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PubMed1987

Renal tubular secretion of the alkanesulfonate 2,3-dimercapto-1-propanesulfonate.

The in vivo tubular secretion and metabolism of 2,3-dimercapto-1-propanesulfonate (DMPS) was examined in the chicken by use of the Sperber technique. Infusion of DMPS into the renal portal circulation of the chicken at rates equal to or less than 7.5 mumol X min-1 X kg body wt-1, resulted in a tubular excretion ratio of 0.5 for DMPS with 90% of the infused DMPS excreted in the urine unchanged. Renal tubular secretion accounted for approximately 90% of the total DMPS excreted into the urine during the infusion of DMPS at a rate of 0.75 mumol X min-1 X kg-1. The secretion of DMPS was saturable and was inhibited by p-aminohippurate (PAH), probenecid, and heptanesulfonate. Taurine (2-aminoethanesulfonate), isethionate (2-hydroxyethanesulfonate), and 2-mercaptoethanesulfonate had no effect on the secretion of DMPS or PAH. Renal tubular secretion may explain several pharmacological characteristics previously reported for DMPS, including the selective removal of heavy metals from the kidney.

Alkanesulfonates↗
PubMed1986

Electrolyte permeabilities of pancreatic zymogen granules: implications for pancreatic secretion.

Zymogen granules from rat pancreas were prepared on a 40% Percoll gradient at free calcium levels less than 0.2 microM. We have previously shown [Am. J. Physiol. 246 (Gastrointest. Liver Physiol. 9)] that zymogen granules prepared by this method are stable in vitro for more than 1 h in "physiological buffers." The electrolyte permeabilities of the zymogen granule membrane were investigated to determine the basis for this stability. Ionic permeabilities were estimated from rates of osmotic lysis and measured as decrease in optical density (OD) of granule suspensions. OD correlated linearly with lysis, as indicated by release of amylase, except for the highest and lowest 10% of the OD of intact granules. Lysis of freshly isolated granules was slow in Na+ or K+ salt solutions (e.g., t1/2 approximately 3 h for Cl-) but was accelerated 5- to 50-fold when cation ionophores were present simultaneously. This behavior indicates that zymogen granules have low endogenous permeabilities to the cations Na+ and K+, but are highly permeable to a variety of anions. Both anion conductance and anion-exchange pathways were found. The relative selectivity of the anion conductance pathway was SCN- greater than Br- approximately NO-3 greater than SO2-(4) greater than acetate- approximately Cl- greater than isethionate-. The relative selectivity sequence for anion/-OH- exchange was acetate- greater than SCN- greater than Br- approximately NO-3 approximately Cl- much greater than isethionate- greater than SO2-(4). The anion transport blocker DIDS blocked the electrogenic pathway with a half-maximal effectiveness at approximately 2 microM. DIDS had little effect on the anion-exchange pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1988

Role of bicarbonate in biliary excretion of diisothiocyanostilbene disulfonate.

Hepatic transport of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) was studied in isolated perfused rat livers and in isolated rat hepatocytes to determine if DIDS-induced decrease in biliary HCO3- excretion is due to a DIDS-HCO3- exchange and/or due to inhibition of Cl(-)-HCO3- exchange. In isolated perfused rat livers, DIDS reversibly decreased biliary HCO3- concentration and excretion. The changes in biliary HCO3- concentration were inversely related to biliary DIDS concentration. DIDS was concentrated in bile, indicating active hepatic transport. Replacement of perfusate HCO3- with equimolar dimethyloxazolidinedione (DMO) or tricine decreased biliary excretion, but not hepatic uptake, of DIDS. Biliary excretion of DIDS was also associated with a decrease in bile pH, and this decrease in pH was greater in the presence of HCO3-. HCO3-, but not DMO or tricine, stimulated DIDS efflux from preloaded hepatocytes. DIDS efflux was also temperature dependent and increased with increasing extracellular pH. Collectively, these results are consistent with the presence of a DIDS-HCO3- (OH-) exchange mechanism at the canalicular membrane. HCO3(-)-dependent Cl- uptake in hepatocytes was competitively inhibited by DIDS (Ki = 0.24 mM), confirming the presence of DIDS-inhibitable Cl(-)-HCO3- exchange. However, the ability of DIDS to decrease biliary HCO3- excretion persisted when perfusate Cl- was replaced by isethionate. Moreover, biliary HCO3- concentration returned to base line despite the presence of 2-6 mM DIDS in bile. Thus it seems unlikely that the inhibition of Cl(-)-HCO3- exchange by DIDS is a major mechanism of inhibition of HCO3- excretion. We, therefore, conclude that a DIDS-HCO3- (OH-) exchange at the canalicular membrane is the most likely explanation for the observed decrease in biliary HCO3- excretion.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1996

