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PubMed2001

Determination of butyl-, phenyl-, octyl- and tributylmonomethyltin compounds in a marine environment (Bay of Bengal, India) using gas chromatography-inductively coupled plasma mass spectrometry.

Organotin compounds (butyl-, phenyl-, octyl- and tributylmonomethyltin) and inorganic tin were quantified in sea-water and sediments from two harbours and several locations on the southeast coast of India using highly sensitive and selective gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS), adopting new extraction and analytical techniques with extremely low detection limits (water, 0.019-0.85 pg l(-1); sediment, 0.23-0.48 ng g(-1)). The concentrations of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) in sea-water from Tuticorin harbour varied from 0.64 to 4.97, 3.0 to 26.8 and 0.3 to 30.4 ng Sn l(-1), respectively. MBT, DBT and TBT in sediments from harbour areas ranged from 1.6 to 393, 1.3 to 394 and ND (not detected) to 1280 ng Sn g(-1) (dry weight), respectively. Natural methylation in both harbours was established by quantifying tributylmonomethyltin (TBMMT) residues (sea-water, ND-0.19 ng Sn l(-1); sediment, ND-765 ng Sn g(-1) dry weight). In sea-water, octyltins were also determined as monooctyltin (MOT) > dioctyltin (DOT) > trioctyltin (TOT). Butyltin contamination in commercial harbours is evident, but other coastal waters are not contaminated with organotin residues. The high concentration of inorganic tin in estuarine sediment indicates an elevated rate of debutylation in the estuarine environment. Both methylation and debutylation of TBT in Chennai harbour were greater than in Tuticorin harbour. A significant correlation (r2 = 0.75) between total butyltin and organic carbon contents in sediment was found. To our knowledge, this is the first report on the distribution of butyltins and methylated butyltin in sea-water and sediment and octyltins in sea-water in the Indian marine environment.

Carbon↗
PubMed2006

Effects of various pesticides on human 5alpha-reductase activity in prostate and LNCaP cells.

Certain pesticides are able to disturb the sex steroid hormone system and to act as antiandrogens. While the different underlying mechanisms remain unclear, inhibition of 5alpha-reductase, the enzyme which is indispensable for the synthesis of DHT and thus normal masculinization, appears to be one of the sensitive targets for endocrine disruption. We therefore tested several endocrine disrupters with antiandrogenic effects in vivo for their influence on 5alpha-reductase activity in two different test systems: (a) an enzyme assay with human Lymph Node Carcinoma of Prostate (LNCaP) cells and (b) an enzyme assay with human prostate tissue homogenate. The selected pesticides and industrial compounds were monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), triphenyltin (TPT), diuron, fenarimol, linuron, p,p'DDE, prochloraz and vinclozolin. The synthetic androgen methyltestosterone and the synthetic antiandrogen flutamide, as well as the 5alpha-reductase inhibitor finasteride served as control compounds. The effect of the organotin compounds DBT, TBT and TPT on enzyme activity was approximately the same in both test systems, with IC(50) values ranging between 2.7 and 11.2 microM, while in prostate tissue, methyltestosterone and prochloraz proved to be stronger inhibitors (IC(50) values of 1.9 and 12.4 microM) than in LNCaP cells (IC(50) values of 13.2 and 53.2 microM). The inhibitory impact of finasteride was approximately 130 times stronger in prostate tissue than in LNCaP cells. Fenarimol, flutamide, linuron and p,p'DDE inhibited 5alpha-reductase activity only at very high concentrations (IC(50)> or =24 microM) in prostate homogenates, and not at all in LNCaP cells. On average, the IC(20) values were 3.5 times lower than the IC(50) values. Diuron, MBT and vinclozolin exerted no effect in either of the test systems. The finding of pesticides acting as 5alpha-reductase inhibitors might be of clinical relevance. As a screening tool for putative ED, the tissue assay is the more practical and sensitive method. However, the cell assay can, to some extent, reflect particular cell processes since the living cell is able to compensate moderate toxicological effects of the ED on cell viability, and possibly also their impact on 5alpha-reductase activity.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2004

Organotin survey in the Adour-Garonne basin.

