Active and passive electrical properties of isolated canine cardiac Purkinje fibers under conditions simulating ischaemia: Effect of diltiazem

P. P. Nanasi, T. K. Knilans, A. Varro, Anne M Murphy, A. Fujiki, A. Schwartz, D. A. Lathrop

Research output: Contribution to journalArticle

Abstract

The effect of a calcium channel blocker diltiazem on the electrical properties of canine Purkinje fibers superfused in a milieu similar to that occurring in acute myocardial ischaemia was studied. Action potential parameters, passive electrical properties, and conduction velocity were measured using conventional microelectrode techniques. Superfusion with glucose-free Tyrode's solution containing 9 mM K+, gassed with 100% N2 at pH = 6.5 ('ischemic solution') significantly reduced the maximal diastolic potential, action potential duration, maximal upstroke velocity, conduction velocity and length constant, while input resistance and longitudinal resistance were elevated and membrane resistance remained unchanged. Diltiazem (1 μM) alone reduced only the action potential duration, while all other parameters were unaffected. Pretreatment with diltiazem did not fully prevent the effects of ischemic superfusion; however, the ischaemia-induced decrease in length constant was not significant in the presence of diltiazem. In addition, the increase in longitudinal resistance during ischaemia was significantly reduced following diltiazem pretreatment. This decrease in longitudinal resistance may contribute to the improvement of ischaemia-induced conduction delay observed in intact animals and may be related to a reduction of ischaemia-induced increase in intracellular free Ca2+.

Original languageEnglish (US)
Pages (from-to)52-56
Number of pages5
JournalPharmacology and Toxicology
Volume71
Issue number1
StatePublished - 1992
Externally publishedYes

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Purkinje Fibers
Diltiazem
Canidae
Electric properties
Ischemia
Fibers
Action Potentials
Microelectrodes
Calcium Channel Blockers
Myocardial Ischemia
Animals
Membranes
Glucose

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Pharmacology
  • Toxicology

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Active and passive electrical properties of isolated canine cardiac Purkinje fibers under conditions simulating ischaemia : Effect of diltiazem. / Nanasi, P. P.; Knilans, T. K.; Varro, A.; Murphy, Anne M; Fujiki, A.; Schwartz, A.; Lathrop, D. A.

In: Pharmacology and Toxicology, Vol. 71, No. 1, 1992, p. 52-56.

Research output: Contribution to journalArticle

Nanasi, P. P. ; Knilans, T. K. ; Varro, A. ; Murphy, Anne M ; Fujiki, A. ; Schwartz, A. ; Lathrop, D. A. / Active and passive electrical properties of isolated canine cardiac Purkinje fibers under conditions simulating ischaemia : Effect of diltiazem. In: Pharmacology and Toxicology. 1992 ; Vol. 71, No. 1. pp. 52-56.
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