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Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle.

Publication ,  Journal Article
Browning, DJ; Guarnieri, T; Strauss, HC
Published in: J Clin Invest
October 1981

The relationship between the positive inotropic and toxic effects of cardiac glycosides and their effects on intracellular ionic composition is incompletely defined. We measured intracellular potassium activity (alpha ik), extracellular potassium activity (alpha ek), resting potential, action potential duration, and contractile force at 32 degrees C in paired papillary muscles from feline right ventricles exposed to ouabain. Muscles used for electrophysiological measurements were quiescent except for isolated stimulation to confirm impalement and record action potential duration. Muscles used for contractile force measurements were quiescent except for 4-min periods when force was measured at a cycle length of 1,400 ms. Muscle length was adjusted to achieve 50% of maximal tension at this cycle length before each experiment. In four experiments, alpha ik and contractile force were measured in the same muscle. Alpha iK was measured with single and double-barrel K-sensitive electrodes. At 10 nM ouabain, action potential duration is prolonged. Among the concentrations tested, the threshold for a clear positive inotropic effect is 0.1 microM ouabain. The threshold for decrease in alpha iK, increase in alpha eK, and decrease in membrane potential is 1 microM, at which concentration toxic signs develop, including arrhythmias, aftercontractions, and alteration in the staircase response of contractile force to repetitive stimulation. Ouabain need not change alpha iK to effect positive inotropy in ventricular muscle, a relationship different from that reported between [K]i (intracellular potassium concentration) and positive inotropy. Higher ouabain concentrations, which others have shown to clearly inhibit active Na and K transport, are shown to upset intracellular potassium activity homeostasis and to consistently produce toxicity.

Duke Scholars

Published In

J Clin Invest

DOI

ISSN

0021-9738

Publication Date

October 1981

Volume

68

Issue

4

Start / End Page

942 / 956

Location

United States

Related Subject Headings

  • Time Factors
  • Potassium
  • Ouabain
  • Myocardium
  • Myocardial Contraction
  • Membrane Potentials
  • In Vitro Techniques
  • Immunology
  • Heart
  • Dose-Response Relationship, Drug
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Browning, D. J., Guarnieri, T., & Strauss, H. C. (1981). Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle. J Clin Invest, 68(4), 942–956. https://doi.org/10.1172/jci110349
Browning, D. J., T. Guarnieri, and H. C. Strauss. “Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle.J Clin Invest 68, no. 4 (October 1981): 942–56. https://doi.org/10.1172/jci110349.
Browning DJ, Guarnieri T, Strauss HC. Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle. J Clin Invest. 1981 Oct;68(4):942–56.
Browning, D. J., et al. “Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle.J Clin Invest, vol. 68, no. 4, Oct. 1981, pp. 942–56. Pubmed, doi:10.1172/jci110349.
Browning DJ, Guarnieri T, Strauss HC. Ouabain effects on intracellular potassium activity and contractile force in cat papillary muscle. J Clin Invest. 1981 Oct;68(4):942–956.

Published In

J Clin Invest

DOI

ISSN

0021-9738

Publication Date

October 1981

Volume

68

Issue

4

Start / End Page

942 / 956

Location

United States

Related Subject Headings

  • Time Factors
  • Potassium
  • Ouabain
  • Myocardium
  • Myocardial Contraction
  • Membrane Potentials
  • In Vitro Techniques
  • Immunology
  • Heart
  • Dose-Response Relationship, Drug