Organotin monitoring was performed in waters of 11 rivers of the southwest of France during a 9 months period, between February and October 2001. Surface sediments were studied during the summer. Eighteen sampling points were chosen as representative of specific industrial or agricultural activities. In most samples, organotins were detected and butyltins are the most frequently present, with concentrations ranging over 0.2-30 ng(Sn)/L. Phenyltins were detected especially in spring and at the end of summer, which corresponds to likely diffusion from agricultural sources. Some high butyl- and phenyltin concentrations up to 700 ng(Sn)/L occurred during the spring where pesticides for agricultural activities were largely used. Octyltins were present in water frequently as well, with lower concentrations, probably originating from continuous leaching of plastics. Sediments appeared contaminated by the same species, with higher monobutyltin concentrations of about 30-40 microg(Sn)/kg which shows the importance of biological degradations occurring in surface sediments. This non-pesticidal organotin compounds can also be introduced from leaching of organotin-stabilized PVC by water. Using the different organotin concentrations obtained and other physico-chemical parameters measured, such as temperature or water flow rate, a statistical study was performed by principal component analysis. The results obtained allow the main sources of organotin diffusion to be identified and the hydrological cycle of these compounds better understand.

Data Collection↗
PubMed2003

Inspection method for the identification of TBT-containing antifouling paints.

In order to ensure the effectiveness of the international convention which will prohibit the use of organotin compounds in antifouling paints applied to ships, it is essential to establish an inspection system to determine the presence of the prohibited compounds in the paint. In the present study, a method for the identification of organotin containing antifouling paints using a two-stage analysis process is investigated. Firstly, X-ray fluorescence analysis (XRF) is utilized, which could be used at the place of ship surveys or port state control. Using a portable XRF instrument customized for ship inspection, analysis is automatically executed and determines whether tin is present or not. If the presence of tin is confirmed by XRF, the sample is subsequently examined at an analytical laboratory using more rigorous analytical techniques, such as gas chromatograph mass spectrometry (GC-MS). A sampling device has been designed. It is a disc of approximately 10 mm diameter and has abrasive paper pasted to one of its flat surfaces. The device is pressed onto and then slid along a ship hull to lightly scrape off fragments of paint onto the abrasive paper. Preliminary field tests have revealed that sampling from a ship in dock yields successful collection of the paint for XRD analysis and that the resultant damage caused to the antifouling paint surface by the sampling technique was found to be negligible.

Environmental Monitoring↗
PubMed1997

[Selective extraction of organotin from biological sample by supercritical fluid extraction].

The preliminary separation and concentration of organotin compounds from the matrix of biological samples is necessary, due to the very low content of organotin and the fat included in samples will largely interfere the analysis of organotins. In this work, supercritical fluid extraction (SFE) for the preliminary separation and concentration of organotin has been studied. Pure CO2 was used as mobile phase. The extractives can be used to supercritical fluid chromatographic (SFC) analysis of organotins. The model sample was prepared by adding diphenyltin (DPT) to soya powder. The effects of the pressure and temperature on SFE were investigated. A small amount of fat was also extracted together with organotins. Extract was injected into SFC system, in which a Kapcell Pak ODS column was used for separation of organotin and fat. The effect of pressure on the extraction percentage of DPT and fat was investigated at 40 degrees C. At lower pressure (10-15 MPa), a maximum extraction efficiency (63%) was attained for DPT, while the fat is extracted only 28.3%. The increase in temperature is advantageous for the selective extraction of DPT. However, the extraction efficiency of DPT decreased as the extraction temperature was increased. When a lower pressure (10 MPa) and a higher temperature (50 degrees C) were used, the organotin (DPT) was extracted up to a maximum (59.9%) within 30 min, while fat was extracted only 4.9%.

Chromatography, Supercritical Fluid↗
PubMed1998

Immobilization of microalgae for biosorption and degradation of butyltin chlorides.

Since the discovery of their biocidal properties in the 1950s, organotin compounds have found a large spectrum of industrial applications such as wood and textile preservatives, fungicides and pesticides, and antifouling paint on ships and fishing equipment. The fate and environmental impact of butyltins have been the subjects of a large body of research in the last decades. Biosorption and degradation of butyltin compounds by immobilized microalgae chlorella were studied in this paper, aiming to find an alternative way to solve organotin pollution problem. Chlorella emersonii cells were entrapped in a calcium aginate matrix. The cell growth rates, respiratory rate and chlorophyll a content were studied and compared. Results showed that immobilized chlorella had increased respiratory and growth rates, and almost equal chlorophyll a content when compared with free cells. Cell leakage was slight during the 20-day experimental period Cell leakage from the matrix was unrelated to cell growth within the matrix. Immobilized chlorella was applied to deal with butytin contaminated aquatic solutions. Immobilized chlorella had increased degradation rates of tri-, di-, and mono-butyltin chlorides in aquatic solutions, and lower biological accumulation factors on cells, than free cells, which indicates a potential use for tackleing organotin polluted water body.