Sulfonates: novel electron acceptors in anaerobic respiration.

The enrichment and isolation in pure culture of a bacterium, identified as a strain of Desulfovibrio, able to release and reduce the sulfur of isethionate (2-hydroxyethanesulfonate) and other sulfonates to support anaerobic respiratory growth, is described. The sulfonate moiety was the source of sulfur that served as the terminal electron acceptor, while the carbon skeleton of isethionate functioned as an accessory electron donor for the reduction of sulfite. Cysteate (alanine-3-sulfonate) and sulfoacetaldehyde (acetaldehyde-2-sulfonate) could also be used for anaerobic respiration, but many other sulfonates could not. A survey of known sulfate-reducing bacteria revealed that some, but not all, strains tested could utilize the sulfur of some sulfonates as terminal electron acceptor. Isethionate-grown cells of Desulfovibrio strain IC1 reduced sulfonate-sulfur in preference to that of sulfate; however, sulfate-grown cells reduced sulfate-sulfur in preference to that of sulfonate.

Anaerobiosis↗
PubMed1992

Studies of transepithelial Cl- transport in cultured cauda epididymal cells of rats by the short-circuit current method.

1. Monolayer cultures of cauda epididymides from male Sprague-Dawley rats (210-230 g) were studied by the short-circuit current (ISC) technique to characterize the properties of the transepithelial chloride transport. In HCO(3-)-free, HEPES-buffered solution, adrenaline (0.23 microM) added to the basolateral side led to an increase in ISC and transepithelial conductance (gt). 2. Decreasing apical chloride concentration ([Cl-]a) progressively from 126.7 to 0 mM by substituting chloride with gluconate increased the ISC response to adrenaline (delta ISC) in a linear fashion with a slope of -1.6 x 10(-3) mu equiv h-1 cm-2 per millimolar change in [Cl-]a. Pretreating the tissue with a chloride channel blocker diphenylamine-2-carboxylate (DPC) on the apical side significantly reduced the slope to -4.9 x 10(-4) mu equiv h-1 cm-2 per millimolar change in [Cl-]a. 3. By substituting apical chloride with various anions and measuring the change in ISC upon adrenaline stimulation, the selectivity sequence of the apical anion conductance was found to be NO3- approximately Br- > Cl- > I- > gluconate > isethionate. 4. When the monolayers were bathed with Krebs-Henseleit solution containing 25 mM HCO3- and 5% CO2, the delta ISC at each [Cl-]a as well as the dependence of delta ISC on [Cl-]a (slope = -3.3 x 10(-3) mu equiv h-1 cm-2 per millimolar change in [Cl-]a) were significantly greater than the HCO(3-)-free counterpart. Addition of 0.1 mM acetazolamide or 0.5 mM SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) to the basolateral side significantly reduced the effects of HCO3- and CO2. 5. When the tissues were bathed on both sides with HCO(3-)-free, HEPES-buffered solution and were clamped at various transepithelial potential differences (PDt) from +30 mV (lumen positive) to -30 mV (lumen negative), the relationship between the clamping current response to adrenaline (delta ICL) and the PDt applied was linear. Zero clamping current response was found at -6 mV. Decreasing [Cl-]a to 0 mM reduced the dependence of delta ICL on PDt and delta ICL was positive at all PDt tested. The response of the transepithelial conductance to adrenaline (delta gt) did not depend on the PDt applied but was reduced with decreasing apical chloride concentration.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Absence of Cl- -OH- or Cl- -HCO3- exchange in the rabbit renal proximal tubule.

