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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied lung explants in submersion organ culture to examine the role of the developing fetal alveolar epithelium in the production of lung fluid. Fourteen-day-gestation fetal rat lungs were grown in a collagen gel matrix supplemented with F-12 media and 10% fetal calf serum. In this model, the lung continues to grow, secrete fluid, and become progressively cystic in morphology. There is gradual thinning of the distal epithelial layer, which is lined by alveolar type II cells and their precursors. After 6 to 8 days in culture, we impaled the cyst walls with a microelectrode and continuously recorded the transepithelial potential (psi t). Stable, baseline transepithelial potentials of -1.1 to -6.2 mV (mean +/- SEM = -3.3 +/- 0.11 mV, lumen negative, n = 34) were measured in bicarbonate-buffered Ringer's solution, suggesting active electrolyte transport. When bumetanide, an inhibitor of chloride secretion in other systems, was added to the bathing solution, psi t decreased from a baseline of -3.5 +/- 0.07 mV (mean +/- SEM) to a value of -2.2 +/- 0.07 mV, suggesting chloride transport contributes to the voltage (n = 18, P less than 0.0005). Isoproterenol hyperpolarized psi t from a baseline of -4.3 +/- 1.0 mV to -6.5 +/- 1.0 mV (n = 7, P less than 0.005). 8-(4-Chlorophenylthio) adenosine 3':5'cyclic monophosphate (CPT-cAMP) plus isobutylmethylxanthine (IBMX) similarly hyperpolarized psi t from a baseline of -4.6 +/- 0.4 mV to -7.3 +/- 0.7 mV (n = 11, P less than 0.005). Addition of bumetanide after stimulation with isoproterenol or CPT-cAMP/IBMX depolarized psi t.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1992 Jun
PMID:Secretion of lung fluid by the developing fetal rat alveolar epithelium in organ culture. 131 92

Fertilizing competency of multiple ovulated eggs in the domestic fowl was examined by fertilization in vitro and early development in culture. Normal laying hens (White Leghorn) were treated with 75 IU of PMSG for 7 days followed by injection of anterior pituitary extracts from chickens (CAPE). Ovulation began to occur 7.5 h after injection of CAPE. These hens ovulated 1-7 ova but some premature ovulation of GV stage ova were observed. In vitro fertilization of the multiple ovulated ova was examined by inseminating 10(6)-10(7) sperm onto the germinal disks in m-Ringer's solution. The gamete or zygote nuclei were detected by DNA specific fluorescence using DAPI (4',6'-diamidino-2-phenylindole) in the histological section prepared from the germinal disk. Process of fertilization was examined in the eggs incubated for 4 h after insemination in DMEM + liquid albumen at 41 degrees C under the atmosphere of 5% CO2 in air. Fertilization rate of the total multiple ovulated eggs was 55% (11/20), in which 90% (9/10) and 10% (1/10) in the eggs recovered 7.5-8.5 h and 9.0-9.5 h after CAPE injection were obtained, respectively. Normal pronuclei were formed in five eggs of those recovered 7.5-8.5 h after CAPE injection. Early development after fertilization in vitro was also examined by incubation for 12 h in DMEM + liquid albumen at 41 degrees C under the atmosphere of 5% CO2 in air. Although development in vitro was delayed compared to that in utero condition, normal development was observed in naturally and multiple ovulated eggs.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1991 Feb
PMID:Fertilizing competency of multiple ovulated eggs in the domestic fowl (Gallus domesticus). 200 27

A silk suture in the urinary bladder of rats induces tumorous growths of urothelia. Whether these tumorous growths are due to initiation or due to promotion by the suture remains unknown. A 3-O silk suture was therefore placed in the bladders of rats for 4 or 8 weeks. After removal of the suture and a period of recovery, the bladders of these and sham-operated control rats were exposed to N-methyl-N-nitrosourea (MNU) in order to examine whether the effects of the suture were reversible following its removal from the bladder. In addition, the bladder mucosa was exposed to either MNU or Ringer's solution followed by placement of the silk suture in the bladder wall in order to examine promotor activity of the suture. The tumor incidence induced by MNU was little influenced by the prior temporary placement of the suture in the bladder wall, thus indicating a reversibility of the effects of the suture. The placement of the silk suture in the bladder wall that had a prior exposure to MNU resulted in a significant incidence of invasive tumors. All these results are consistent with the fact that a silk suture in the bladder acts as a promoter but not as an initiator.
Exp Mol Pathol 1987 Oct
PMID:Growth promotion by silk sutures in the urinary bladder of rat. 365 51

