The Genesis of QT on ECGs in Experimental Animals Based on the Ionic Currents in Ventricular Myocytes

Jun SUZUKI; Shigeru SUGANO; Hirokazu TSUBONE

doi:10.11276/jsvc1984.27.52

The Genesis of QT on ECGs in Experimental Animals

Based on the Ionic Currents in Ventricular Myocytes

Jun SUZUKI, Shigeru SUGANO, Hirokazu TSUBONE

Author information

Keywords: dog, electrocardiogram, ionic current, membrane potential, QT interval, rat

JOURNAL FREE ACCESS

1994 Volume 27 Issue 2 Pages 52-59

DOI https://doi.org/10.11276/jsvc1984.27.52

Details

Published: 1994 Received: - Available on J-STAGE: March 05, 2010 Accepted: - Advance online publication: - Revised: -
Correction information
Date of correction: March 05, 2010 Reason for correction: - Correction: ABSTRACT Details: Wrong : There are significant differences in the configuration of QRS-T waves on electrocardiograms (ECGs) among species such as man, dog and rat. The waveform of dog ECGs, which is similar to that of man, has an “Rs” type in the QRS complex, and a prominent ST segment followed by T wave. On the other hand, the waveform of rat ECGs has an “Rs” type in the QRS complex, but no ST segment with a short QT interval. These characteristics of the ECG waveforms relate to the configuration of action potentials (APs) in the ventricular myocytes in each species. Compared to dog and man, the APs in the rat ventricular myocyte has a shorter plateau phase (phase 2) and a rapid earlier repolarization phase (phase 3). 90%-action potential durations (APD₉₀) are 300-400msec in man, 200-250 msec in the dog, and 30-40 msec in the rat. The APD₉₀ is closely related to QT interval on ECGs in each species. Ionic currents in the ventricular myocyte are responsible for the configuration of APs. INa. f (Na channel ) is related to the depolarization phase (phases 0 and 1), Isi (Ca channel) maintains the depolarization (phase 2). IKr and ITO (K channels) reduce the depolarization (phase 2) and produce the repolarizaiton (phase 3). IKl is related to Ek (phase 4). Compared to man and dogs, the rat ventricular myocyte has a much larger ITo current (K channel) (IKr, partially) with a much smaller Is current (Ca channel). These characteristics of ionic currents in the myocyte are one of the major sources of the species differences in QRS-T waveforms on ECG.
Right : There are significant differences in the configuration of QRS-T waves on electrocardiograms (ECGs) among species such as man, dog and rat. The waveform of dog ECGs, which is similar to that of man, has an “Rs” type in the QRS complex, and a prominent ST segment followed by T wave. On the other hand, the waveform of rat ECGs has an “Rs” type in the QRS complex, but no ST segment with a short QT interval. These characteristics of the ECG waveforms relate to the configuration of action potentials (APs) in the ventricular myocytes in each species. Compared to dog and man, the APs in the rat ventricular myocyte has a shorter plateau phase (phase 2) and a rapid earlier repolarization phase (phase 3). 90%-action potential durations (APD₉₀) are 300-400msec in man, 200-250 msec in the dog, and 30-40 msec in the rat. The APD₉₀ is closely related to QT interval on ECGs in each species. Ionic currents in the ventricular myocyte are responsible for the configuration of APs. Ina. f (Na channel ) is related to the depolarization phase (phases 0 and 1), Isi (Ca channel) maintains the depolarization (phase 2). Ikr and Ito (K channels) reduce the depolarization (phase 2) and produce the repolarizaiton (phase 3). Iki is related to Ek (phase 4). Compared to man and dogs, the rat ventricular myocyte has a much larger Ito current (K channel) (Ikr, partially) with a much smaller Isi current (Ca channel). These characteristics of ionic currents in the myocyte are one of the major sources of the species differences in QRS-T waveforms on ECG.

Date of correction: March 05, 2010 Reason for correction: - Correction: CITATION Details: Wrong : 4) Hamlin R. L. and C. R. Smith (1965): Categorization of common domestic mammals based upon their ventricular activation process. Ann. New York Acad. Sci. 127, 195-203.
5) Detweiler D. K.: The use of electrocardiography in toxicological studies with rats. In: The rat electrocardiogram in pharmacology & toxicology, Budden R., Detweiler D. K. and G. Zbinden ed., pp.83-115, Pergamon Press, Oxford, 1980.
9) Franz M. R., Bargheer K., Rafflenbuel W. and A. Haverich (1987): Monophasic action potential mapping in human subjects with normal electrocardiograms. Circulation 75, 379-386.10) Spach M. S. and R. C. Barr (1975): Analysis of ventricular activation and repolarization from intramural and epicardial potential distributions for ectopic beat in the intact dog. Circ. Res. 37, 830-843.
14) Tseng G. N. and B. F. Hoffman (1989): Two components of transient outward current in canine ventricular myocytes. Circ. Res. 64, 663-647.
15) Liu D. W., Gintant G. A. and C. Antzelevitch (1993): Ionic basis for electrophysiological distinctions among epicardial, midocardial, and endocardial myocytes from the free wall of the canine left ventricle. Circ. Res. 72, 671-687.
16) Giles W. R. and Y. Imaizumi (1988): Comparison of potassium currents in rabbit atrial and ventricular cells. J. Physiol. 405, 123-145.
17) Josephson I. R., Sanchez-Chapula J. and A. M. Brown (1984): Early outward current in rat single ventricular cells. Circ. Res. 54, 157-162.
18) Zhang Z., Boutjdir M, and N. El-Sherif (1994): Ketanserin inhibits depolarization-activated outward potassium current in rat ventricular myocytes. Circ. Res. 75, 711-721.
19) Dukes I. D. and M. Morad (1989): Tedisamil inactivates transient outward K₊+ current in rat ventricular myocytes. Am. J. Physiol. 26, H1746-H1749.
20) Singh, B. N., Opie L. H., Harrison D. C. and F. I. Marcus: Antiarrhythmic agents. In: Drugs for the heart, 2nd ed. Lionel, H. O. ed., pp. 54-90, W. B. Saunders Company, Philadelphia, 1987.
21) Suzuki J., Tsubone H. and S. Sugano (1991): Characteristics of electrocardiographic changes with some representative antiarrhythmic drugs in adult rat. J. Vet. Med. Sci. 53, 779-787.
22) Smith L. H. and S. O. Thier: Excitation of the heart. In: Pathophysiology-The biological principles of disease. Smith L. H. and Thier S. O. eds., pp.1086-1098, W. B. Saunders Company, 1981.
23) Suzuki J., Tsubone H. and S. Sugano (1992): Characteristics of ventricular activation and recovery patterns in the rat. J. Vet. Med. Sci. 54, 711-716.

