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PubMed1986

Intravitreal chemotactic and mitogenic activity. Implication of blood-retinal barrier breakdown.

We produced breakdown of the blood-retinal barrier (BRB) in pigmented rabbits by several different mechanisms: retinal cryopexy, retinal laser, intravenous sodium iodate (30 mg/kg), or intravitreal injection of epinephrine (0.1 mL, 10(-3) M). The degree of BRB breakdown was monitored by computerized vitreous fluorophotometry. At 72 hours after treatment, rabbits were killed, and eyes were quickly removed, washed, and placed in liquid nitrogen. The vitreous was then carefully isolated free of contamination from other ocular tissues, homogenized, and aliquotted. For each sample we measured protein content, retinal pigment epithelial (RPE) cell chemotactic activity, and RPE mitogenic activity. Each of the above modalities produced significant breakdown of the BRB as measured by vitreous fluorophotometry and intravitreal protein concentration, while a pars plana intravitreal injection of saline (0.1 mL) did not. Vitreous from eyes treated with each of the above modalities caused significant stimulation of RPE migration (cryopexy, 684%; laser, 211%; sodium iodate, 480%; intravitreal epinephrine, 546%), while control vitreous and saline-injected vitreous caused only 89% and 77% stimulations, respectively. Similarly, vitreous from eyes treated with the above modalities caused significant stimulation of RPE proliferation (116% to 159%), while control vitreous caused only a 56% increase above baseline. Proliferative vitreoretinopathy, a disease process in which cellular migration and proliferation play important roles, occurs most commonly after surgical intervention. Breakdown of the BRB at the time of surgery may be a critical event due to intravitreal accumulation of serum-derived chemoattractants and mitogens.

Animals↗
PubMed1988

The role of breakdown of the blood-retinal barrier in cell-injection models of proliferative vitreoretinopathy.

Rabbits were given an intravitreous injection of 5.0 x 10(5) rabbit retinal pigment epithelial (RPE) cells, human RPE cells, or human dermal fibroblasts in one eye and an injection of vehicle alone in the other eye. Some rabbits were treated with retinal cryopexy or intravenous sodium iodate on the day before injection. Vitreous fluorophotometry (VFP) and fundus examinations were performed before and at various times after cell injections. Retinal detachments were graded by premortem ophthalmoscopic examinations and postmortem gross pathologic examinations. Eyes injected with cells had higher VFP readings than eyes injected with vehicle at all time points. Eyes injected with fibroblasts or rabbit RPE had significantly higher mean VFP values before the onset of retinal detachment than those injected with human RPE cells. Within each group, high levels of fluorescein leakage in the first week correlated well with severity of subsequent traction retinal detachment and the fibroblast and rabbit RPE groups had more severe detachments than the human RPE group. Treatment with cryopexy or sodium iodate resulted in higher VFP readings, a higher frequency of retinal detachments, and detachments that occurred earlier and that were more severe. These data demonstrate that intravitreous cells cause blood-retinal barrier breakdown in rabbits and that the amount and duration of this breakdown are important variables in retinal detachment formation.

Animals↗
PubMed1999

Iodine and disinfection: theoretical study on mode of action, efficiency, stability, and analytical aspects in the aqueous system.

