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1.
The influence of longwave ultraviolet radiation (u.v.-A) on the photosynthetic activity (14C-assimilation) of phytoplankton 总被引:1,自引:0,他引:1
The impact of u.v.-A (315400 nm) on phytoplanktonic C-assimilationhas been studied in situ and in the laboratory under artificiallight. Water samples from Lake Lucerne were placed in DURAN-glassbottles and incubated either covered or uncovered with u.v.absorbing transparent tubes. Exposure to u.v.-A clearly inhibited14C-assimilation in the uncovered samples both in situ and inthe laboratory. Variations in visible light intensity and filteringof u.v.-B selectively demonstrated small inhibition of 14C-assimilation.U.v.-A inhibition of productivity is the major factor in thewell known depression in productivity for surface waters. 相似文献
2.
A method developed to quantify taste buds in living human subjectsto study the relationship between taste sensitivity and tastebud distribution was used to count the taste buds in 10 humansubjects; fungiform papillae were mapped in 12 subjects. Tastebuds were identified by staining taste pores with methyleneblue, and images of the papillae and their taste pores wereobtained with videomicroscopy and an image processor. Fungiformpapillae showed a 3.3-fold range in density, from 22.1 to 73.6papillae/cm2 with an average of 41.1 ± 16.8/cm2 (s.d.,n = 2). There was a 14-fold range in taste pore density, from36 to 511 pores/cm2 among subjects, with an average of 193 ±133/cm2 (s.d., n = 10). Fungiform papillae contained from 0to 22 taste pores, with an average per subject of 3.75 ±1.4 taste pores/papilla (s.d., n = 10). We hypothesize thatsome differences in human taste sensitivity may be related tothese variations in taste bud density. 相似文献
3.
The marine diatoms Lauderia annulata and Synedra planctonicaharvested during exponential growth were exposed to differentdoses of u.v.-B (286, 439 and 710 J m2 d1) for2 days. Uptake of 15N-nitrate was estimated before, during andafter u.v.-B radiation over 2 days. Exposure to high levelsof u.v.-B (710 J m2 d1) caused irreversible damageat the second daily irradiance. Lauderia cells were less affectedby u.v.-B stress than Synedra cells. 15N-nitrate uptake wasreduced under u.v.-B irradiance but could be reactivated within1 day following exposure to a low dose (286 J m2 d1).Higher levels of u.v.-B radiation (710 J m2 d1)led to irreversible damage. The pattern of 15N-incorporationinto several amino acids of Lauderia varied after 2 days ofu.v.-B radiation. 15N enrichment of glutamine increased markedlyafter u.v.-B stress (717 J m2 d1) whereas I5Nexcess of aspartic acid was significantly reduced. Results arediscussed with reference to the u.v.-B damage of the nitratetransport system. 相似文献
4.
Nuclei were isolated from cotyledons of a range of accessionsfrom 14 species of Glycine. These were stained with ethidiumbromide and the relative fluorescence for each genotype wasmeasured by flow cytometry. The DNA content was estimated bycomparison of relative fluorescence with that from nuclei fromseedling leaves of Allium cepa, whose DNA content has been calculatedpreviously by chemical assay. The 4C amounts for diploid Glycineranged from 3.80 to 6.59 pg. Two groups of diploid species appearedfrom the analysis. The first consisted of species with amountsranging from 3.80 to 5.16 pg and included G. canescens (AA),G. argyrea (A1 A1), G. clandestina (A2A2), G. microphylla(BB),G. latifolia (B1B1), G. tabacina 2n=40 (B2B2), G. tomentella2n=38 (EE) and 2n=40 (DD), G. max and G. soja (GG), G. arenariaand G. latrobeana. A second group had higher DNA contents rangingfrom 5.27 to 6.59 pg, and consisted of G. curvata, G. cyrtoloba(CC), and G. falcata (FF). The polyploid species, G. tabacina2n=80 (AABB, BBB1B1), G. tomentella 2n=78 and 2n=80 (AAEE andDDEE, respectively) contained amounts approximating to the sumsof the respective parental diploid species thought to have givenrise to these allotetraploids. Intraspecific variation was detectedin the DNA content of G. canescens. Within the overall distributionof DNA amounts found in A genome species, each genome containeda range of DNA contents specific to that species. This phenomenonwas also detected amongst B genome species. 相似文献
5.