Coupled entry of Na+ and Cl- into the cell may mediate salt and water absorption by the renal proximal tubule. Other leaky epithelia have been shown to have parallel luminal Na+-H+ and Cl- -OH- exchangers that can serve in concert as a major pathway for NaCl absorption. Experiments were designed to test whether Cl- -OH- or Cl- -HCO3- exchange occurs in the isolated perfused rabbit proximal convoluted tubule and thereby whether neutral transcellular NaCl absorption could be a possible mode of active transport in this segment. The studies described here make use of a lumen-to-cell gradient for Cl- to drive OH- from cell to lumen, causing an increase in the rate of H+ disappearance from the luminal fluid. Superficial proximal convoluted tubules were perfused in vitro with acidic solutions (pH 6) that were generally free of organic solutes. The bathing solution contained organics, colloid, and less than 10% of perfusate H+ concentration. H+ disappearance was calculated from the difference in pH between perfused and collected fluid, flow rate, and buffer capacity of the perfusate. The removal of Na+ from perfusate and bath reduced H+ efflux to 68% of control, a smaller effect than that noted previously in the presence of organic solutes. When Na+-containing solutions were used, bilateral replacement of Cl- by NO3-, isethionate, or SO2-(4) failed to reduce H+ efflux, but rather resulted in a 11% increase in H+ flux.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1995

Characterization of two distinct Cl- conductances in fused human respiratory epithelial cells. II. Relation to cystic fibrosis gene product.

The present microelectrode experiments on fused respiratory epithelial cells of cystic fibrosis (CF) origin and non-CF origin aim at characterizing the molecular basis of the Cl- conductances regulated by cyclic adenosine monophosphate (cAMP) or respectively Ca2+, as described in the preceding publication. Cell membrane potential (Vm) and resistance (Rm) were recorded as well as their response to substitution of 90% of bath Cl- by isethionate (delta Vm,ISE), by I- (delta Vm,I), or by other halide anions. Fused CF cells had significantly (P < 0.05) higher control Vm values (-18.0 +/- 9.4 mV, +/- SD, n = 68) than fused non-CF cells (-12.5 +/- 6.6 mV, n = 69) and responded to the Ca2+ ionophore A23187 with an increase in the Vm response to Cl- substitution, but did not respond to forskolin. This indicates that CF cells express only the Ca(2+)-stimulated Cl- conductance. Injection of the antibody M3A7 against a fusion protein containing amino acids 1195 to 1480 of the CF gene product into young, forskolin-stimulated or old non-CF cells decreased delta Vm,ISE and delta Vm,I within 15 min to values observed in CF cells. This indicates inhibition of the cAMP-stimulated Cl- conductance and supports the molecular identity of this conductance with the CF gene product. However, the slow onset of inhibition does not allow secondary effects to be excluded and a slight fall in Rm remains unexplained. Stimulation of the Ca(2+)-regulated Cl- conductance was not impaired. Injection of M3A7 into CF cells or of a control antibody in non-CF cells had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1991

Mechanisms of ionophore-induced stimulation of renin secretion with special reference to a chemiosmotic hypothesis.

The effects of several ionophores on renin secretion were investigated in rabbit renal cortical slices. When slices were incubated in the absence of Ca++, the K+ ionophore valinomycin (10(-5) approximately 5 x 10(-4) M) or the monovalent cation ionophore nonactin (10(-4) M) stimulated renin secretion about 2-fold. The renin secretion stimulated by valinomycin was further increased by inclusion of the H+ ionophore, carbonylcyanide m-chlorophenylhydrazone. The electroneutral K+/H+ exchange ionophore nigericin (10(-5) approximately 5 x 10(-4) M) stimulated renin secretion in a dose-dependent manner, producing a maximal stimulation of about 17-fold. Another electroneutral exchange ionophore, monensin, also significantly stimulated secretion. The stimulation by both valinomycin and nigericin was apparent whether slices were incubated in Na(+)-rich or K(+)-rich media. The extent of stimulation by the two ionophores was dependent upon the presence of anion with acetate greater than Cl greater than isethionate greater than thiocyanate. Thiocyanate itself markedly inhibited renin secretion. Incubating of slices in an iso-osmotic ammonium acetate medium which is known to induce rapid swelling of secretory granules, stimulated renin secretion to the magnitude comparable to that of maximal stimulation by nigericin in a potassium acetate medium. The pattern of response to these ionophores indicates that changes in K+, H+ and anion gradients across the renin secretory granule may modulate renin secretory rate. It is proposed that conditions which allow accumulation of K+ and anion within acidic renin secretory granules lead to osmotic swelling of the granules and that granule swelling may promote exocytosis.

