Drug interactions Flashcards
(23 cards)
tetracaine
inhibited by na+ current better at higher ph
benzocaine
inhibited na+ better at equal ph values
RAC-421 and QX-314
quaternary anaesthetics used by Hille determine whether the uncharged or charged form of the drug was acting
Lidocaine
antagonist used to inactivate the channels
Tetrodotoxin
- highly selective reversible blockers of VG na+ sodium channels.
- does not affect voltage dependence or inactivation
- binds to COOH residues in the pore and residues correspond to Glu387 in S6
Batrachotoxin
- acts on intracellular portions of channel, prevents inactivation and moves activation potential to more negative values
- channel opens far more readily than without the toxin
Scorpion toxins
- various toxin
- acts on outside of VG Na+ channels to inhibit inactivation
- acts alongside batrachotoxin
classes of drugs acting calcium channels
dihydropyridines, phenylalkylamines, benzothiazepines
Dihydropyridines
nifedipine, acts on S6 domain IV and part of the S5-6 loop in domain III
Phenylalkylamines
verapamil, acts on S6 part of the S5-6 loop in domain IV
Benzothiazepines
diltazem - blocks from the outside, modulate dihydropyridine binding
Spermine
intracellular polyamine accounts for occlusion producing rectification
Ina
produced by VGna, responsible for depolarising phase of action potential
Ica-L
produced by L-type Ca2+, main current during the plateau
Ica-T
produced by T-type ca2+ channels and present in nodal and conductive
Ina-ca
- electrogenic activity of the na+/ca2+ exchanger
- this serves to remove ca2+ from the cell which has entered through ca2+ channels during the plateau
- activity is affected indirectly by cardiac glycosides, used to treat heart failure
Ito1 and Ito2
produced by vg K+ channels. they reactivate rapidly in phase 0, inactivate rapidly.
this activates and inactivates behaviour gives the current its name of transient outward
- responsible for the small notch of the action potential that constitutes phase 1
iks
- delayed rectifier current properties.
- that means it activates with a delay after depolarisation with little or no inactivation
- contribute outward current during plateau and thus control the timing of depolarisation
- result of KCNE1 and KvLQT2
ikr
- delayed rectifier
- mutations can cause long QT syndrome
ikur
- third delayed rectifier
Ikp/icl
ikp is a plateau current, shows no rectification or voltage sensitivity
icl is the chloride current, channel responsible for icl is probably CFTR
Ik1
- inward rectifier stabiliser the resting potential and preventing k+ loss.
- ikach and ikatp and produce the same sort of current
if
pacemaker current