Kaarina Sivonen 《Hydrobiologia》1982,86(1-2):165-170
Odour production by actinomycete (Streptomyces spp.) strains isolated from hypereutrophic natural waters in which muddy odours in fish have occurred, were studied by the ISP (International Streptomyces Project) carbon utilization method. The streptomycete strains were isolated from water, bottom mud and aquatic plants. Nine different carbon sources were used. Odour character was determined by sniffing the cultures. Odour production varied depending on the strain and the carbon source used. Some of the strains produced similar odours in all media regardless of the carbon source. In other strains, the odour varied depending on the carbohydrate used. The total colony counts of actinomycetes may not necessarily indicate the role of actinomycetes in odour problems in the aquatic environment because the odour production by actinomycetes depends on environmental factors. 相似文献
6.
By manipulation of various growth regulators and physical conditions,plants have been regenerated from excised roots, stem segments,cotyledons, leaves, and callus cultures of red cabbage (Brassicaoleracea var. capitata) grown under in vitro conditions. Shootbuds were induced on isolated root segments (1 cm long) culturedon Murashige and Skoog's medium and the frequency of bud formationwas greatly enhanced by the addition of kinetin (0.5 part 106).Callus obtained from the seeds, cotyledons, and hypocotyl segmentscultured on a medium fortified with 2,4-D (1 part 106),kinetin (0.1 part 106), and coconut milk (10%, v/v) hasbeen repeatedly subcultured. The callus is slow growing, andon transference to a kinetin (2 parts 106) and IAA (2parts 106) medium underwent morphogenesis to give riseto plants. The significance of the propagation of red cabbageby in vitro culture is pointed out. 相似文献
7.
Suspension cultures of Stizolobium hassjoo cells were cultivated in a 7l bioreactor. The growth rate and intracellular L-DOPA content of the cells using two different turbine impellers were compared. There were distinct differences in growth behavior and L-DOPA productivity in the range of 100 to 500 rpm for flat-blade turbine impeller. Disk turbine retarded significantly the cell growth but not so significantly for L-DOPA production in the range of 200 to 300 rpm. The shear force intensity of the two impellers at various rotational rates was compared with shear force index (SFI), and power input per unit mass and eddy length scale. There was good consistency among the three indexes for shear force intensity. Thus with SFI the shear force intensity of bioreactor can be indirectly estimated. A critical shear stress that may cause sublytic effect in cells was identified for flat-blade turbine operated at 400 rpm. The common effect between the shear stress and the proton elicitation in the bioreactor was elucidated with a hypothesis of signal transduction by second messenger, H+. Our results suggested that H+ transduced the signal to protoplast when S. hassjoo cells were stimulated by shear stress. This resulted in an increase of H+ which triggered a similar reaction to the pH control of culture broth and enhanced the L-DOPA production. 相似文献
8.
9.
An intensity/time study of the taste of selected amino acidswas carried out. Intensity, persistence and total gustatoryresponse were assessed at five concentrations. Ten amino acidswere assessed for sweetness and eleven amino acids were assessedfor bitterness, four amino acids being assessed for both sweetnessand bitterness. Both a linear function and a power function,I = Kcn (where I is taste intensity, c is concentration, K isa constant and n is the exponent of taste intensity), were fittedto the data. The accession efficiencies for taste recognitionand taste detection were found. Kinetic equations were usedto find Km, the affinity of the receptor site for the sapidmolecule. Limited relationships between chemical structure ofthe amino acids and their temporal properties were found. 相似文献
10.
During the spring of 1994, we determined the factors responsiblefor the decline of the seasonal diatom bloom in the Gullmarfjord, on the west coast of Sweden. Four species constituted>75% of the biomassDetonula confervacea, Chaetocerosdiadema, Skeletonema costatum and Thalassiosira nordenskioeldiireachingconcentrations of 4900, 350, 8200 and 270 cells ml1,respectively. Growth of phytoplankton was exponential (growthrate = 0.12 day1) from 3 to 21 March, after which a galewith winds >15 m s1 caused massive aggregation. Amaximum of 130 p.p.m. (v/v) of marine snow aggregates was observedby in situ video at the peak of the bloom. Critical concentrations(Jackson, Deep-Sea Res., 37, 11971211, 1990) were similarto observed showing that coagulation theory could explain thesudden decline of the bloom. The heterotrophic dinoflagellateGyrodinium cf. spirale increased exponentially after the peakof the bloom with maximum (temperature-adjusted) growth rates.After the rapid aggregation and sedimentation of the bloom,they were able to control any further growth of diatoms. Nitrateand silicate were never depleted, but phosphate may have beenlimiting by the end of the study period. We conclude that massaggregation during a gale marked the end of the bloom, and thatintense grazing by heterotrophic dinoflagellates prevented anysubsequent increase of diatoms. 相似文献
11.
