De. Benavides-haro et Ja. Sanchez-chapula, Chloroquine blocks the background potassium current in guinea pig atrial myocytes, N-S ARCH PH, 361(3), 2000, pp. 311-318
In this study we examined the effects of chloroquine on the muscarinic pota
ssium current, IK-ACh, and the inward rectifying potassium current, I-K1. W
e utilized three ways to induce IK-ACh: activating the M-2-muscarinic recep
tors with carbachol? activating the purinergic A(1)-receptors with adenosin
e and directly activating the G(K)-protein coupled with these receptors in
an irreversible way with GTP gamma S. In experiments using the whole-cell c
onfiguration of the patch-clamp technique, we found that chloroquine, indep
endently from the manner of activation of IK-ACh, was able to block this cu
rrent with similar potency. These results strongly suggest that chloroquine
may be acting directly on the muscarinic potassium channel. Chloroquine al
so blocked I-K1 with similar potency, in both guinea pig atrial and ventric
ular myocytes.