Although they have been in use for nearly 170 years, the mode of action of iodine-based disinfectants is not yet clearly understood, as is manifested, for example, in diverging judgements about the relevance of the individual iodine species. Although studies based on calculated equilibrium concentrations in pure iodine solutions have already been done, there is a lack of knowledge about iodine solutions in the presence of additional iodide which would be of intrinsic importance for disinfection practice. Therefore, a re-calculation was undertaken considering variations of this parameter in the pH range 0-14. The presented calculations concern fresh iodine solutions not affected by disproportionation (iodate formation) and provide information about the equilibrium concentrations of the species I, I2, I3, I5-, I6(2-), HOI, O1-, HI2O-, IO2- and H2OI+. Additional iodide and the pH value have a very pronounced influence on the individual equilibrium concentrations (several powers of ten); hence, conditions can be indicated where the number of species of virtual importance is drastically reduced. In the most common case with iodine in the presence of additional iodide at pH < 6, only I-, I2 and I3- play a role. In the absence of additional iodide, at pH 8-9 and at high dilution (c(I2) < 10(-5) M), on the other hand, HOI accounts for over 90% of the oxidation capacity. At high iodide concentration (e.g., Lugol's solution) the species I5- and I6(2-) make up 8.2% of the oxidation capacity. The iodine cation H2OI+, frequently quoted as an active agent in disinfection, is without any relevance under the conditions occurring in practice, as are IO- and HI2O- which become important only at pH > 10. The stability problem (i.e. rate of iodate formation) arising at pH > 6 can be reduced to hypoiodous acid, as manifested in the simple rate law d[IO3]/dt = 0.25 [HOI]3/[H+] which allows an estimation of stability under weakly alkaline conditions. The results of this study allow us to deduce general qualities of aqueous iodine solutions, such as reactivity, stability, and analytical aspects, and to estimate major disinfection-orientated properties such as microbicidal activity, irritation, and incorporation effects. Though the calculations consider primarily preparations devoid of polymeric organic compounds capable of complexing iodine species, the results can be largely transferred to iodophoric preparations.

Disinfectants↗
PubMed1999

Iodine speciation in biological samples by capillary electrophoresis-inductively coupled plasma mass spectrometry.

A hyphenation of capillary electrophoresis (CE) to inductively coupled plasma mass spectrometry (ICP-MS) was employed for the speciation of iodine. The separation method used a buffer sandwich of phosphate (pH 2.3), NaOH, sodium dodecyl sulfate (SDS) and borate buffer (pH 8.3) for stacking, aiming at sufficient separation of iodide, iodate, thyroxine (T4) and triiodothyronine (T3). These four iodine species were separated within 15 min and subsequently detected during a pressure-driven detection step (baseline-separated) at 19.5, 29.1, 36.6 and 42.2 s. The detection limits were determined at 0.08 microg I/L (iodide), 0.3 microg I/L (iodate), 3.5 microg I/L (thyroxine) and 2.5 microg I/L (triiodothyronine). This method was applied on iodine speciation in human serum ("healthy" and after thyroid gland operation) and urine. The serum from the healthy person contained iodide (13 microg I/L), T4 (61 microg I/L) and T3 (7.5 microg I/L), whereas the serum from the thyroid-operated person lacked T3. As no "free" I-hormones are known in serum, the role of the thyroid hormone binding globulin (TBG) was investigated. We found that spiked T4 or T3 immediately bound to TBG. Investigations on human urine showed only a peak for iodide.

Electrophoresis, Capillary↗
PubMedDate not supplied

Iodine loss from iodised salt on heating.

Iodine deficiency disorders constitute a major public health problem in India. The national IDD control programme (NIDDCP) relies solely on iodine supplementation through fortification of common salt with potassium iodate. However, data regarding iodine loss due to high temperatures of cooking procedure is scarce. Using iodometric titration methods, we calculated iodine content of iodised salt samples subjected to incremental heat up to 350 degree Celsius. The results of the study indicate a gradual but minimal loss of iodine content from the iodised salt samples when subjected to high temperature with a maximum loss noticed being 18.5% at 350 degree Celsius. We conclude that there is minimal loss of iodine from the salt fortified with potassium iodate when subjected to heating (temperature normally attained during cooling process).

Administration, Oral↗
PubMed2006

Heme-thiolate haloperoxidases: versatile biocatalysts with biotechnological and environmental significance.

Heme-thiolate haloperoxidases are undoubtedly the most versatile biocatalysts of the hemeprotein family and share catalytic properties with at least three further classes of heme-containing oxidoreductases, namely, classic plant and fungal peroxidases, cytochrome P450 monooxygenases, and catalases. For a long time, only one enzyme of this type--the chloroperoxidase (CPO) of the ascomycete Caldariomyces fumago--has been known. The enzyme is commercially available as a fine chemical and catalyzes the unspecific chlorination, bromination, and iodation (but no fluorination) of a variety of electrophilic organic substrates via hypohalous acid as actual halogenating agent. In the absence of halide, CPO resembles cytochrome P450s and epoxidizes and hydroxylates activated substrates such as organic sulfides and olefins; aromatic rings, however, are not susceptible to CPO-catalyzed oxygen-transfer. Recently, a second fungal haloperoxidase of the heme-thiolate type has been discovered in the agaric mushroom Agrocybe aegerita. The UV-Vis adsorption spectrum of the isolated enzyme shows little similarity to that of CPO but is almost identical to a resting-state P450. The Agrocybe aegerita peroxidase (AaP) has strong brominating as well as weak chlorinating and iodating activities, and catalyzes both benzylic and aromatic hydroxylations (e.g., of toluene and naphthalene). AaP and related fungal peroxidases could become promising biocatalysts in biotechnological applications because they seemingly fill the gap between CPO and P450 enzymes and act as "self-sufficient" peroxygenases. From the environmental point of view, the existence of a halogenating mushroom enzyme is interesting because it could be linked to the multitude of halogenated compounds known from these organisms.