A Cl channel and two types of K+ channel have been observed,by the use of the patch-clamp technique, in the membrane surroundingcytoplasmic droplets from Chara corallina. Measurements on cell-attachedpatches showed that the channel selective for Cl hada chord conductance of 21 pS at the resting membrane p.d. (mean= 11 mV, n = 19) and when open, passed an outward current of1.4 pA (n = 24 patches) at the resting p.d., with reversal ofthe direction of current at 54 mV (130 mol m3Cl in the external solution). The Cl concentrationin the cytoplasmic droplet calculated from the reversal p.d.was 15 mol m3. The channel strongly rectified outwardcurrent flow, but this rectification disappeared with symmetricalCl concentrations across detached patches of membrane.It is concluded that rectification observed in cell-attachedpatches is primarily due to asymmetric Cl concentrationsrather than an asymmetry in energy barriers to Cl permeationin the channel or any voltage-dependent kinetics of the channel.The channel was rarely observed in detached patches despitebeing commonly observed in cell-attached patches. However, theabsence of Ca2+ at the cytoplasmic face of the membrane allowedobservation of the channel in detached patches for brief periods,during which ion substitution experiments revealed a permeabilitysequence of aspartate (76:33:1). A 100 pS K+ channel previously described by Luhring (1986) wasfrequently observed, in some instances simultaneously, witha channel having a conductance of 60 pS and displaying outwardrectification. This rectification was due to the channel remainingopen almost continuously for positive membrane potential differences(p.d.) and remaining shut almost continuously for negative p.d.'s.The 60 pS channel, like the 100 pS K+ channel, reversed currentflow at the resting p.d., suggesting that it was also permeableto K+. Key words: Plant ion-channels, chloride channel, potassium channel, patch-clamp 相似文献
12.
A role for ERK1/2 in EGF- and ATP-dependent regulation of amiloride-sensitive sodium absorption 总被引:3,自引:0,他引:3
Falin R Veizis IE Cotton CU 《American journal of physiology. Cell physiology》2005,288(5):C1003-C1011
Receptor-mediated inhibition of amiloride-sensitive sodium absorption was observed in primary and immortalized murine renal collecting duct cell (mCT12) monolayers. The addition of epidermal growth factor (EGF) to the basolateral bathing solution of polarized monolayers reduced amiloride-sensitive short-circuit current (Isc) by 1525%, whereas the addition of ATP to the apical bathing solution decreased Isc by 4060%. Direct activation of PKC with phorbol 12-myristate 13-acetate (PMA) and mobilization of intracellular calcium with 2,5-di-tert-butyl-hydroquinone (DBHQ) reduced amiloride-sensitive Isc in mCT12 monolayers by 46 ± 4% (n = 8) and 22 ± 2% (n = 8), respectively. Exposure of mCT12 cells to EGF, ATP, PMA, and DBHQ caused an increase in phosphorylation of p42/p44 (extracellular signal-regulated kinase; ERK1/2). Pretreatment of mCT12 monolayers with an ERK kinase inhibitor (PD-98059; 30 µM) prevented phosphorylation of p42/p44 and significantly reduced EGF, ATP, and PMA-induced inhibition of amiloride-sensitive Isc. In contrast, pretreatment of monolayers with a PKC inhibitor (bisindolylmaleimide I; GF109203x; 1 µM) almost completely blocked the PMA-induced decrease in Isc, but did not alter the EGF- or ATP-induced inhibition of Isc. The DBHQ-mediated decrease in Isc was due to inhibition of basolateral Na+-K+-ATPase, but EGF-, ATP-, and PMA-induced inhibition was most likely due to reduced apical sodium entry (epithelial Na+ channel activity). The results of these studies demonstrate that acute inhibition of amiloride-sensitive sodium transport by extracelluar ATP and EGF involves ERK1/2 activation and suggests a role for MAP kinase signaling as a negative regulator of electrogenic sodium absorption in epithelia. mitogen-activated protein kinase; epithelial ion transport; epithelial sodium channel 相似文献
13.