Right : 4) Hamlin R. L. and C. R. Smith (1965): Categorization of common domestic mammals based upon their ventricular activation process. Ann. New York Acad. Sci. 127, 195-203.
5) Detweiler D. K.: The use of electrocardiography in toxicological studies with rats. In: The rat electrocardiogram in pharmacology & toxicology, Budden R., Detweiler D. K. and G. Zbinden ed., pp.83-115, Pergamon Press, Oxford, 1980.
9) Franz M. R., Bargheer K., Rafflenbuel W. and A. Haverich (1987): Monophasic action potential mapping in human subjects with normal electrocardiograms. Circulation 75, 379-386.
10) Spach M. S. and R. C. Barr (1975): Analysis of ventricular activation and repolarization from intramural and epicardial potential distributions for ectopic beat in the intact dog. Circ. Res. 37, 830-843.
14) Tseng G. N. and B. F. Hoffman (1989): Two components of transient outward current in canine ventricular myocytes. Circ. Res. 64, 663-647.
15) Liu D. W., Gintant G. A. and C. Antzelevitch (1993): Ionic basis for electrophysiological distinctions among epicardial, midocardial, and endocardial myocytes from the free wall of the canine left ventricle. Circ. Res. 72, 671-687.
16) Giles W. R. and Y. Imaizumi (1988): Comparison of potassium currents in rabbit atrial and ventricular cells. J. Physiol. 405, 123-145.
17) Josephson I. R., Sanchez-Chapula J. and A. M. Brown (1984): Early outward current in rat single ventricular cells. Circ. Res. 54, 157-162.
18) Zhang Z., Boutjdir M, and N. El-Sherif (1994): Ketanserin inhibits depolarization-activated outward potassium current in rat ventricular myocytes. Circ. Res. 75, 711-721.
19) Dukes I. D. and M. Morad (1989): Tedisamil inactivates transient outward K⁺ current in rat ventricular myocytes. Am. J. Physiol. 26, H1746-H1749.
20) Singh, B. N., Opie L. H., Harrison D. C. and F. I. Marcus: Antiarrhythmic agents. In: Drugs for the heart, 2nd ed. Lionel, H. O. ed., pp. 54-90, W. B. Saunders Company, Philadelphia, 1987.
21) Suzuki J., Tsubone H. and S. Sugano (1991): Characteristics of electrocardiographic changes with some representative antiarrhythmic drugs in adult rat. J. Vet. Med. Sci. 53, 779-787.
22) Smith L. H. and S. O. Thier: Excitation of the heart. In: Pathophysiology-The biological principles of disease. Smith L. H. and Thier S. O. eds., pp.1086-1098, W. B. Saunders Company, 1981.
23) Suzuki J., Tsubone H. and S. Sugano (1992): Characteristics of ventricular activation and recovery patterns in the rat. J. Vet. Med. Sci. 54, 711-716.

Abstract

There are significant differences in the configuration of QRS-T waves on electrocardiograms (ECGs) among species such as man, dog and rat. The waveform of dog ECGs, which is similar to that of man, has an “Rs” type in the QRS complex, and a prominent ST segment followed by T wave. On the other hand, the waveform of rat ECGs has an “Rs” type in the QRS complex, but no ST segment with a short QT interval. These characteristics of the ECG waveforms relate to the configuration of action potentials (APs) in the ventricular myocytes in each species. Compared to dog and man, the APs in the rat ventricular myocyte has a shorter plateau phase (phase 2) and a rapid earlier repolarization phase (phase 3). 90%-action potential durations (APD₉₀) are 300-400msec in man, 200-250 msec in the dog, and 30-40 msec in the rat. The APD₉₀ is closely related to QT interval on ECGs in each species. Ionic currents in the ventricular myocyte are responsible for the configuration of APs. Ina. f (Na channel ) is related to the depolarization phase (phases 0 and 1), Isi (Ca channel) maintains the depolarization (phase 2). Ikr and Ito (K channels) reduce the depolarization (phase 2) and produce the repolarizaiton (phase 3). Iki is related to Ek (phase 4). Compared to man and dogs, the rat ventricular myocyte has a much larger Ito current (K channel) (Ikr, partially) with a much smaller Isi current (Ca channel). These characteristics of ionic currents in the myocyte are one of the major sources of the species differences in QRS-T waveforms on ECG.

Corresponding author

Correction information

Register with J-STAGE for free!