Absorption↗
PubMed1990

Na+/K(+)-ATPase in rat brain and erythrocytes as a possible target and marker, respectively, for neurotoxicity: studies with chlordecone, organotins and mercury compounds.

Due to the inaccessibility of human nerve tissue for direct biochemical evaluation, there appears to be a need to identify peripheral markers which will reflect toxicity to the central nervous system by relatively non-invasive means. The aim of this study was to investigate whether the enzyme Na+/K(+)-ATPase in erythrocytes could be used as a marker for effects on the same enzyme in brain tissue. The compounds chosen to test this hypothesis were the pesticide chlordecone, the organotin compounds triethyltin and tributyltin, mercuric chloride and methyl mercury. All compounds were found to inhibit in vitro Na+/K(+)-ATPase activity in rat brain (IC50s = 0.9-56 microM) and in rat erythrocytes (IC50s = 1.2-66 microM) with similar potencies. However, administration of these compounds in vivo at high doses produced no significant inhibition of either brain or erythrocyte Na+/K(+)-ATPase activity, despite observed symptoms of neurotoxicity. Dialysis experiments indicated that dissociation of the compounds by dilution during tissue preparation was not responsible for the lack of detectable in vivo inhibition. Measurements of metal concentrations in brain by atomic absorption spectrometry after in vivo administration of triethyltin, mercuric chloride and methyl mercury indicated that levels of these compounds were too low to inhibit significantly NA+/K(+)-ATPase activity. These results suggest that inhibition of Na+/K(+)-ATPase activity might not represent the mechanism responsible for the neurotoxicity of these compounds, and that erythrocyte Na+/K(+)-ATPase activity is not a useful marker for neurotoxicity following acute exposures.

Animals↗
PubMed2003

In vitro trypanocidal activity of dibutyltin dichloride and its fatty acid derivatives.

Searching for new compounds against pathogenic trypanosomes has been substantially accelerated by the development of in vitro screening assays. In an attempt to explore the chemotherapeutic potential of organotin compounds and to broaden the search for newer trypanocides, fatty acid derivatives of dibutyltin dichloride were synthesized and their in vitro trypanocidal profiles studied on Trypanosoma brucei brucei, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. A 24-h time course experiment was conducted with various concentrations of the compounds using a 24-well microtiter plate technique. The compounds tested were trypanocidal in a dose-dependent fashion: inhibiting survival and growth, resulting in irreversible morphological deformation and the eventual death of the parasites. The minimum inhibitory concentrations of the tested diorganotins are at low micromolar ranges: from 0.15-0.75 microM for T. b. brucei, T. b. gambiense and T. b. rhodesiense. These observations suggest that organotin has chemotherapeutic potential.

Animals↗
PubMed2001

Repeated administration of a mild acute toxic dose of di-n-butyltin dichloride at intervals of 3 weeks induces severe lesions in pancreas and liver of rats.

Di-n-butyltin dichloride (DBTC) induced thymus atrophy, bile duct lesions, pancreatitis, and liver lesions in rats. Depending on dose [6 and 8 mg/kg intravenous (i.v.) DBTC] and time (1-24 weeks), the lesions in pancreas developed to a pancreatic fibrosis and the lesions in liver to liver cirrhosis. A single i.v. administration of 4 mg/kg DBTC induces a mild interstitial pancreatitis after 2-4 days followed by a restitutio ad integrum after 21-28 days. In the present study, the lesions of biliopancreatic duct, pancreas, and liver of rats after repeated administration of 4 mg/kg DBTC i.v. at intervals of 3 weeks have been investigated. The histopathological changes of pancreas and liver were examined by light microscopy 1,4, and 7 days and 2,3,4,6,9, and 12 weeks after administration of DBTC. Furthermore, pathobiochemical parameters of pancreatitis (amylase and lipase activity in serum), liver lesions (alkaline phosphatase activity and bilirubin in serum), and of fibrosis (hyaluronic acid in serum) were studied. Repeated administration of rats with DBTC (4 mg/kg i.v.) at intervals of 3 weeks induced an acute interstitial pancreatitis and after 9-12 weeks, a pancreatic fibrosis and liver lesions (intrahepatic bile duct hyperplasia, inflammation in periportal tract, and necrosis). In serum, elevated levels of alkaline phosphatase, bilirubin, and hyaluronic acid were found. This study demonstrates that the organotin compound induces toxic effects on pancreas and liver of rats by repeated administration of lower doses at long intervals. The risk of exposure to organotin at long intervals should be considered.