Amino Acid Sequence↗
PubMed2004

Single drop microextraction or solid phase microextraction-gas chromatography-mass spectrometry for the determination of iodine in pharmaceuticals, iodized salt, milk powder and vegetables involving conversion into 4-iodo-N,N-dimethylaniline.

A rapid sequence of oxidation and iodination using 2-iodosobenzoate as an oxidizing agent and N,N-dimethylaniline as an iodine scavenger at pH 6.4, when 4-iodo-N,N-dimethylaniline is formed, has been used for the determination of iodide by GC-MS. Solid phase microextraction (SPME) and single drop microextraction (SDME) have been used for the extraction of the iodo-derivative and their relative efficiencies compared. Pharmaceutical samples were subjected to solid phase extraction (SPE) for cleanup and the eluate analyzed for iodide. Iodate in salt samples was reduced to iodide with ascorbic acid. Milk powder and dried vegetables were wet combusted with peroxydisulfate to liberate covalently bound iodine as iodate which was reduced before derivatization. A rectilinear calibration graph was obtained for 0.1 microg-10 mg l(-1) iodide by both extraction methods, the correlation coefficient and limit of detection (LOD) were 0.9995 and 25 ng l(-1) iodide by SPME method, and 0.9998 and 10 ng l(-1) iodide by SDME method, respectively. SDME appeared to be more efficient technique than SPME for the present system. From the pooled data, the average recovery of spiked iodide to real samples was 100.7% (range 96.5-107.0%) with an average R.S.D. of 3.1% (range 2.6-4.5%).

Aniline Compounds↗
PubMed2004

Electrochemically modulated liquid chromatographic separations of inorganic anions.

Inorganic anion retention on a porous graphitic carbon (PGC) stationary phase is investigated by electrochemically modulated liquid chromatography (EMLC). Through various combinations of the potential applied (Eapp) to the PGC packing and/or changes in the composition (sodium salts of tetrafluoroborate, sulfate, and fluoride) and concentration (10, 25, and 50 mM) of an aqueous mobile phase, conditions for the separation of two different inorganic anion mixtures (iodate, bromide, nitrite, and nitrate or iodate, bromate, and chlorate) are developed. Results show that retention was affected by both variables, with the analyte retention factor, k', changing in a few cases by as much as a factor of ca. six. Moreover, plots of In k' are linearly dependent on both Eapp and In [SE], where [SE] is the supporting electrolyte concentration. Based on these findings, insights into the retention mechanism are briefly discussed by drawing on the theory for ion exchange chromatography.

Anions↗
PubMed2004

Effects of speciation on partitioning of iodine in aqueous biphasic systems and onto ABEC resins.

Polyethylene glycol (PEG)-aqueous biphasic systems (ABS) and PEG-grafted aqueous biphasic extraction chromatographic (ABEC) resins have been shown to remove inorganic species from environmental and nuclear wastes. The partitioning behavior of several iodide species (iodide, iodine, triiodide, iodate, and 4-iodo-2,6-dimethylphenol (I-DMP)) have been studied for PEG (MW 2000)-salt systems and ABEC resins. Iodide partitioning to PEG-rich phases or onto ABEC resins can be enhanced by derivatization with 2,6-dimethylphenol to form 4-iodo-2,6-dimethylphenol or by addition of I(2) to form triiodide. Conversely, iodide partitioning to the PEG-rich phase or onto ABEC resins is reduced by oxidation of iodide to IO(3)(-). Partitioning studies of iodide, iodate, and iodine in a PEG-ABS are compared to results using ABEC resins.

