voltage clamp 2012 - hebrew university of...
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AVout
+
-X
X1
Vcommand voltage follower
Rc
RI-elec
RV-elecin
diff ampIm
cm R
VI =
( )
( )
AwhenVVA
RRI
A
AVV
AVAVRRI
VVVARRI
VVRRI
VVAV
comm
Icmcomm
mcomIcm
mmcomIcm
moutIcm
mcomout
>>≈
+
+−
+=
−−=+
−−=+
−=+
−=
11
)(
1
)1()(
)(
)(
Vholding
clamping amplifier
pulse generator
current measurement
2
Vm
outRseries
A
CR mIc =τ
Clamping time-constant
בידוד זרמים יוניים) 1מניעת שינוי מתח ממברנה) 2קיבוע מתח דינאמי) 3
CmRm Vm
Discontinues single electrode voltage-clamp
5
Continues single electrode voltage clampR (electrode) <<< R (cell)
k = 24 mV z=1; 24mV e-fold change in P open example: gNa e-fold per 4mV zg = 24/4=6 e
)exp(kT
eEzw
C
O g−−=
13
“1-n” nβn
αn
τn = 1/(αn+βn)
n∞= αn /(αn+βn)
n(t) = n(∞) ( - n(∞) - n(0)) exp (-t/ τn )
4ngg KK =hmgg NaNa3=
14
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