Alkaline Phosphatase↗
PubMed1987

Acute pesticide poisoning in England and Wales.

Between 1979 and 1983 less than 1% of admissions from acute poisoning in the UK were due to pesticides and fewer than 4% of admissions in those under 5 years were from this cause. Organochlorine, organophosphorus and carbamate insecticides account for only 10% of the total in both children and adults. Suspected pesticide poisoning was the cause of fewer than 0.3% of home accidents in those under 10 years of age and less than 4% of suspected poisonings documented by the Home Accident Surveillance System. Rodenticides were thought to be involved in 62% of these cases. Of children who presented to hospital 42% were admitted and 93% of these were discharged home within 2 days. In the UK, the morbidity from acute pesticide poisoning in children is low and the mortality is nil and there is therefore no evidence to support the view that paediatric pesticide intoxication is a significant clinical problem. Though no fatalities were recorded in children, pesticides were responsible for 1.3% of all deaths due to poisoning in the UK between 1979 and 1983. In adults admitted to hospital, the mortality from pesticide poisoning is approximately 12% and three quarters of these deaths are due to the deliberate ingestion of paraquat. The general term pesticide refers to a group of products that are used as insecticides, acaricides, fungicides, herbicides, rodenticides, and plant growth agents. Chemically, the group includes bipyridilium compounds, carbamates, chloralose, chlorates, coumarins, dinitro compounds, dithiocarbamates, fluoroacetates, organochlorine organophosphorus and organotin compounds, pentachlorophenol, phenoxyacetates, phosphine (as magnesium and aluminium phosphides), pyrethrins, pyrethroids and triazines.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Inhibition of Ca2+ transport associated with cAMP-dependent protein phosphorylation in rat cardiac sarcoplasmic reticulum by triorganotins.

Organotin compounds have been shown to interfere with cardiovascular system. We have studied the in vitro and in vivo effects of tributyltin bromide (TBT), triethyltin bromide (TET) and trimethyltin chloride (TMT) on the cardiac SR Ca2+ pump, as well as on protein phosphorylation of SR proteins, in order to understand the relative potency of these tin compounds. All the three tin compounds inhibited cardiac SR 45Ca uptake and Ca(2+)-ATPase in vitro in a concentration-dependent manner. The order of potency for Ca(2+)-ATPase as determined by IC50, is TBT (2 microM) greater than TET (63 microM) greater than TMT (280 microM). For 45Ca uptake, it followed the same order i.e., TBT (0.35 microM) greater than TET (10 microM) greater than TMT (440 microM). In agreement with the in vitro results, both SR Ca(2+)-ATPase and 45Ca uptake were significantly inhibited in rats treated with these tin compounds, indicating that these tin compounds inhibit cardiac SR Ca2+ transport. cAMP significantly elevated (70-80%) the 32P-binding to SR proteins in vitro in the absence of any organotin. In the presence of organotins, cAMP-stimulated 32P-binding to proteins was significantly reduced, but the decrease was concentration dependent only at lower concentrations. The order of potency is TBT greater than TET greater than TMT. In agreement with in vitro studies, cAMP-dependent 32P bound to proteins was significantly reduced in rats treated with TBT, TET and TMT. SDS-polyacrylamide gel electrophoresis of the cardiac SR revealed at least 30 Coomassie blue stainable bands ranging from 9 to 120 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Toxicity evaluation of new antifouling compounds using suspension-cultured fish cells.