Animals↗
PubMed2001

Alkanesulfonate degradation by novel strains of Achromobacter xylosoxidans, Tsukamurella wratislaviensis and Rhodococcus sp., and evidence for an ethanesulfonate monooxygenase in A. xylosoxidans strain AE4.

Novel isolates of Achromobacter xylosoxidans, Tsukamurella wratislaviensis and a Rhodococcus sp. are described. These grew with short-chain alkanesulfonates as their sole source of carbon and energy. T. wratislaviensis strain SB2 grew well with C(3)-C(6) linear alkanesulfonates, isethionate and taurine, Rhodococcus sp. strain CB1 used C(3)-C(10) linear alkanesulfonates, taurine and cysteate, but neither strain grew with ethanesulfonate. In contrast, A. xylosoxidans strain AE4 grew well with ethanesulfonate, making it the first bacterium to be described which can grow with this compound. It also grew with unsubstituted C(3)-C(5) alkanesulfonates and isethionate. Hydrolysis was excluded as a mechanism for alkanesulfonate metabolism in these strains; and evidence is given for a diversity of uptake and desulfonatase systems. We provide evidence for an initial monooxygenase-dependent desulfonation in the metabolism of ethanesulfonate and propanesulfonate by A. xylosoxidans strain AE4.

Actinomycetales↗
PubMed2001

A maxi Cl- channel in cultured pavement cells from the gills of the freshwater rainbow trout Oncorhynchus mykiss.

Primary cultures of pavement cells from the gills of a freshwater fish, the rainbow trout Oncorhynchus mykiss, have been studied for the first time using the patch-clamp technique. Gigaohm seals were obtained in approximately 95% of cells studied, and channel activity was evident in a high proportion (>90%). A large-conductance Cl- channel was evident in 6 % of cell-attached and in 31% of inside-out patches. Single-channel conductance in inside-out patches was 372 pS, and current/voltage relationships were linear over the range -60 to +60 mV. The channel was activated by patch excision, and activation was often associated with polarization of the patch. The mean number of channels per patch was 1.9, and there were several subconductance states. The relationship between channel activity (NP(o)) and voltage was in the form of an inverted U, and channel activity was highest between 0 and +20 mV. Large-conductance Cl- channels showed a progressive time-dependent reduction in current in response to sustained polarization to voltages outside the range -20 mV to +20 mV. Permeability ratios (P) of Cl- to other anions were P(HCO3)/P(Cl)=0.81, P(SO4)/P(Cl)=0.31 and P(isethionate)/P(Cl)=0.53. The channel was blocked by Zn2+, SITS, DIDS and diphenylamine carboxylate. This is the first description of a large-conductance Cl- channel in gill cells from freshwater or marine species. Possible functions of the channel are discussed.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1986

Luminal alkalinization in the intestine of the goby.

The rate of luminal alkalinization in vitro by Gillichthys mirabilis posterior intestine as measured by a manual pH stat technique was 0.70 +/- 0.05 mu Equiv/cm2 h; acidification of the mucosal medium was never observed. The rate of HCO-3 secretion (JHCO3) was reduced by ouabain, serosally-applied DIDS, removal of serosal HCO3- and replacement of media Cl- with gluconate. HCO3- secretion was enhanced by replacement of Cl- with isethionate and unaffected by mucosal DIDS, furosemide or acetazolamide. JHCO3 was reduced at mucosal pH above or below 7.5. These results support active HCO3- secretion via a Cl-/HCO3- exchange mechanism on the basolateral membrane and a conductive exit pathway for HCO-3, H+ or OH- on the apical membrane.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1988

Relative contributions of passive equilibrium and active transport to the distribution of chloride in mammalian cortical neurons.

