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I need the help of some expert in this:
1. class I block Na+ diastolic currents, I see in FA, but what kind of diastolic currents exist that put Na into the cell? I can only see the Na/K pump, and the Na/Ca antiport
2. Where does IA class act that prolong QT interval and AP potential? during repolarization (phase 3) only K+ channels are open so how this affect this part?
3. If IB shortens AP wouldn't it be expected to shorten QT interval as it acts the reverse way of IA?
4. how do b-blockers suppress the slope of phase 4 in SA node since it is conducted by If, the type of Na channels that determine automaticity? is it because they decrease Ca influx?
thanks in advance
1. class I block Na+ diastolic currents, I see in FA, but what kind of diastolic currents exist that put Na into the cell? I can only see the Na/K pump, and the Na/Ca antiport
2. Where does IA class act that prolong QT interval and AP potential? during repolarization (phase 3) only K+ channels are open so how this affect this part?
3. If IB shortens AP wouldn't it be expected to shorten QT interval as it acts the reverse way of IA?
4. how do b-blockers suppress the slope of phase 4 in SA node since it is conducted by If, the type of Na channels that determine automaticity? is it because they decrease Ca influx?
thanks in advance
