calcium channel blocker文章.ppt

Calcium Channel Bs) - Calcium Antagonists
The role of Ca2+
Action potential of excitable cells
Contraction of muscle cells
Neurotransmitter release
As a second messenger
As a cofactor of enzymes
Blood-clotting 
Bone formation.
Regulation of cell Ca2+ concentration
Intracellular ca2+ conce. 100 nM.
Extracellular ca2+ conce. 1 mM.
Types of calcium channels
voltage-dependent calcium channels
High-voltage gated: L-type, N-type and P/Q-type
Intermediate voltage gated: R-type
Low-voltage gated: T-type
ligand-gated calcium channels (receptor-operated calcium channels )
R
Gq
PLCb
IP3
Receptor-dependent Ca2+ channel
Voltage-dependent Ca2+ channel
Resting
Activated
Inactivated
Main Subtypes of Voltage-Dependent Calcium Channels
L-type calcium channel: Most often found in smooth & skeletal muscles, cardiac cells, responsible for prolonged action potential, resulting in the contraction of cardiac and smooth, sinuatrial node(窦房结)pacing, atrioventricular conduction(房室间传导).
Cardiac cells rely on L-type Ca2+ channels for contraction
and for the upstroke of the AP in slow response cells
Contractile Cells
(atria, ventricle)
L-Type
Ca2+
Ca2+
Ca2+
Slow Response Cells
(SA node, AV node)
L-Type
Ca2+
Ca2+
Vascular smooth muscle relies on Ca2+ influx
through L-type Ca2+ channels for contraction
(graded, Ca2+ dependent
contraction)
L-Type
Ca2+
Main Subtypes of Voltage-Dependent Calcium Channels
T-type calcium channel: Most often found in neurons, and cells that have pacemaker activity
N-type and P/Q-type calcium channel: Most often found in the brain and peripheral nervous system, responsible for the release of neurotransmitters.
N-type and P/Q-type Ca2+ channels mediate
neurotransmitter release in neurons
postsynaptic cell
Ca2+
Ca2+
Ca2+
Ca2+
Ca2+