Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes.
OBJECTIVE
To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na+/H+ exchanger inhibitor--amiloride.


METHODS
Single ventricular cells were isolated using a double-enzyme method. Effects of amiloride on voltage-dependent potassium and calcium currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques.


RESULTS
Exposure to amiloride (10 -100 micromol x L(-1)), the L-type and T-type calcium currents were depressed. Amiloride resulted in a concentration-dependent inhibition of peak (Ca,L), But amiloride did not change the shape of their I - V curves. It only decreased the amplitudes of the currents of the two types. When myocytes were incubated with 100 micromol x L(-1) amiloride, I(Kr) was slightly depressed and I(Ks) did not change. Amiloride (1 - 100 micromol x L(-10) depressed I(K1) in a concentration-dependent manner.


CONCLUSIONS
Amiloride depressed potassium and calcium currents, which may give support to its uses in some diseases of the cardiovascular system.
Cheng
Lan
L
Department of Pharmacology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China. chenglan1@hotmail.com
Wang
Fang
F
Zhou
Hong-Yi
HY
Yao
Wei-Xing
WX
Xia
Guo-Jin
GJ
Jiang
Ming-Xing
MX
D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D020747:Calcium Channels, T-Type / Q000187:drug effects*; D002469:Cell Separation; D005260:Female; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects*; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors
D000889:Anti-Arrhythmia Agents; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D017923:Sodium-Hydrogen Exchangers; C069139:growth factor-activatable Na-H exchanger NHE-1; D000584:Amiloride