Objective    To study the effect of angiotensinⅡ(AngⅡ) and telmisartan on transient outward potassium and calcium current in atrial myocytes of Sprague-Dawley (SD) rats.     Methods     Atrial myocytes were isolated from SD rats with the enzymatic dissociation method. Effect of AngⅡ

telmisartan and conbined AngⅡand telmisartan on transient outward potassium and calcium current in atrial myocytes of SD rats was observed with the whole cell patch-clamp recording technique.     Results    AngⅡ(0.1 μmol/L)

telmisartan (0.01 μmol/L)

and combined AngⅡ and telmisartan inhibited the outward potassium current. The peak outward potassium current density was 22.48±2.75 vs 15.71±2.06 pA/pF

24.16±2.36 vs 16.15±1.82 pA/pF

and 24.41±2.27  vs 21.35±1.46 pA/pF

respectively (P0.05)

in AngⅡgroup

telmisartan group

and combined AngⅡand telmisartan group. AngⅡ(0.1 μmol/L) significantly increased the peak calcium current density in atrial myocytes of rats (-4.51±0.38 vs -5.16±0.29 pA/pF

P0.01). Telmisartan (0.01 μmol/L) had no significant effect on the peak calcium current density in atrial myocytes of rats (-4.35±0.27 vs -4.29±0.34 pA/pF

P0.05). However

it could antagonize the effect of AngⅡon the peak calcium current density in combined AngⅡ and telmisartan group（-4.08±0.28 vs -4.20±0.31 pA/pF

P0.05）.     Conclusion    AngⅡand telmisartan can exert their direct electrophysiological effects on atrial myocytes of rats

while telmisartan can antagonize the effect of AngⅡon the peak calcium current density at angiotensin receptor level.