Biomedical Engineering Reference
In-Depth Information
OH
O
N
H
N
F
20, Triflocine
O
NH
NH
S
N
O
O
NH
21, Torasemide
4.5.2 Apolar Cells
The red blood cells also act as Cl
transporters, where the Cl
flux occurs via the
band 3 protein, a form of bicarbonate/chloride exchange system [
192
]. This protein
is assumed to perform electroneutral anion exchange and to also permit the
channeling of Cl
. Its activity may thus be blocked by the compounds related to
stilbene, furosemide, and arylbenzoate classes.
4.6 Mechanism of Action of Anionic Channel Blockers
As discussed in a review by Greger [
166
], all Cl
channel blockers are essentially
converted into anionic form at physiological pH, in which the anionic group is
usually a carboxylate. All compounds also possess an amino bridge and an apolar
residue. The amino bridge is supposed to be necessary; it cannot be replaced by any
other group, such as oxygen, phosphorus, or carbon. The amino bridge may
probably be essential because of its ability to form a hydrogen bond acting as
a hydrogen-bond donor. An apolar group may be essential to have any hydrophobic
interaction with the receptor. In some group of compounds, the distances between
the amino and apolar groups and between amino and carboxylate groups are very
critical, for example, in the group of NPPB (16) derivatives, the optimal spacer
between the phenyl ring and the amino group was a propyl group. Replacing this
