Voltage clamp 2012 - Hebrew University of...
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Current clamp Voltage clamp voltage command current command 1 dt dv C I I CV Q i m + = = I C R C I R I m
Transcript of Voltage clamp 2012 - Hebrew University of...
Current clamp Voltage clamp
voltage command
current command
1
dt
dvCII
CVQ
im +=
=
IC
R
C
IR
Im
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
dvCII
CVQ
+=
=
Current clamp Voltage clamp
3
dtCII im +=
A
CR mIc =τ
4
Discontinues single electrode voltage-clamp
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Continues single electrode voltage clampR (electrode) <<< R (cell)
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( )smss EVgI −=
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8
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10
K
KK
Na
NaNa
EE
Ig
EE
Ig
−=
−=
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12
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−−=
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“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=
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Dynamic clamp