Hydrogen-Ion Concentration↗
PubMed2006

Octreotide in the treatment of lymphorrhea after renal transplantation: a preliminary experience.

BACKGROUND: Lymphorrhea is a minor complication after kidney transplantation but may develop into a lymphocele and prolong hospital stay. Treatment is conservative based on percutaneous drainage until lymphatic leakage cessation. It has been reported that octreotide has beneficial effects to treat lymphorrhea after axillary node dissection and excision of lymphatic malformations. The aim of this study was to report preliminary experience about octreotide treatment in lymphorrea after kidney transplantation. MATERIALS AND METHODS: This retrospective study included 20 recipients of cadaveric kidney allografts with posttransplant lymphorrhea including 10 treated with instillation of povidone iodate solution, and the other 10 with octreotide (0.1 mg three times a day subcutaneously). We reviewed the daily amount of fluid collection, duration of lymphorrhea, complications, lymphocele formation, rejection episodes, graft outcomes, and hospital stay. RESULTS: The average duration of lymphorrhea was 8.5 (+/-4.5) and 16.3 (+/-7.3) days for the octreotide versus the povidone groups, respectively (P = .001). No complications occurred among the octreotide group, while three lymphoceles grew among patients treated with povidone solution. No differences were observed for acute rejection episodes or renal function between the groups. No octreotide-related adverse events were noted. CONCLUSION: The mean length of lymphorrhea was lower with octreotide versus iodate povidone solution treatment. There was a shorter hospital stay and minor patient discomfort. In conclusion, lymphatic leakage after kidney transplantation may be successfully managed by octreotide administration.

Adult↗
PubMed2003

Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine.

Ozone is an excellent disinfectant and can even be used to inactivate microorganisms such as protozoa which are very resistant to conventional disinfectants. Proper rate constants for the inactivation of microorganisms are only available for six species (E. coli, Bacillus subtilis spores, Rotavirus, Giardia lamblia cysts, Giardia muris cysts, Cryptosporidium parvum oocysts). The apparent activation energy for the inactivation of bacteria is in the same order as most chemical reactions (35-50 kJ mol(-1)), whereas it is much higher for the inactivation of protozoa (80 kJ mol(-1)). This requires significantly higher ozone exposures at low temperatures to get a similar inactivation for protozoa. Even for the inactivation of resistant microorganisms, OH radicals only play a minor role. Numerous organic and inorganic ozonation disinfection/oxidation by-products have been identified. The by-product of main concern is bromate, which is formed in bromide-containing waters. A low drinking water standard of 10 microg l(-1) has been set for bromate. Therefore, disinfection and oxidation processes have to be evaluated to fulfil these criteria. In certain cases, when bromide concentrations are above about 50 microg l(-1), it may be necessary to use control measures to lower bromate formation (lowering of pH, ammonia addition). Iodate is the main by-product formed during ozonation of iodide-containing waters. The reactions involved are direct ozone oxidations. Iodate is considered non-problematic because it is transformed back to iodide endogenically. Chloride cannot be oxidized during ozonation processes under drinking water conditions. Chlorate is only formed if a preoxidation by chlorine and/or chlorine dioxide has occurred.

Animals↗
PubMed2005

Latex-coated polymeric monolithic ion-exchange stationary phases. 2. Micro-ion chromatography.

Latex-coated monolithic polymeric stationary phases are used for micro-ion chromatography (mu-IC) of inorganic anions. Monolithic columns were prepared by the in situ polymerization of butyl methacrylate, ethylene dimethacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid within fused-silica capillaries of varying internal diameters. Introduction of ion-exchange sites was achieved by coating the anionic polymeric monolith with either Dionex AS10 or Dionex AS18 quaternary ammonium functionalized latex particles to give total ion-exchange capacities in the range 9-24 nequiv for a 30-cm column. The resultant mu-IC columns were used for the separation of anionic analytes using chloride or acetate as the eluent-competing ion and direct UV spectrophotometric detection at 195 nm or using hydroxide as the eluent-competing ion and suppressed or nonsuppressed contactless conductivity detection. Separation efficiencies of 13,000 plates/m were observed (for iodate), and separation efficiency was maintained for large increases in flow rate (up to 42 microL/min, corresponding to a linear flow velocity of 18.5 mm/s), enabling highly reproducible, rapid separations to be achieved (seven analyte anions in less than 2 min). Use of a hollow fiber micromembrane suppressor enabled effective suppression of hydroxide eluents over the range 0.5-5.0 mM, thereby permitting suppressed conductivity detection to be performed. However, the relatively large size of the suppressor resulted in reduced separation efficiencies (e.g., 5400 plates/m for iodate). Detection limits obtained with suppressed conductivity detection were in the range 0.4-1.2 microM.