CAMPBELL A. W.; GRIFFIN W. B.; CONNER A. J.; ROWARTH J. S.; BURRITT D. J. 《Annals of botany》1998,82(1):29-33
Triticum aestivumxZea mayscrosses are now widely used in theproduction of wheat doubled haploids to produce homozygous lines.Seasonal effects are known to influence the number of haploidembryos produced through wheatxmaize crosses, but the effectsof temperature and light have not been quantified. This studyinvestigated the effect of temperature and light intensity onhaploid embryo production. New Zealand wheat cultivars weregrown in a glasshouse until booting when they were transferredto growth cabinets at three temperatures (day/night; 17/12,22/17 or 27/22 °C at an irradiance of 250 µmol m-2s-1PAR).In another experiment, wheat lines were transferred to a growthcabinet at one of three light intensities (300, 500 or 1000µmol m-2s-1PAR at 22/17 °C day/night, with a photoperiodof 16 h). The temperature and light intensity at which pollinationswere made and subsequent fertilisation and embryo developmentoccurred, significantly (P<0.01) influenced the frequencyof haploid embryo production. The optimal temperature for embryorecovery was 22/17 °C. The greatest number of embryos wasproduced at a light intensity of 1000 µmol m-2s-1. Thesefindings will result in improvements in the overall efficiencyof the wheatxmaize system for wheat doubled haploid production.Copyright1998 Annals of Botany Company Intergeneric crossing, temperature, light intensity,Triticum aestivum,wheat,Zea mays,maize. 相似文献
14.
Guard cell protoplasts were isolated enzymatically from theepidermis of Vicia faba L. and their photosynthetic activitieswere investigated. Time courses of light-induced changes inthe chlorophyll a fluorescence intensity of these protoplastsshowed essentially the same induction kinetics as found formesophyll protoplasts of Vicia. The transient change in thefluorescence intensity was affected by DCMU, an inhibitor ofphotosystem II; by phenylmercuric acetate, an inhibitor of ferredoxinand ferredoxin NADP reductase; and by methyl viologen, an acceptorof photosystem I. Low temperature (77 K) emission spectra ofthe protoplasts had peaks at 684 and 735 nm and a shoulder near695 nm. A high O2 uptake (175 µmol mg1 Chl hr1)was observed in guard cell protoplasts kept in darkness, whichwas inhibited by 2 mM KCN or NaN3 by about 60%. On illumination,this O2 uptake was partially or completely suppressed, but itssuppression was removed by DCMU, which indicates that oxygenwas evolved (150 µmol mg1 Chl hr1) photosynthetically.We concluded that both photosystems I and II function in guardcell chloroplasts and that these protoplasts have high respiratoryactivity. (Received January 30, 1982; Accepted May 15, 1982) 相似文献
15.
Pacemaker activity in urethral interstitial cells is not dependent on capacitative calcium entry 总被引:6,自引:0,他引:6
Bradley E Hollywood MA McHale NG Thornbury KD Sergeant GP 《American journal of physiology. Cell physiology》2005,289(3):C625-C632
The aim of the present study was to investigate the properties and role of capacitative Ca2+ entry (CCE) in interstitial cells (IC) isolated from the rabbit urethra. Ca2+ entry in IC was larger in cells with depleted intracellular Ca2+ stores compared with controls, consistent with influx via a CCE pathway. The nonselective Ca2+ entry blockers Gd3+ (10 µM), La3+ (10 µM), and Ni2+ (100 µM) reduced CCE by 67% (n = 14), 65% (n = 11), and 55% (n = 9), respectively. These agents did not inhibit Ca2+ entry when stores were not depleted. Conversely, CCE in IC was resistant to SKF-96365 (10 µM), wortmannin (10 µM), and nifedipine (1 µM). Spontaneous transient inward currents were recorded from IC voltage-clamped at 60 mV. These events were not significantly affected by Gd3+ (10 µM) or La3+ (10 µM) and were only slightly decreased in amplitude by 100 µM Ni2+. The results from this study demonstrate that freshly dispersed IC from the rabbit urethra possess a CCE pathway. However, influx via this pathway does not appear to contribute to spontaneous activity in these cells. smooth muscle; patch clamp; spontaneous transient inward currents 相似文献
16.
