The acute electrophysiological effects of amiodarone on normal and hypertrophied rat myocytes / 中华心血管病杂志

ABSTRACT

<p><b>OBJECTIVE</b>The aim of the present study was to investigate the acute action of amiodarone (AM) on the inward currents I(Na), I(Ca-L) and outward currents I(k), I(k1), I(to) in hypertrophied and normal rat ventricular myocytes.</p><p><b>METHODS</b>The pressure overload hypertrophy rat model was established by partial ligation of ascending aorta for 4 weeks. Ventricular myocytes were exposed to 0.01, 0.1, 1, 10 and 50 micromol/L AM and whole cell patch clamp technique was used to study the acute effects of AM on the inward currents I(Na), I(Ca-L) and outward currents I(k), I(k1), I(to).</p><p><b>RESULTS</b>(1) Compared with the normal ventricular myocytes, the current density of I(k), I(ks), I(to) and I(k1) were all decreased in hypertrophied myocytes, but I(Na) and I(Ca-L) remained unchanged. (2) I(Ca-L) was blocked by 59.0% +/- 4.4% in normal myocytes but only blocked by 16.7% +/- 8.0% in hypertrophied myocytes after 50 micromol/L AM application; IC(50) of I(Na) were 9.2 micromol/L and 5.9 micromol/L in normal and in hypertrophied myocytes, respectively; I(to) was blocked by 55.9% +/- 5.5% in normal myocytes and 23.0% +/- 2.8% in hypertrophied myocytes after 50 micromol/L AM application. I(k1) was not affected by AM in both normal and hypertrophied myocytes; I(ks) was blocked by 21.6% +/- 5.6% in normal myocytes and 42.7% +/- 9.2% in hypertrophied myocytes after 10 micromol/L AM application.</p><p><b>CONCLUSION</b>Our results show that the sensitivity of hypertrophied myocytes to AM on I(Na), I(ks) were higher than that of normal myocytes, while the sensitivity on I(Ca-L), I(k1), I(to) were lower than that of normal myocytes favoring the use of AM on hypertrophied myocardium for antiarrhythmic therapy.</p>