Automatic activity in depolarized guinea pig ventricular myocardium. Characteristics and mechanisms

Circulation Research
S Imanishi, B Surawicz

Abstract

Membrane potential was changed uniformly in segments, 0.7-1.0 mm long, of guinea pig papillary muscles excised from the right ventricle by using extracellular polarizing current pulses applied across two electrically insulated cf preparations superfused with Tyrode's solution at maximum diastolic membrane potentials ranging from-35.2+/-7.5 (threshold) to +4.0+/-9.2 mV. The average maximum dV/dt of RAD ranged from 17.1 to 18.0 V/sec within a membrane potential range of -40 to +20 mV. Raising extracellular Ca2+ concentration [Ca2+]0 from 1.8 to 6.8 mM, or application of isoproterenol (10(-6)g/ml) enhanced the rate of RAD, but lowering [Ca2+]0 to 0.4 mM or exposure to MnCl2 (6 mM) abolished RAD. RAD were enhanced by lowering extracellular K+ concentration [K+]0 from 5.4 to 1.5 mM. RAD were suppressed in 40% of fibers by raising [K+]0 to 15.4 mM, and in all fibers by raising [K+]0 to 40.4 mM. This suppression was due to increased [K+]0 and not to K-induced depolarization because it persisted when membrane potential was held by means of a conditioning hyperpolarizing puled gradually after maximum repolarization. These observations suggest that the development of RAD in depolarized myocardium is associated with a time-dependent decre...Continue Reading

References

Jan 1, 1971·Naunyn-Schmiedebergs Archiv Für Pharmakologie·H Antoni
Aug 1, 1974·The Journal of Physiology·L S Gettes, H Reuter
Jan 11, 1974·Pflügers Archiv : European journal of physiology·R S Aronson, P F Cranefield
May 6, 1974·Pflügers Archiv : European journal of physiology·R Ochi, H Nishiye
Feb 1, 1972·The Journal of General Physiology·P F CranefieldB F Hoffman
Jan 1, 1972·Pflügers Archiv : European journal of physiology·W New, W Trautwein
Jan 1, 1968·Pflügers Archiv für die gesamte Physiologie des Menschen und der Tiere·M Morad, W Trautwein
Aug 15, 1966·The Japanese Journal of Physiology·A Kamiyama, K Matsuda
Aug 1, 1971·The Japanese Journal of Physiology·S Imanishi
Jan 1, 1970·Pflügers Archiv : European journal of physiology·R Ochi
Nov 1, 1970·The Journal of Physiology·S Weidmann
Mar 1, 1970·The Journal of Physiology·G W Beeler, H Reuter
Dec 1, 1967·Circulation Research·J A Reid, H H Hecht
Apr 1, 1965·The American Journal of Physiology·M VASSALLE

❮ Previous
Next ❯

Citations

Jan 1, 1981·Naunyn-Schmiedeberg's Archives of Pharmacology·M Hiraoka, Y Okamoto
Jan 1, 1989·Pflügers Archiv : European journal of physiology·H C Lee, W T Clusin
Oct 1, 1979·Pflügers Archiv : European journal of physiology·A J Pappano, E E Carmeliet
Apr 1, 1996·Journal of the American College of Cardiology·T MiyazakiS Ogawa
Aug 29, 1996·The American Journal of Cardiology·P A Boyden
Jul 1, 1985·Journal of the American College of Cardiology·J Kupersmith, P Hoff
Jun 1, 1985·Journal of the American College of Cardiology·B Surawicz
Dec 1, 1988·Journal of the American College of Cardiology·J HasegawaH Mashiba
Jun 29, 1999·British Journal of Pharmacology·T NakajimaH Hazama
Nov 1, 1986·The Journal of Clinical Investigation·E MarbanW G Wier
Mar 3, 1980·Klinische Wochenschrift·C Naumann d'AlnoncourtD Durrer
Oct 2, 1978·Life Sciences·B G Katzung
Jan 1, 1984·Annals of the New York Academy of Sciences·A L Wit
Aug 13, 2004·Pacing and Clinical Electrophysiology : PACE·Sanjay DixitFrancis E Marchlinski
Mar 19, 2004·Journal of Cardiovascular Electrophysiology·Borys Surawicz
Aug 6, 2014·Journal of Cellular and Molecular Medicine·Dan ShiYi-Han Chen
Oct 1, 1983·American Heart Journal·A L Wit, M R Rosen
Apr 11, 1992·American Heart Journal·A O Grant
Jul 1, 1982·Pacing and Clinical Electrophysiology : PACE·B Lüderitz
Nov 1, 1984·Pacing and Clinical Electrophysiology : PACE·G MottéJ M Davy
Dec 7, 1990·Journal of Theoretical Biology·A Vinet, F A Roberge
Apr 1, 1985·The American Journal of Cardiology·T MiyazakiY Nakamura
Oct 1, 1978·The American Journal of Cardiology·F Marchi
Apr 9, 2009·Progress in Biophysics and Molecular Biology·Morten GrunnetSøren-Peter Olesen
Jan 1, 1983·Journal of the American College of Cardiology·L S Gettes
Oct 1, 1983·Journal of Molecular and Cellular Cardiology·A MugelliA Giotti
Jul 1, 1981·Circulation Research·B F Hoffman, M R Rosen
Jan 3, 2001·Journal of Applied Physiology·M P NashD J Paterson

❮ Previous
Next ❯

Related Concepts

Related Feeds

Cardiac Electrophysiology

Cardiac electrophysiology is the study of electrical activities of the heart and includes the assessment, diagnosis, and treatment of cardiac events. Find the latest research on cardiac electrophysiology here.