Regulation of intracellular Ca2+ release in corpus cavernosum smooth muscle: synergism between nitric oxide and cGMP 总被引:1,自引:0,他引:1
Williams BA Liu C Deyoung L Brock GB Sims SM 《American journal of physiology. Cell physiology》2005,288(3):C650-C658
Tonic contraction of corpus cavernosum smooth muscle cells (SMCs) maintains the flaccid state of the penis, and relaxation is initiated by nitric oxide (NO), leading to erection. Our aim was to investigate the effect of NO on the smooth muscle cellular response to adrenergic stimulation in corpus cavernosum. Fura-2 fluorescence was used to record intracellular Ca2+ concentration ([Ca2+]i) from freshly isolated SMCs from rat and human. Phenylephrine (PE) transiently elevated [Ca2+]i in the presence and absence of extracellular Ca2+, indicating release from intracellular stores. Whereas the NO donor S-nitroso-N-acetylpenicillamine (SNAP) with sildenafil citrate (SIL) caused no change in basal [Ca2+]i, the PE-induced rise of [Ca2+]i was reversibly inhibited by 27 ± 7% (n = 21, P < 0.005) in rat and by 55 ± 15% (n = 9, P < 0.01) in human SMCs. SNAP and SIL also reduced the contractile response to PE. To investigate the mechanism, we applied mediators alone or in combination. The soluble guanylyl cyclase inhibitor ODQ reduced the effect of SNAP and SIL. SIL, cGMP analogs, and NO donors without SIL did not reduce the PE-induced rise of [Ca2+]i. However, the combination of 8-bromo-cGMP with SNAP reduced the Ca2+ peak by 42 ± 9% (n = 22, P < 0.01). Our results demonstrate that NO and cGMP act synergistically to reduce Ca2+ release from intracellular stores. Reduction of intracellular Ca2+ release may contribute to relaxation of the corpus cavernosum, leading to erection. calcium stores; nitric oxide; sildenafil citrate; inositol 1,4,5-trisphosphate receptor 相似文献
17.
Hansen, A. P., Pate, J. S. and Atkins, C. A. 1987. Relationshipsbetween acetylene reduction activity, hydrogen evolution andnitrogen fixation in nodules of Acacia spp.: Experimental backgroundto assaying fixation by acetylene reduction under field conditions.J.exp. Bot. 38: 112 Glasshouse grown, symbiotically-dependent seedlings of Acaciaalata R.Br., .A. extensa Lindl., and A. pulchella R.Br. wereexamined for acetylene reduction in closed assay systems usingundisturbed potted plants, excavated whole plants, nodulatedroots or detached nodules. Nitrogenase activity declined sharplyover the first hour after exposure of detached nodules to acetylene(10% v/v in air), less steeply or not at all over a 3 h periodin assays involving attached nodules. Using detached nodules,rates of acetylene reduction, nitrogen (15N2) fixation, andhydrogen evolution in air (15N2) and acetylene-containing atmosphereswere measured in comparable 30 min assays. Total electron flowthrough nitrogenase in air was determined from rates of nitrogen(15N2) fixation ( ? 3) plus hydrogen evolution, that in thepresence of acetylene from rates of acetylene reduction andhydrogen evolution in air: acetylene. Values for the ratio ofelectron flow in air: acetylene to that in air ranged from 0?43to 0?83 in A. pulcheila, from 0?44 to 0?66 in A. alala and from0?37 to 0?70 in A. extensa, indicating substantial inhibitionof electron flow through nitrogenase of detached nodules byacetylene. Relative efficiencies of nitrogenase functioningbased on hydrogen evolution and acetylene reduction were from0?15 to 0?79, those based on nitrogen (15N2) fixation and hydrogenevolution from 0?53 to 0?87. Molar ratios of acetylene reducedto nitrogen (15N2) fixed were 2?82 ? 0?24, 201 ? 0?15, and 1?91? 0?11 (?s.e.; n = 7) for A. pulcheila,A. extensa and A. alata respectively A standard 510 min acetylene reduction assay, conductedon freshly detached unwashed nodules in daytime (12.0014.00h), was calibrated for field use by comparing total N accumulationof seedlings with estimated cumulative acetylene reduction overa 7-week period of glasshouse culture. Molar ratios for acetylenereduced: nitrogen fixed using this arbitrary method were 3?58for A. alata, 4?82 for A. extensa and 1?60 for A. pulchella.The significance of the data is discussed. Key words: Acacia spp, nitrogenase functioning 相似文献
18.