The dependence of electrogenic sodium pump activity on changes in the cell volume of Helix pomatia neurons with different levels of intracellular sodium ion concentration was studied. Hypertonic solutions caused hyperpolarization of the membrane and increased membrane resistance in cells with a low sodium content (low-sodium cells; LSC). The activity of the electrogenic sodium pump in hypertonic solutions was increased compared to the activity in hypotonic solutions in LSC and decreased in cells with a high sodium content (high-sodium cells; HSC). The concentration of ouabain which led to maximal inhibition of active 22Na efflux from the neurons was 10(-4) M. Lower concentrations of ouabain (10(-8) M and lower) did not inhibit the sodium pump but stimulated it. The swelling of neurons in hypotonic solutions was accompanied by an increase in the number of binding sites for ouabain, while shrinking in hypertonic solutions led to the opposite effect--a decrease in binding sites. An increase in the number of binding sites also took place in normal isotonic potassium-free solutions compared with normal Ringer's solution. Two saturable components of ouabain binding were detectable in all solutions examined. gamma-Aminobutyric acid (GABA) and acetylcholine (ACh) increased the number of ouabain binding sites on the membrane. The results suggest that there are two opposite mechanisms by which cell volume changes can modulate the pump activity. One of them depends on the intracellular sodium ion concentration and causes pump activation in hypertonic solutions in LSC and saturation in HSC, while a second mechanism mediates the activating effect of cell swelling on the sodium pump in HSC. In addition, there may be a negative feedback between the pump activity and the number of functioning pump units in the membrane.
Cell Mol Neurobiol 1984 Dec
PMID:Autoregulation of the electrogenic sodium pump. 624 43

Several different toxins having specific effects on the kinetics of sodium channels have been isolated from the venoms of two scorpions. A combination of two steps of ion-exchange chromatography has been used to purify these toxins, whose sizes and purities have been assayed by gel filtration, urea/sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and isoelectric focusing. The actions of the toxins and their relative potencies have been determined by studying the modifications they produce in action potential shape, using the sucrose-gap method, and in ionic current kinetics, measured under voltage-clamp, both assays performed on myelinated axons of frogs and toads. The venom of Leiurus quinquestriatus scorpions yielded two active neurotoxins; the major neurotoxin has a mass of approximately 7000 daltons. This major toxin affected the sodium channel inactivation process exclusively, slowing the rates of inactivation as well as preventing complete inactivation from occurring in some of the channels. Such slowed and incomplete sodium inactivation resulted in action potentials that were prolonged, from their usual duration of 5-8 msec to hundreds of milliseconds or even seconds. Five toxins were isolated from the venom of Centruroides sculpturatus Ewing scorpions, all of which also had masses of approximately 7000-7500 daltons. Four of these toxins acted primarily on the activation process of sodium channels, producing a novel increase in sodium permeability upon repolarization of the nerve membrane following a depolarizing pulse, as previously described for the crude venom [Cahalan, M. D. J. Physiol. (Lond.) 244:511-534 (1975)]. These toxins also caused repetitive firing of action potentials in single axons in response to one stimulating pulse, as well as spontaneous impulse firing. A fifth neurotoxin from C. sculpturatus venom had effects similar to those of the L. quinquestriatus toxins, slowing and preventing complete sodium inactivation. The effect of this toxin was slowly removed during external perfusion by Ringer's solution.
Mol Pharmacol 1983 Mar
PMID:Purification and physiological characterization of neurotoxins from venoms of the scorpions centruroides sculpturatus and leiurus quinquestriatus. 630 Jun 54

1. The aim of this study was to elucidate if the K+ uptake was higher in cultured human glioma cells than in cells from other malignant tumors and to analyze the importance of membrane potential and K+ channels for the uptake. 2. K+ transport properties were studied with the isotopes 42K and the K-analogue 201Tl. 3. Comparison with cultured cells from other malignant tumors showed that the specific steady-state accumulation of Tl+ was significantly higher in glioma cells (U-251MG and Tp-378MG). 4. In Ringer's solution at 37 degrees C the rates of K+ and Tl+ uptake were both inhibited by about 55% in ouabain and 60% in furosemide, bumetanide, or Na(+)- or Cl(-)-free medium. This indicated that the routes for K+ and Tl+ uptake were similar and due to Na,K-ATPase-dependent transport and to Na-K-Cl cotransport. 5. About 10% of the uptake was neither ouabain nor bumetanide sensitive. Ba2+, which is known to block inward-rectifying K+ channels and to depolarize glial cells, and other K+ channel blockers (Cs+ and bupivacaine), had no effect on Tl+ uptake. 6. Metabolic inhibition with dinitrophenol reduced the uptake rate to 17%. 7. The washout of Tl+ was unaffected by bumetanide and K+ channel blockers, but dinitrophenol caused a transient increase of 75%, an effect which persisted in the presence of K+ channel blockers. 8. It was concluded that the high specific K+ and Tl+ accumulation in cultured human glioma cells was due not to the presence of inwardly rectifying K+ channels or other identified K+ channels, but to Na,K-ATPase dependent transport and Na-K-Cl cotransport.
Cell Mol Neurobiol 1995 Jun
PMID:Mechanism of high K+ and Tl+ uptake in cultured human glioma cells. 755 34

