4-acetamido-4--isothiocyanatostilbene-2-2--disulfonic-acid and hydroxide-ion

The SLC4A11 gene mutations cause a variety of genetic corneal diseases, including congenital hereditary endothelial dystrophy 2 (CHED2), Harboyan syndrome, some cases of Fuchs' endothelial dystrophy (FECD), and possibly familial keratoconus. Three NH2-terminal variants of the human SLC4A11 gene, named SLC4A11-A, -B, and -C are known. The SLC4A11-B variant has been the focus of previous studies. Both the expression of the SLC4A11-C variant in the cornea and its functional properties have not been characterized, and therefore its potential pathophysiological role in corneal diseases remains to be explored. In the present study, we demonstrate that SLC4A11-C is the predominant SLC4A11 variant expressed in human corneal endothelial mRNA and that the transporter functions as an electrogenic H(+)(OH(-)) permeation pathway. Disulfonic stilbenes, including 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS), 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonate (H2DIDS), and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonate (SITS), which are known to bind covalently, increased SLC4A11-C-mediated H(+)(OH(-)) flux by 150-200% without having a significant effect in mock-transfected cells. Noncovalently interacting 4,4'-diaminostilbene-2,2'-disulfonate (DADS) was without effect. We tested the efficacy of DIDS on the functionally impaired R109H mutant (SLC4A11-C numbering) that causes CHED2. DIDS (1 mM) increased H(+)(OH(-)) flux through the mutant transporter by ∼40-90%. These studies provide a basis for future testing of more specific chemically modified dilsulfonic stilbenes as potential therapeutic agents to improve the functional impairment of specific SLC4A11 mutant transporters.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Anion Transport Proteins; Antiporters; Biological Transport; Cell Line; Cornea; Endothelial Cells; HEK293 Cells; Humans; Hydroxides; Mutation; Permeability; RNA, Messenger; Signal Transduction

Organic ultraviolet (UV) rays absorbents have been used as sunscreen materials, but they may pose a safety problem when used at high concentration. In order to prevent direct contact of organic UV rays absorbent to the human skin, a typical organic UV-absorbent, 4,4(')-diaminostilbene-2,2(')-disulfonic acid (DASDSA), was intercalated into Zn(2)Al layered double hydroxide (Zn(2)Al-LDH) by coprecipitation reaction. However, deintercalation of DASDSA from Zn(2)Al-LDH, by the anion exchange reaction with carbonate ion, was observed. Therefore, Zn(2)Al-LDH/DASDSA was directly coated with silica by means of polymerization technique based on the Stöber method. Silica coating effectively depressed the deintercalation of DASDSA from Zn(2)Al-LDH. The amorphous silica was confirmed by XRD, SEM, TEM and FT-IR. The deintercalation behaviors as well as UV-shielding properties were investigated for coated particles.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; Hydrolysis; Hydroxides; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocomposites; Photochemistry; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Stilbenes; X-Ray Diffraction

Neutral NaCl absorption is the predominant Na+ absorptive process in rat distal colon. Whether this neutral NaCl absorptive process represents Na(+)-Cl- cotransport or dual ion exchanges of Na(+)-H+ and Cl(-)-OH- has been uncertain. Recent studies using rat colonic brush-border membrane vesicles (BBMVs) have described a Na(+)-H+ exchange mechanism and have proposed that net NaCl absorption occurs via a dual ion exchange process. To date, however, an anion exchanger on the colonic apical membrane has not been identified. To determine whether a Cl(-)-OH- exchange process is present, 36Cl uptake was evaluated across rat distal colonic BBMVs. A pH gradient (7.7 in/5.5 out) stimulated active Cl- uptake. Cl- uptake was not significantly affected by the presence of a valinomycin-induced K+ diffusion potential (inside positive), suggesting that a Cl- conductive pathway is not present in these membranes. The pH gradient-stimulated Cl- uptake was a saturable function of the Cl- concentration with a Km of 14.3 +/- 5.0 mM and a Vmax of 20.4 +/- 5.5 nmol.mg protein-1.30 s-1 and was almost completely inhibited by 1 mM concentrations of SITS and DIDS, inhibitors of anion exchange processes in other epithelia. Inward gradients of Na+, K+, or Na+ and K+ did not further stimulate initial Cl- uptake, suggesting that coupling of Na+ and Cl- movement does not occur by a cotransport mechanism. Thus a Cl(-)-OH- exchange process is present in rat distal colonic BBMVs.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Animals; Cell Membrane; Chlorides; Colon; Hydroxides; Intestinal Absorption; Kinetics; Male; Microvilli; Models, Biological; Muscle, Smooth; Rats; Rats, Inbred Strains; Sodium Chloride; Valinomycin

The effect of bicarbonate on the ability of cells to regulate the internal pH after acid and alkali loads was studied. In the presence of Na+, the normalization of the internal pH after acid loads occurred more rapidly in the presence than in the absence of bicarbonate. DIDS (4,4'-diisothiocyano-2,2'-stilbene-disulfonic acid) strongly inhibited the pH increase, whereas amiloride inhibited it to a lesser extent. The Na+-linked, bicarbonate-dependent pHi increase after an acid load was strongly reduced in cells depleted of Cl-. When cells were transferred to gluconate or mannitol balanced buffers containing bicarbonate, there was a rapid alkalinization of the cytosol, apparently due to influx of bicarbonate induced by chloride efflux. When the internal pH was below 7.0, the pH increase was much more rapid in the presence than in the absence of Na+, whereas at higher internal pH, there was no measurable effect of Na+. The ability of the cells to reduce the internal pH after an alkali load was increased in the presence of bicarbonate. The data indicate that both Na+-linked and Na+-independent bicarbonate/chloride exchange occur in Vero cells.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Amiloride; Ammonium Chloride; Animals; Anions; Bicarbonates; Biological Transport; Carrier Proteins; Cations, Monovalent; Chloride-Bicarbonate Antiporters; Chlorides; Hydrogen-Ion Concentration; Hydroxides; Sodium; Vero Cells