Aqueous foliar sprays of N-dimethylaminosuccinamic acid (daminozide)at 2000 p.p.m. and gibberellic acid (GA) at 100 p.p.m. wereapplied 45, 59, 82 and 100 days after sowing to Chantenay carrotswith population densities of 244, 495 and 883 plants m2.The plants were harvested on ten approximately weekly occasions;fresh weights were determined and d. wt estimates were obtainedfor the separated shoots (s) and roots (r). Allometric linearregressions of the logarithm of s on that of r at each harvestseparately, clearly showed that GA always increased shoot: rootratio and reduced root yield (by approximately 35 per cent)but could sometimes also increase whole-plant weight. Daminozideincreased root yield (by approximately 7 per cent from 80 tonnesha1) and tended to have effects opposite to those ofGA. Daucus carota L., carrot, root weight, shoot weight, N-dimethylaminosuccinamic acid (daminozide), gibberellic acid 相似文献
19.
Reconstitution and Characterization of H+-Translocating ATPase from the Plasma Membrane of Phaseolus mungo L. Roots 总被引:1,自引:0,他引:1
Plasma membrane H+-translocating ATPase was partially purifiedfrom mung bean (Phaseolus mungo L.) roots and reconstitutedinto soybean phospholipid (asolectin) liposomes by the n-octylglucosidedilution method. The resulting proteoliposomes were mainly unilamellarvesicles ranging in size from 0.05 to 0.2 µm. The existenceof ATP-drived H+-pumping across the proteoliposomes was demonstratedby the quenching of quinacrine fluorescence in the presenceof Mg2+. The quenching could be abolished by an uncoupler, FCCP,and an inhibitor of H+-translocating ATPase, vanadate. The reconstitutedATPase consisted of three major polypeptides of 105 KDa, 67KDa and 57 KDa. Its pH optimum, divalent cation stimulationand vanadate sensitivity were similar to those of partiallypurified ATPase. However, the specificity toward ATP was muchgreater following reconstitution. Also reconstitution reducedthe degree of inhibition by DCCD. Local anesthetics (e.g. dibucaine)had no effect on H+-pumping activity but increased the ATPaseactivity when proteoliposomes were reconstituted in their presence. (Received May 2, 1986; Accepted October 17, 1986) 相似文献
20.
Airway surface fluid volume and Cl content in cystic fibrosis and normal bronchial xenografts 总被引:1,自引:0,他引:1
We describe theuse of an in vivo human bronchial xenograft model of cystic fibrosis(CF) and non-CF airways to investigate pathophysiological alterationsin airway surface fluid (ASF) volume (Vs) and Cl content.Vs was calculated based on thedilution of an impermeable marker,[3H]inulin, duringharvesting of ASF from xenografts with an isosmotic Cl-free solution.These calculations demonstrated thatVs in CF xenographs (28 ± 3.0 µl/cm2;n = 17) was significantly less thanthat of non-CF xenografts (35 ± 2.4 µl/cm2;n = 30). The Cl concentration of ASF([Cl]s) wasdetermined using a solid-state AgCl electrode and adjusted for dilutionduring harvesting using the impermeable[3H]inulin marker.Cumulative results demonstrate small but significant elevations(P < 0.045) in[Cl]s in CF (125 ± 4 mM; n = 27) compared with non-CF(114 ± 4 mM; n = 48) xenografts.To investigate potential mechanisms by which CF airways may facilitatea higher level of fluid absorption yet retain slightly elevated levelsof Cl, we sought to evaluate the capacity of CF and non-CF airways toabsorb both 22Na and36Cl. Two consistent findings wereevident from these studies. First, in both CF and non-CF xenografts,22Na and36Cl were always absorbed in anequal molar ratio. Second, CF xenografts hyperabsorbed (~1.5-foldhigher) both 22Na and36Cl compared with non-CFxenografts. These results substantiate previously documented findingsof elevated Na absorption in CF airways and also suggest that theslightly elevated[Cl]s found in thisstudy of CF xenograft epithelia does not occur through a mechanism ofdecreased apical permeability to Cl. 相似文献