Journal Article↗
PubMed1998

Post-ion-chromatography derivatization for the determination of oxyhalides at sub-PPB levels in drinking water.

A new ion chromatographic method is presented that successfully determines iodate, chlorite, and bromate in drinking water at practical quantitation limits of 0.1, 0.4, and 0.2 microgram/L, respectively. Sample pretreatment is not required. The sensitivity of detection is enhanced by conversion of the eluting oxyhalides into the tribromide ion by a postcolumn reaction with bromide under acidic conditions. Spectrophotometric detection of the tribromide ion is at 267 nm. Optimization of the reaction conditions was studied, and the effective operating parameters are presented. The method detected significant levels of bromate in bottled water as well as low levels of iodate in tap water. All results were quality assured, and spike recoveries were in the range 94-110%. The method is applicable to a wide range of waters containing high levels of ions and organic carbon.

Chromatography, Ion Exchange↗
PubMed2006

Effect of bromide and iodide ions on the formation and speciation of disinfection byproducts during chlorination.

Two natural waters were fortified with various levels of bromide or iodide ions (0-30 microM) and chlorinated in the laboratory to study the impact of bromide and iodide ions on the formation and speciation of disinfection byproducts. Trihalomethanes (THMs), haloacetic acids (HAAs), total organic halogen (TOX), and its halogen-specific fractions total organic chlorine (TOCl), bromine (TOBr), and iodine (TOI), were measured in this work. The molar yields of THMs and HAAs increased as the initial bromide concentration increased. No significant change in TOX concentration was found for varying bromide concentrations. However, TOX concentrations decreased substantially with increasing initial iodide concentrations. At higher levels of bromide, there was a decreasing level of unknown TOX and unknown TOCl but an increasing level of unknown TOBr. The extent of iodine substitution was much lower than that of bromine substitution when comparing identical initial concentrations because a substantial amount of iodide was oxidized to iodate by chlorine. The tendency toward iodate formation resulted in the unusual situation where higher chlorine doses actually caused reduced levels of iodinated organic byproducts. Quantitative assessment of the results of this study showed a good agreement with kinetic data in the literature.

Acetic Acid↗
PubMed1997

Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer.

The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI right harpoon over left harpoon 2I(2) + IO(3)(-) + H(+) + 2H(2)O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H(+)] = 3.50, 4.00, 4.50, and 5.00, &mgr; = 0.50 M (NaClO(4)), and 25.0 degrees C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I(-); the iodide then reacts with HOI to give I(2). The reactive species (acetato-O)iodine(I), CH(3)CO(2)I, is postulated to increase the rate by assisting in the formation of I(2)O, a steady-state species that hydrolyzes to give HOIO and I(2). Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate(I), (CH(3)CO(2))(2)I(-), as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (lambda = 266 nm; epsilon = 530 M(-)(1) cm(-)(1)). The second process is proposed to be a disproportionation of HOIO to give IO(3)(-) and I(2). Above 1 M total buffer, the reaction becomes reversible with less than 90% I(2) formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.

Journal Article↗
PubMed1999

Crystal morphology prediction and morphology variation in NaIO4 and NaIO4.3H2O.

Attachment energies computed with only Coulomb potentials have been utilized to predict crystal morphologies for NaIO(4), sodium iodate, and the hydrate NaIO(4).3H(2)O, sodium iodate trihydrate [actually Na(H(3)O)(IO(3))(OH)(3)]. As with other previously studied water-soluble ionic compounds, these two systems exhibit a systematic relationship between the early growth morphology and that of mature crystals; this relationship can in each case be reproduced by adjusting one attachment energy value. Morphology prediction for these two substances is of particular interest because NaIO(4).3H(2)O is a polar crystal and involves extensive hydrogen bonding, and because obtaining the observed morphology for NaIO(4) involved consideration of solvent desorption at the growing faces.