A simple, rapid toxicity test was developed using the suspension-cultured fish cell line CHSE-sp derived from chinook salmon Oncorhynchus tshawytscha embryos in order to assess the toxicity of new marine antifouling compounds. The compounds tested were copper pyrithione, Diuron, Irgarol 1051, KH101, Sea-Nine 211, and zinc pyrithione, all of which have been nominated in Japan as possible replacements for organotin compounds. The in vitro acute toxicity (24-h EC50) of the six compounds to these fish cells was evaluated using the dye Alamar Blue to determine cell viability, and then correlated with the results of in vivo chronic toxicities (28-day LC50) to juvenile rainbow trout Oncorhynchus mykiss. The suspension-cultured fish cells were found to be suitable for the screening of such chemicals before performing an in vivo test. The toxicities of the test compounds obtained from both tests, shown in decreasing order, were as follows: copper pyrithione > zinc pyrithione > KH101 > or = Sea-Nine 211 > Diuron > Irgarol 1051. The herbicides Diuron and Irgarol 1051 showed the least toxicity, while the pyrithiones had the greatest toxicity.

Animals↗
PubMed2004

Role of speciation in organotin toxicity to the yeast Candida maltosa.

Assessment of organometal pollution requires an understanding of the various processes that influence the bioavailability and toxicity of the contaminant. Organotins may exist as both cationic species and neutral hydroxides in aqueous solution, with the formation of chloride species in the presence of Cl-. Although these species have different chemical properties, there is very little information on the influence of speciation on organotin and microbial cell interactions. Tributyltin (TBT) and triphenyltin (TPT) interactions with the yeast Candida maltosa were investigated between pH 3.5 and 7.5 and in up to 0.5 M NaCl at pH 5.5. Toxicity increased with both pH and NaCl concentration and the mechanisms of interaction depended on the species present in solution. TBT and TPT interacted by different mechanisms, as evidenced by action on membrane fluidity. Furthermore, there was a strong correlation between toxicity and overall octanol-water distribution ratio (D(OW)) of organotin compounds. Triorganotin cations are less toxic than triorganotin hydroxides, which are in turn less toxic than triorganotin chlorides. These findings underline the importance of speciation effects on organotin interactions in the environment.

Candida↗
PubMed2000

Comparison of sodium tetraethylborate and sodium tetra(n-propyl)borate as derivatization reagent for the speciation of organotin and organolead compounds in water samples.

The influence of pH on the propylation with sodium tetra(n-propyl)borate of butyl- and phenyltins as well as for trimethyl- and triethyllead was investigated. Ethylation and propylation with tetraalkylborates were compared with regard to derivatization yields and figures of merit for organotin compounds in real water samples. Similar results for limit of detection (3-12 ng/L as tin), derivatization yield (40-100%) and relative standard deviation of the method (3-10%) were achieved for derivatization with the two tetraalkylborates. Propylation is thus the preferred method for the simultaneous determination of environmentally relevant organotin and organolead compounds. The handling of the hygroscopic and air sensitive reagents NaBEt4 and NaBPr4 was simplified by dissolving them in tetrahydrofurane. The reagent solutions in tetrahydrofurane can be stored for at least one month at 4 degrees C in the dark without observing any decrease in the derivatization efficiency.

Journal Article↗
PubMed1993

Comparison of flame ionization and inductively coupled plasma mass spectrometry for the detection of organometallics separated by capillary supercritical fluid chromatography.

Organotin compounds are separated by capillary supercritical fluid chromatography (SFC) and a comparison of the detection by flame ionization (FID) and inductively coupled plasma mass spectrometry (ICP-MS) is presented. Resolution, detection limits, linear dynamic range and reproducibility are the parameters compared between SFC-FID and SFC-ICP-MS, for the detection of tri- and tetraorganotin compounds. The resolution obtained in the SFC-FID system is not always observed in SFC-ICP-MS. Degradation in resolution is due to fluctuations in transfer line temperature. Baseline resolution for the organotins considered is achieved in both systems by using a longer column. Detection limits (DLs) are calculated as 3 sigma/S, where sigma is the standard deviation of the blank signal and S is the slope of the calibration curve. Detection limits of 10.3, 12.5, 12.0 and 9.0 pg are obtained for tetrabutyltin, tributyltin chloride, triphenyltin chloride and tetraphenyltin, respectively, using SFC-FID. An improvement in detection limits of one order of magnitude is achieved by SFC-ICP-MS for the same organotins (0.26, 0.80, 0.57 and 0.20 pg, respectively). The relative standard deviations using SFC-FID for five 50-nl injections, containing 0.5 ng Sn, ranged from 3.2 to 6.4%. Using SFC-ICP-MS, five replicate injections of 0.05 ng Sn give R.S.D.s from 1.3 to 3.4%.

