Calcium Channel blockers, and DHP

[anbuitachi]

Bit confused about calcium channel blockers..

Verapamil and diltiazem are NON DHP channel blockers that target mainly the heart, blocking L type ca channels. While Nifedipine and amlodipine are DHP, and mainly vasodilates..

But in the heart, in phase 0, L type dihydropyridine Ca channels open to depolarize the cell. Are these the channels that verapamil is blocking? Because the channel name says dihydropyridine.. while verapamil is a non dhp Ca channel blocker.. [while a DHP channel blocker like Nifedipine affects the heart less than the non DHP blockers..] Can someone please explain this?

Thanks

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[Transformers]

That is correct...class 4 blockersare affecting the phase 0 of the SAand AV node action potential...the dhp blockers do just that except block the channel in smooth muscles (see p 385 of first aid and think thats for Vessel smooth muscle)

 

[loveoforganic2]

I think the issue is that those phase 0 calcium channels are DHP-type. Or at least that's what I remember reading. I just shrugged it off though - heart stuff is pretty dumbed down for us, so there's probably some nuance that leads to the discrepancy in what we're told