1. Active and passive factors affecting the chloride gradient of cortical neurons were assessed using intracellular recordings from neurons in slices of cingulate cortex maintained in vitro. The chloride equilibrium potential (ECl-) was estimated indirectly from the reversal potentials of responses to perisomatic gamma-aminobutyric acid (GABA) application and the Cl(-)-dependent inhibitory postsynaptic potential (IPSP). Under control conditions the mean resting potential (Vm; -69.7 mV) was not significantly different than the mean IPSP reversal potential (EIPSP; -70.1 mV). 2. Increasing the external potassium concentration ([K+]o) from 1 to 10 mM shifted the mean EIPSP from -80.4 to -61.8 mV. The mean EIPSP was approximately equal to the mean Vm at all [K+]oS. The conditions of Donnan equilibrium are not met in [K+]o less than 10 mM. 3. Polarization of Vm up to 20 mV away from EIPSP for 4 min with maintained current injection had no significant effect on EIPSP. 4. The GABA reversal potential was maintained 37-52 mV less negative than Vm after equilibration in saline in which the external chloride concentration had been reduced from 133 to 5 mM by substitution with isethionate. Vm and input resistance were not significantly different from control values in cells recorded under these conditions. 5. We conclude that Cl- is not passively distributed in cortical neurons, perhaps due to a low resting Cl- permeability. 6. Impalement with electrodes containing 2 M KCl resulted in a rapid 10 mV depolarizing shift in EIPSP that then remained relatively constant. Intracellular iontophoresis of Cl- resulted in a further depolarizing shift of EIPSP of 5-10 mV that returned to control in less than 1 min. The time course of recovery of IPSP amplitude could be fit with a single exponential having a mean time constant of 6.9 +/- 1.5 s and was independent of the amount of Cl- injected or stimulation frequency. 7. Reductions in temperature from 37 to 32 degrees C significantly increased the mean time constant of IPSP recovery from Cl- injection to 11.1 +/- 3.3 s, corresponding to Q10 = 2.6.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

A voltage-gated chloride conductance in rat cultured astrocytes.

Large voltage-dependent outward currents are recorded with the whole-cell patch-clamp technique from rat cultured astrocytes under conditions where an outward movement of potassium ions is excluded (either by blockage of the potassium channels pharmacologically or by replacement of the internal potassium by the impermeant large organic cation N-methyl-(+)-glucamine). The current, which is activated at potentials more positive than -40 to -50 mV, is normally carried by an inward movement of chloride ions. Its reversal potential is the same as the chloride equilibrium potential. With depolarization to +60 mV (for 225 ms) little or no inactivation of the current occurs: with depolarizations to +90 to +110 mV a time-dependent decay is seen. The current, which is often not marked immediately after formation of the whole-cell clamp, generally increases over a period of a few minutes to a maximum (after which it usually declines), as if some as yet unknown intracellular factor keeping the channels closed were being washed away from the membrane. The time course of this phenomenon is not affected by changing of the internal free calcium concentration (from 10(-8)M to 10(-6)M) or by an intracellular mixture of cyclic AMP (1 mM), ATP (4 mM) and Mg+ (2 mM). The conductance is slightly increased when the chloride of the bathing medium is replaced by bromide; is much reduced on replacement by methylsulphate, sulphate, isethionate, or acetate; and is virtually abolished on replacement by the large anion gluconate. The outward current is inhibited by the disulphonate stilbenes DIDS and SITS; this blocking action was initially partly reversible, although never completely so. It is suggested that the chloride conductance plays a role in the spatial buffering of potassium by astrocytes.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1991

Interactions of magnesium and chloride ions on tone and contractility of vascular muscle.