Capillary Action↗
PubMed2003

Assessment of tin and butyltin species in estuarine superficial sediments from Gipuzkoa, Spain.

Ten superficial sediments from river estuaries of Gipuzkoa (North Spain) were collected and analyzed for nine metals (including tin, Sn) and butyltin compounds (monobutyltin, MBT; dibutyltin, DBT; tributyltin, TBT). Total metal concentration in the fine fraction (<63 micrometer) of the sediment was determined in aqua regia--hydrofluoric acid extracts by atomic absorption spectrometry. The butyltin species (BTs) were firstly extracted from the sediments with hydrochloric acid-methanol mixture. After derivatization with sodium tetraethyl borate, the organotin compounds were extracted by solid phase microextraction (SPME) in headspace mode. A fiber coated with 100 micrometer poly(dimethylsiloxane) was used for SPME. The organotin species were analyzed by gas chromatography-flame ionization detection. Analysis of the certified reference sediment (PACS-2) shown the suitability of the procedures for determination of metal contents and DBT-TBT species in contaminated sediments. Factorial analysis was used to examine the main sources of metals. Three factors represented more than 89% of the total variance of the metal system, and the Sn was related with Cu-Zn-Pb suggesting the same pollution source. The BTs concentrations in the area were high (TBT ranged from 0.05 to 5.48 mg Sn kg(-1)). The percentage of total butyltin species ( summation operator BTs) respect to the total Sn amount was higher than 4% in all the sediments, showing in the Bidasoa river estuary a remarkable value higher than 20%. Hence, the studied estuarine sediments reflect a pollution that is related with historical industrial and fishing activities of the area.

Environmental Monitoring↗
PubMed2002

Toxicity of tributyltin and triphenyltin to early life-stages of Paracentrotus lividus (Echinodermata: Echinoidea).

Sperm cell and embryo toxicity tests using the Mediterranean sea urchin Paracentrotus lividus were performed to assess the toxicity of tributyltin chloride, bis(tributyltin)oxide, triphenyltin acetate, and triphenyltin hydroxide. Toxicity values (mean effective concentration [EC50]) ranged from 2.97 to 18.5 microg/L for sperm cells and from 1.11 to 2.62 microg/L for embryos. For sperm cells, the toxicity of the two tributyl compounds was significantly greater than that of two triphenyl compounds; for embryos, the triphenyl compounds appeared to be more toxic. Study of embryotoxic effects highlighted closely concentration-dependent damages, the most sensitive stages corresponding to the crucial phases of differentiation (gastrula and prisma). Both EC50 and no-observed-effect concentration values for the four organotin compounds are similar to those reported in the literature for early life stages of other marine organisms.

Animals↗
PubMed1986

Effects of triorganotin-mediated anion-hydroxide exchange upon reconstituted cytochrome c oxidase proteoliposomes.

Proteoliposomes containing cytochrome c oxidase and an internally trapped fluorescent pH probe (pyranine) were used to monitor respiration-dependent internal alkalinization and membrane potential formation. A maximum steady-state pH gradient of about 0.4 pH unit (vesicle interior alkaline) was obtained during active respiration in presence of reducing substrates and cytochrome c. This pH gradient was abolished by the triorganotin compounds tripropyl-, tributyl-, and triphenyl-tin chloride. At the same time, the membrane potential, measured by carbocyanine dye uptake, was slightly increased in value. Valinomycin, which abolishes the membrane potential, restores the value of delta pH at low trialkyltin concentrations. The organotin compounds acted as electroneutral ionophores which exchanged intravesicular OH- ions with external SCN-, I-, and CI- ions, but not NO3- or SO4(2-) ions. Abolition of delta pH is accompanied by an increase in respiration rate, but full respiratory stimulation only occurs when both delta psi and delta pH are abolished by addition of both triorganotin and valinomycin. The triorganotin-valinomycin combination leads to active KCl accumulation by the respiring proteoliposome, and it is necessary to postulate an electrically neutral KCl efflux process to explain the continued steady respiration of the proteoliposomes in the presence of this ionophore combination.

Animals↗