemia (10 mM K+), and either normal or elevated [Ca2+]o (2.7 or 10.8 mM). Control automatic rate and maximum diastolic potential were 18 +/- 2 beats/min and -94 +/- 1 mV, respectively. Simulated ischemia led to depolarization (to -60 +/- 1 mV), cessation of normal automaticity, and in 21% of fibers, bursts of an abnormal automatic rhythm. Phenylephrine, 5 X 10(-8) M, increased the incidence of the automatic rhythm during ischemia to 44%; this effect was blocked by prazosin but not by propranolol. During reperfusion after simulated ischemia at 2.7 mM [Ca2+]o, automatic rhythm and maximum diastolic potential returned toward control values; after simulated ischemia at 10.8 mM [Ca2+]o, automatic rates were greater than those seen after normal Ca2+ ischemia and were associated with sustained membrane depolarization. Phenylephrine (5 X 10(-8) M) at 2.7 mM [Ca2+]o rapidly restored membrane potential during reperfusion, an effect that was blocked by prazosin. At 10.8 mM [Ca2+]o, phenylephrine also restored membrane potential during reperfusion and blunted the increase in reperfusion rate induced by high [Ca2+]o alone. These effects were blocked by propranolol but not by prazosin. Our results show that the effects of phenylephrine on automatic rhythms during simulated ischemia are blocked by alpha-adrenergic receptor antagonists and that rhythms occurring during reperfusion have alpha- and beta-adrenergic receptor components.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0009-7322
pubmed:author
pubmed:issnType
Print
pubmed:volume
78
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1495-502
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Alpha-adrenergic receptor stimulation during simulated ischemia and reperfusion in canine cardiac Purkinje fibers.
pubmed:affiliation
Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.