Comparative study of the block of Vmax by aprindine and quinidine in the guinea-pig heart muscle.
The depression of Vmax of the action potential in guinea-pig ventricular muscle by aprindine and quanidine was compared. Aprindine caused a more pronounced rate-dependent block (Kd = 10(-6) M at 3.3 Hz) than did quinidine (Kd = 1.6 X 10(-5) M at 3.3 Hz). Aprindine shifted the relationship between Vmax and resting potential to a more negative potential (mean 9.2 mV: 10 microM) than did quinidine (mean 5.7 mV: 10 microM). In addition, aprindine caused a more pronounced resting block (Kd = 1.3 X 10(-5) M) than quinidine (Kd = 8.6 X 10(-5) M). It is concluded that aprindine has a higher affinity for activated and/or inactivated and resting state channels than quinidine, making channels unavailable for conduction upon activation.
Hisatome
I
I
1st Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan.
Miyamoto
J
J
Hasegawa
J
J
Kotake
H
H
Mashiba
H
H
Sato
R
R
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001073:Aprindine / Q000494:pharmacology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007192:Indenes / Q000494:pharmacology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D011802:Quinidine / Q000494:pharmacology*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism
D007192:Indenes; D015222:Sodium Channels; D001073:Aprindine; D011802:Quinidine