Replacement of extracellular chloride ions ([Cl-]o) by other anions, on contractility and the effects of extracellular magnesium ions ([Mg2+]o) on spontaneous mechanical activity, as well as on agonist-induced responses of rat aorta and portal vein, were studied. Replacement of [Cl-]o with acetate (Ac-) or isethionate (Ise-) ions resulted in an increase and decrease, respectively, of the spontaneous mechanical activity frequency in portal vein; the amplitudes of the spontaneous mechanical activity were attenuated by Ac- and Ise- substitution. Withdrawal of [Mg2+]o in Cl(-)-containing media resulted in elevation of tension development in rat aortas, whereas a similar maneuver in media with Ac- or Ise-, substituted for [Cl-]o, resulted in abrogation of this tension development. Use of disulfonic stilbene anion-channel blockers, DIDS (4,4'-diisothiocyano-2,2'-stilbene disulfonate, 400-600 microM) and SITS (4,4'-acetamido-4'-isothiocyano-2,2'-stilbene disulfonic acid, 400-600 microM), failed to influence either spontaneous mechanical activity or basal tone of rat portal portal vein or aortas. Incubation of DIDS or SITS in Mg(2+)-free media also failed to influence mechanical responses to withdrawal of [Mg2+]o. Use of the Cl- cation transport inhibitor bumetanide (30-80 microM) also failed to alter spontaneous mechanical activity or basal tone in either the presence or absence of [Mg2+]o. Ac- and Ise- substitution attenuated norepinephrine- and K(+)-induced contractile responses in portal vein and aorta, Caffeine-induced contractions of aortas were potentiated by withdrawal of [Mg2+]o in Cl(-)-containing media but inhibited in Ac(-)- or Ise(-)-substituted solutions. In the presence of [Mg2+]o, substitution of foreign anions resulted in alterations in the agonist contractile dose-response curves; EC50s were increased whereas maximum tensions were depressed. Withdrawal of [Mg2+]o amplified these effects. Substitution of Ac- or Ise- for [Cl-]o in the presence or absence of [Mg2+]o depressed contractions induced by Ca acetate in aortas and portal vein. These results suggest that: (1) Cl- plays an important role in regulating spontaneous mechanical activity, basal tone, and contractility in rat aorta and portal vein; and (2) Cl- probably physiologically mediates some of the effects and actions of [Mg2+]o on intracellular release of and influx of Ca2+ in these smooth muscles.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1999

Sulfonates as terminal electron acceptors for growth of sulfite-reducing bacteria (Desulfitobacterium spp.) and sulfate-reducing bacteria: effects of inhibitors of sulfidogenesis.

This study demonstrates the ability of Desulfitobacterium spp. to utilize aliphatic sulfonates as terminal electron acceptors (TEA) for growth. Isethionate (2-hydroxyethanesulfonate) reduction by Desulfitobacterium hafniense resulted in acetate as well as sulfide accumulation in accordance with the expectation that the carbon portion of isethionate was oxidized to acetate and the sulfur was reduced to sulfide. The presence of a polypeptide, approximately 97 kDa, was evident in isethionate-grown cells of Desulfitobacterium hafniense, Desulfitobacterium sp. strain PCE 1, and the two sulfate-reducing bacteria (SRB)-Desulfovibrio desulfuricans IC1 (T. J. Lie, J. R. Leadbetter, and E. R. Leadbetter, Geomicrobiol. J. 15:135-149, 1998) and Desulfomicrobium norvegicum; this polypeptide was not detected when these bacteria were grown on TEA other than isethionate, suggesting involvement in its metabolism. The sulfate analogs molybdate and tungstate, effective in inhibiting sulfate reduction by SRB, were examined for their effects on sulfonate reduction. Molybdate effectively inhibited sulfonate reduction by strain IC1 and selectively inhibited isethionate (but not cysteate) reduction by Desulfitobacterium dehalogenans and Desulfitobacterium sp. strain PCE 1. Desulfitobacterium hafniense, however, grew with both isethionate and cysteate in the presence of molybdate. In contrast, tungstate only partially inhibited sulfonate reduction by both SRB and Desulfitobacterium spp. Similarly, another inhibitor of sulfate reduction, 1,8-dihydroxyanthraquinone, effectively inhibited sulfate reduction by SRB but only partially inhibited sulfonate reduction by both SRB and Desulfitobacterium hafniense.