Journal Article↗
PubMed1976

Conductance of the sodium channel in myelinated nerve fibres with modified sodium inactivation.

1. Na current fluctuations in nodes of Ranvier were measured under voltage clamp conditions as described in the preceding paper (Conti, Hille, Neumcke, Nonner & Stämpfli, 1976) and analysed in terms of power spectral density calculated for frequencies between 30 Hz and 5 kHz. 2. External (10(-5) g/ml.) Leiurus scorpion venom or Anemonia Toxin II (3 X 10(-5) g/ml.) or internal 20 mM iodate were applied in order to remove or slow down inactivation in part of the Na channels. The treatment increased the steady-state Na current during the noise measurement one-to eight fold over that in normal fibres. 3. Noise spectra were interpreted as the sum of 1/f noise and noise SNa(f) due to all-or-none, open-close transitions of single Na channels. The drug effects on the inactivation could be accounted for either by assuming two populations of channels, one with and one without inactivation, or by postulating a single population with modified inactivation characteristics. 4. Except for an increase in amplitude, the fluctuation spectra SNa(f) were similar to the ones in normal nodes. Again, the time constants taum obtained from the fit of the spectra agreed within a factor of 2 with the values of taum found in the macroscopic Na currents. 5. From the fluctuation spectra, single Na channel conductances gamma of 5-4 +/- 0-4 pS (iodate), 6-7 +/- 0-5 pS (Leiurus) and 7-0 +/- 0-6 pS (Anemonia) were calculated. The value of gamma was not significantly voltage dependent. 6. Our observations indicate that inactivation of Na channels can be modified with at most small effects on the microscopic properties of the activation process and on the conductance of the open channel. They suggest that the h mechanism normally produces all-or-none, open-close changes of conductance.

Animals↗
PubMed1988

Characterization of voltage-gated sodium channels in ovine gonadotrophs: relationship to hormone secretion.

1. The properties of whole-cell Na+ currents (INa) were studied in immunocytochemically identified ovine gonadotrophs using the patch clamp technique. 2. Voltage recording under current clamp revealed that gonadotrophs did not fire spontaneously, and fired only a single action potential in response to a depolarizing current clamp step. 3. Under voltage clamp, INa was found to be sensitive to tetrodotoxin (TTX) and had an activation threshold of about -75 mV, with peak current occurring at -20 to -30 mV. 4. Using a two-pulse protocol a delay in the onset of inactivation was observed, suggesting that inactivation is dependent on and preceded by the activation phenomenon. 5. Kinetics of recovery from inactivation of the Na+ channels were studied with test pulses applied at various times after a depolarizing pre-pulse. Recovery from inactivation showed an initial delay, in contrast to the predictions of the Hodgkin-Huxley equations. 6. Recovery from inactivation was examined by using a repetitive pulse protocol, showing approximately 1 s is required for the channels to achieve a 95% recovery. 7. The steady-state inactivation (h infinity -V) curve was sigmoidal and fitted by a logistic growth curve model. The half-inactivation value of the Na+ current occurred at a membrane potential of -70 +/- 8 mV. 8. Noise power spectra derived from fluctuations of INa could be fitted with a single Lorentzian function, and the time constant value was slower at more depolarizing potentials. 9. The single-Na+-channel conductance was estimated from fluctuation analysis under conditions of reduced Na+ current amplitude by depolarizing pre-pulses. The single-channel conductance derived by the above method (approximately equal to 11 pS) corresponded to the single-channel conductance derived from single-channel current measurements using the outside-out version of the patch clamp technique (approximately equal to 13 pS). 10. Inactivation of INa was slowed by including 15 mM-iodate in the pipette. Ensemble fluctuation analysis of INa under these conditions was carried out using the steady state portion of the inactivation phase of the modified INa records, revealing a process best fitted by a double Lorentzian power spectrum, consistent with inactivation kinetics involving both a fast and a slow process. The time constant values correlated well with those obtained from a double-exponential fit to the decaying inactivation phase of the iodate-modified INa.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