<s>
In	O
a	O
biological	O
membrane	O
,	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
is	O
the	O
membrane	O
potential	O
at	O
which	O
the	O
direction	O
of	O
ionic	O
current	O
reverses	O
.	O
</s>
<s>
At	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
,	O
there	O
is	O
no	O
net	O
flow	O
of	O
ions	O
from	O
one	O
side	O
of	O
the	O
membrane	O
to	O
the	O
other	O
.	O
</s>
<s>
For	O
channels	O
that	O
are	O
permeable	O
to	O
only	O
a	O
single	O
type	O
of	O
ions	O
,	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
is	O
identical	O
to	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
of	O
the	O
ion	O
.	O
</s>
<s>
The	O
equilibrium	B-Algorithm
potential	I-Algorithm
for	O
an	O
ion	O
is	O
the	O
membrane	O
potential	O
at	O
which	O
there	O
is	O
no	O
net	O
movement	O
of	O
the	O
ion	O
.	O
</s>
<s>
The	O
voltage	O
gradient	O
at	O
which	O
this	O
equilibrium	O
is	O
reached	O
is	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
for	O
the	O
ion	O
and	O
it	O
can	O
be	O
calculated	O
from	O
the	O
Nernst	O
equation	O
.	O
</s>
<s>
An	O
important	O
concept	O
related	O
to	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
is	O
the	O
driving	O
force	O
.	O
</s>
<s>
Driving	O
force	O
is	O
simply	O
defined	O
as	O
the	O
difference	O
between	O
the	O
actual	O
membrane	O
potential	O
and	O
an	O
ion	O
's	O
equilibrium	B-Algorithm
potential	I-Algorithm
where	O
refers	O
to	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
for	O
a	O
specific	O
ion	O
.	O
</s>
<s>
Note	O
that	O
the	O
ionic	O
current	O
will	O
be	O
zero	O
if	O
the	O
membrane	O
is	O
impermeable	O
to	O
that	O
ion	O
in	O
question	O
or	O
if	O
the	O
membrane	O
voltage	O
is	O
exactly	O
equal	O
to	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
of	O
that	O
ion	O
.	O
</s>
<s>
When	O
Vm	O
is	O
at	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
(	O
is	O
equal	O
to	O
0	O
)	O
,	O
the	O
identity	O
of	O
the	O
ions	O
that	O
flow	O
during	O
an	O
EPC	O
can	O
be	O
deduced	O
by	O
comparing	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
of	O
the	O
EPC	O
to	O
the	O
equilibrium	B-Algorithm
potential	I-Algorithm
for	O
various	O
ions	O
.	O
</s>
<s>
For	O
instance	O
several	O
excitatory	O
ionotropic	O
ligand-gated	O
neurotransmitter	O
receptors	O
including	O
glutamate	O
receptors	O
(	O
AMPA	O
,	O
NMDA	O
,	O
and	O
kainate	O
)	O
,	O
nicotinic	O
acetylcholine	O
(	O
nACh	O
)	O
,	O
and	O
serotonin	O
(	O
5-HT3	O
)	O
receptors	O
are	O
nonselective	O
cation	O
channels	O
that	O
pass	O
Na+	O
and	O
K+	O
in	O
nearly	O
equal	O
proportions	O
,	O
giving	O
the	O
reversal	B-Algorithm
potential	I-Algorithm
close	O
to	O
zero	O
.	O
</s>
<s>
The	O
inhibitory	O
ionotropic	O
ligand-gated	O
neurotransmitter	O
receptors	O
that	O
carry	O
Cl−	O
,	O
such	O
as	O
GABAA	O
and	O
glycine	O
receptors	O
,	O
have	O
reversal	B-Algorithm
potentials	I-Algorithm
close	O
to	O
the	O
resting	O
potential	O
(	O
approximately	O
–	O
70	O
mV	O
)	O
in	O
neurons	O
.	O
</s>
<s>
The	O
experiment	O
was	O
performed	O
by	O
lowering	O
the	O
external	O
Na+	O
concentration	O
,	O
which	O
lowers	O
(	O
makes	O
more	O
negative	O
)	O
the	O
Na+	O
equilibrium	B-Algorithm
potential	I-Algorithm
and	O
produces	O
a	O
negative	O
shift	O
in	O
reversal	B-Algorithm
potential	I-Algorithm
.	O
</s>
<s>
Conversely	O
,	O
increasing	O
the	O
external	O
K+	O
concentration	O
raises	O
(	O
makes	O
more	O
positive	O
)	O
the	O
K+	O
equilibrium	B-Algorithm
potential	I-Algorithm
and	O
produces	O
a	O
positive	O
shift	O
in	O
reversal	B-Algorithm
potential	I-Algorithm
.	O
</s>