Adenosine Triphosphate↗
PubMed2004

Inhibition of wortmannin activities by amino compounds.

Wortmannin caused normal and strong inhibition on catecholamine secretion from bovine adrenal chromaffin cells and in vitro phosphoinositide 3-kinase activity in NaCl-, Na isethionate-, choline Cl-, Na acetate-, and N-acetyl glycine-based media. However, brief preincubation of wortmannin with the media containing amino compounds such as glutamate, aspartate, lysine, and glycine resulted in the prevention of the inhibitory effects of wortmannin on the above responses as two indexes of wortmannin activities. On the other hand, the amino compounds also caused several rapid changes in wortmannin medium; the changes in absorption spectrum of the medium; and the changes in the retention time of the peak on the HPLC chromatogram using a reverse-phase C-18 column and in the pattern of absorption spectrum of the peak. These changes were not observed in the cases of NaCl, Na isethionate, choline Cl, Na acetate or N-acetyl glycine. Another amino compound Tris, which was commonly used as a pH buffer, was unique in time course and induced the slow but parallel changes and reached maximal up to about 24h. These results taken together indicate that the amino compounds markedly inhibit the activities of wortmannin presumably through the binding of wortmannin to amino group.

Amines↗
PubMed1980

Cl- dependence of HCO3- transport in frog gastric mucosa.

Frog (Rana temporaria) fundic mucosae in vitro were pretreated with the histamine H2 receptor antagonist Metiamide (10(-3)M, nutrient side) until net H+ secretion had ceased and a steady rate of HCO3- transport (luminal alkalinization) was titrated. Removal of Cl- with SO4(2) or isethionate replacement from solutions bathing both sides of the mucosa abolished luminal alkalinization. Readdition of Cl- to the luminal side only reestablished full rates of HCO3- transport. Nutrient (serosal) side Cl- had no effect in this aspect. The results support the previous suggestion that the gastric HCO3- transport process is located at the luminal membrane of the surface epithelial cells and indicate that it occurs by (electroneutral) HCO3-/Cl- exchange.

Animals↗
PubMed1999

Antibiotic and biocide resistance in methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococcus.

Concern has been growing regarding the potential of antibiotic and disinfectant co-resistance in clinically important bacteria. In this study, the susceptibilities of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) to chlorhexidine (CHX), the quaternary ammonium compounds cetylpyridinium chloride (CPC) and benzalkonium chloride (BC), triclosan, dibromopropamidine isethionate (DBPI) and triclocarban were compared. MRSA exhibited low-level resistance to CHX and the QACs, with MICs of 1.5 to 3-fold (CHX), and 2 to 4-fold (QACs) higher than MSSA. However, the MIC values for MRSA ranged between 0.025 (the MIC of MSSA) and 1 microg/mL with triclosan, and between <5 (the MIC of MSSA) and 75 microg/mL with DPBI. Nevertheless, these strains remain relatively sensitive to most of these antimicrobial agents. The bactericidal efficacy of CHX, CPC and DBPI (with the exception of one strain) correlated with their MIC value. This was not observed using triclosan; MRSA and MSSA strains were equally susceptible to its killing effect, regardless of MIC. The permeabilizing agent, ethylenediamine tetraacetic acid (EDTA) was unable to potentiate the antibacterial activities of the biocides against any of the strains tested. Attempts to select for staphylococcal strains with increased resistance to triclosan, CPC or CHX, using disc diffusion, step-wise broth, or repeated exposure/recovery technique, were only partially successful, and resistance was found to be unstable. The susceptibilities of vancomycin-resistant enterococcus (VRE) and vancomycin-sensitive enterococcus (VSE) to the biocides were also compared and found to be similar both in terms of MIC testing and time-kill studies.

Anti-Bacterial Agents↗