Comparison of the cardiac electrophysiological effects between doxazosin and bunazosin

Journal of Biomedical Science
An-Sheng LeeMing-Jai Su

Abstract

In Langendorff-perfused adult rat heart with constant pressure at 80 mmHg, we found doxazosin, an alpha(1) adrenoceptor blocker, at 10 muM prolonged PR interval and induced occasional arrhythmia followed by complete inhibition of the sinus rhythm, whereas bunazosin, another alpha(1)-blocker, at same concentration did not. The results of voltage-clamp study showed that, at the concentration of 10 muM, doxazosin inhibited I (Na), I ( (Ca,L) ), I (to), and Iss without changing I (k1) but bunazosin only inhibited I ( (Ca,L) ) about 30%. Doxazosin also caused markedly negative shift of the I (Na) inactivation curve. In current-clamp study, doxazosin prolonged action potential duration in association with the decreased action potential amplitude and upstroke velocity, whereas bunazosin did not. We hypothesize that doxazosin-induced arrhythmia may result from the heterogeneous or different level of I ( (Ca,L) ) blockade of AV nodal tissue. In conclusion, the present study suggests that bunazosin is safer than doxazosin for long-term treatment in view of electrophysiological effect. However, the underlying mechanism of doxazosin induced nodal arrhythmia is still needed to be determined.

References

Nov 14, 1977·Biochimica Et Biophysica Acta·L M Hondeghem, B G Katzung
Jul 1, 1988·American Heart Journal·N M Kaplan
Feb 1, 1984·Circulation Research·I R JosephsonA M Brown
Sep 1, 1981·The Journal of Physiology·A M BrownT Powell
Aug 1, 1994·Pacing and Clinical Electrophysiology : PACE·R J SungH Chun
Sep 1, 1993·European Heart Journal·S G PrioriP J Schwartz
Jan 1, 1993·Physiological Reviews·H IrisawaW Giles
Feb 1, 1997·Pflügers Archiv : European journal of physiology·J GuoA Noma
Jan 24, 2002·Nature·Eduardo Marbán
Sep 25, 2003·Metabolism: Clinical and Experimental·C Hamish CourtneyPatrick M Bell
Dec 13, 2003·Journal of Pharmacological and Toxicological Methods·R L HamlinT Arnold
Oct 14, 2006·The Journal of Physiology·Guy Salama, Barry London
Oct 31, 2006·American Heart Journal·Richard Shannon, Mohammad Chaudhry
Nov 23, 2007·European Journal of Pharmacology·An-Sheng LeeMing-Jai Su

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