Biomedical Engineering Reference
In-Depth Information
In general, all anion channels can be blocked by many unrelated classes of
compounds, bearing a negative charge at physiological pH. Even many small
anions, for example, HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic
acid) and MOPS (3-(N-morpholino)propanesulfonic acid) buffers, have been
found to block Cl
channels [
178
,
179
]. Transition metal cations, such as Zn
2+
,
Cd
2+
,La
3+
,Gd
3+
can also block anion channels; for example, Zn
2+
has been found
to block ClC-1 [
180
,
181
] and the GABA receptor [
182
,
183
], and Cd
2+
has been
often used to block ClC-2 channel [
184
-
186
].
4.4 Agents Acting on Other Cl
Channels
As discussed in the preceding section, some members of ClC channels could be
blocked by Zn
2+
and Cd
2+
ions. The inhibitors for the other chloride channels are
not so well studied. However, the Ca
2+
-activated chloride channels in mammalian
cells were found to be inhibited by niflumic and flufenamic acids (14,15)[
187
]as
well as by 5-nitro-2-(3-phenylpropylamino)benzoic acid (16, NPPB). In addition,
the disulfonic stilbene DIDS has also been found to potentially block the CaCC in
mammalian cells. For CLIC channels, indanylooxyacetic acid (17, IAA-94)
was found to be a potential blocker. This could block CLIC-1-induced currents
[
188
]. In addition, disulfonic stilbene DNDS (4,4
0
-dinitrodisulfonic stilbene and
TS-TM-calix(4)arene were also found to block p64-induced currents [
108
].
F
F
N
F
O
HN
OH
14, Niflumic acid
HO
O
F
F
H
N
F
15, Flufenamic acid
O
N
+
O
-
N
H
O
OH
16, 5-Nitro-2-(3-phenylpropylamino)benzoic acid
