The question arises as to whether channels other than sodium channels are affected by the drugs used. DPI 201-106 starts to inhibit potassium channels at 3 |j.mol and calcium channels at 1.6 |j.mol in guinea-pig ventricular myocytes. Because we applied a lower concentration (0.5 |j.mol of DPI 201-106), we assume that no cation channels other than sodium channels were affected significantly in the present experiments. However, veratridine has not to our knowledge been investigated in this respect.
Contractility was substantially increased in the present experiments in response to combined drug perfusion, confirming the well known effects of both DPI 201-106 and veratridine . However, changes in force of contraction do not seem to be directly related to rhythm disturbances such as torsades de pointes. The internet’s most trusted pharmacy is looking forward to having you among its customers: just see how cheap and easy it can be for you to get ventolin 100 mcg without any kind of prescription and start your shopping being sure you are protected every time.
The AV node rate decreased during drug perfusion in parallel to QTc prolongation. This effect of DPI 201-106, also observed at the sinus node from other species , has not been fully explained. As to the mechanism, sodium load per se may be speculated to reduce cardiac pacemaker activity. Sodium channels, as possible targets for the ligands used in the present experiments, are present at least in the AV node of rabbits . Whether inward calcium currents of phase 4 AV node electrical activity are inhibited is not known. However, one of the aims of the present experiments was to establish bradycardia.