Anti-cholinergic effect of verapamil on the muscarinic acetylcholine receptor-gated K+ channel in isolated guinea-pig atrial myocytes

2004 ◽  
Vol 339-339 (1-2) ◽  
pp. 244-246 ◽  
Author(s):  
Hiroyuki Ito ◽  
Reiko Takikawa ◽  
Yoshihisa Kurachi ◽  
Tsuneaki Sugimoto
Keyword(s):  
Guinea Pig ◽  
Acetylcholine Receptor ◽  
Muscarinic Acetylcholine Receptor ◽  
K Channel ◽  
Atrial Myocytes ◽  
Muscarinic Acetylcholine ◽  
Cholinergic Effect

Molecular mechanism of doxorubicin-induced anticholinergic effect in guinea-pig atria

2000 ◽  
Vol 78 (6) ◽  
pp. 483-489 ◽  
Author(s):  
Yukio Hara ◽  
Kyosuke Temma ◽  
Zin Sekiya ◽  
Akihito Chugun ◽  
Hiroshi Kondo
Keyword(s):  
Guinea Pig ◽  
Action Potential ◽  
Acetylcholine Receptor ◽  
Action Potential Duration ◽  
Molecular Mechanisms ◽  
Muscarinic Acetylcholine Receptor ◽  
Anticholinergic Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Muscarinic Acetylcholine

The molecular mechanisms of anticholinergic actions of doxorubicin were examined by electrophysiological methods in atria and myocytes isolated from guinea-pig heart. A direct anticholinergic action of doxorubicin was confirmed with antagonistic action on carbachol-induced negative inotropic effect in atria. Both carbachol and adenosine produced shortening of action potential duration in atria measured by a microelectrode method. Doxorubicin (10-100 µM) inhibited the carbachol-induced action potential shortening in a concentration-dependent manner. However, doxorubicin did not antagonize the shortening elicited by adenosine. The whole-cell voltage clamp technique was performed to induce the muscarinic acetylcholine-receptor-operated K+ current (IK.ACh) in atrial myocytes loaded with GTP or GTPgammaS, a nonhydrolysable analogue of GTP. Doxorubicin (1-100 µM) suppressed carbachol-induced IK.ACh in a concentration-dependent manner (IC50 = 5.6 µM). In contrast, doxorubicin (10 and 100 µM) suppressed neither adenosine-induced IK.ACh nor GTPgammaS-induced IK.ACh. These results indicate that doxorubicin produces a direct anticholinergic effect through the muscarinic receptors in atrial myocytes.Key words: action potential duration, anticholinergic action, atrial cell, doxorubicin, the muscarinic acetylcholine-receptor-operated K+ current.

Sign in / Sign up

Export Citation Format

Share Document