BIO304H5 Lecture Notes - Lecture 10: Calcium Channel Blocker, Bk Channel, Voltage Clamp
Document Summary
Slide 29: bk channels have a different mechanism for sensing calcium and responding to calcium, they do(cid:374)"t (cid:374)eed (cid:272)al(cid:373)oduli(cid:374, at their c-terminus, they have evolved their bone calcium sensor structure (calcium bowl) Instead the sk channels have the normal 4 helices, each channel has a calmodulin that calcium interacts with and tugs on it to open the channel. If you zoom out and look at what happens when you turn off the stimulation, you see a long lasting after hyperpolarization. If these hippocampal neurons fire an ap, there is this prolonged after depolarization after the ap that maintains this depolarization state over a period of time. If (cid:455)ou redu(cid:272)e that e(cid:454)ter(cid:374)al (cid:272)al(cid:272)iu(cid:373), (cid:455)ou still get the sodiu(cid:373) (cid:272)urre(cid:374)t, (cid:271)ut (cid:455)ou do(cid:374)"t ha(cid:448)e this counter-balancing potassium-calcium channel effect so the depolarization from the sodium leak becomes stronger and now you can fire a second ap.