We have investigated the effect of both adenosine triphosphate (ATP) and uridine triphosphate (UTP) on the fluid transport, transepithelial electric potential difference (PD), and unidirectional chloride flux when applied apically to cultured human surface respiratory epithelial (HSRE) cells in a double-compartment chamber. The effects of ATP and UTP (both 100 microM) were examined in cells either untreated or pretreated with 100 microM amiloride in lactated Ringer's solution. ATP or UTP was added to the apical solution in a 100 microliters final volume. After a 2-h incubation period, the change in fluid transport was measured by weighing the apical fluid. Compared with control, amiloride blocked the fluid absorption by HSRE cells. The addition of ATP or UTP, either alone or after pretreatment with amiloride, induced a similar and significant increase in the apical fluid and chloride flux (P < 0.001 and P < 0.005, respectively). The changes in both fluid transport and chloride flux were accompanied by changes in PD. A blocker for chloride transport, 4,4'-diisothiocyano-2,2'-stilbene disulfonate, at 500 microM significantly blocked the ATP-stimulated fluid transport (P < 0.05) and chloride flux (P < 0.01). These results support the hypothesis that extracellular ATP and UTP increase the fluid transport by respiratory epithelial cells and may be useful in the hydration of mucus and respiratory mucosa.
Am J Respir Cell Mol Biol 1994 Apr
PMID:Effect of extracellular ATP and UTP on fluid transport by human nasal epithelial cells in culture. 813 52

The distribution of gamma-aminobutyric acid (GABA) receptor subunits such as GABAAR-gamma 1 and GABAAR-gamma 2, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type receptor subunits such as GluR-1, GluR-2/3 and GluR-4, and N-methyl-D-aspartic acid (NMDA) type subunits such as NR1 were investigated by immunocytochemistry. Furthermore, the roles of these amino acids, GABA and glutamate, on salivation were analyzed in the rat submandibular and sublingual glands. Some similarities were observed in the distribution patterns of GABAA type receptors and AMPA receptors. In the submandibular ganglion cells, collecting ducts and striated ducts, these subunits were expressed strongly; however, there were some differences in their expression patterns between the submandibular and sublingual gland acinar cells. Since these receptor subunits were expressed in the acinar cell bodies of the submandibular gland, they were not expressed in the acinar cells but were expressed in the myoepithelial cells in the sublingual gland. On the other hand, no NR1 expression was observed. To examine the roles of GABA and glutamate in salivation, the submandibular and sublingual glands were perfused partially with Ringer's solution via a facial artery to avoid systemic influence, and substrates were infused into the perfusion solution. No salivary secretion was evoked by GABA or glutamate infusion in the absence of electrical stimulation (2-3 V, 5 ms, 20 Hz). Salivary flow evoked by electrical stimulation of the chorda-lingual nerve caused significant inhibition by GABA (10(-6), 10(-5), 10(-4) and 10(-3) M) and the GABAAR agonist muscimol 10(-3) and 10(-6) M) (n = 6, P < 0.05). Such GABA-induced inhibition was antagonized by the GABAAR antagonists bicuculline (BCC; 10(-6) and 10(-3) M) and picrotoxin (PTX; 10(-6) and 10(-3) M). On the other hand, salivary flow evoked by electrical stimulation (8-10 V, 5 ms, 20 Hz) of the superior cervical ganglion (SCG) was not affected by GABA. While high doses of glutamate (10(-1) M) and NMDA (10(-1) M) showed no effects on salivary flow despite application of electrical stimulation, AMPA at a high concentration (10(-1) M) significantly inhibited salivary secretion (n = 6, P < 0.05). These studies revealed that inhibitory and excitatory amino acid receptors such as GABAA and AMPA type receptors are coexpressed in the rat salivary glands, and that GABA inhibits salivary secretion via GABAA receptors which may act with acetylcholine. However, the role of glutamate in salivation remains unclear despite the presence of AMPA type receptors. The present findings suggest that glutamate does not act alone but with other substances such as peptides and/or other amino acids.
Brain Res Mol Brain Res 1995 Nov
PMID:Role of amino acids in salivation and the localization of their receptors in the rat salivary gland. 875 Aug 85

The purpose of this work was to study the effects of ultraviolet (UV) irradiation on denucleation of eggs and investigate the heat-shock conditions for diploidization for induction of androgenesis in muskellunge, Esox masquinongy. Several egg incubation media, including saline, Ringer's solution, and Ringer's solution supplemented with bovine serum albumin (BSA), were found suitable to maintain the egg fertility as high as in muskellunge ovarian fluid. The optimal doses of UV radiation were 660-1320 J/m2, at which 100% haploid larvae were produced at a hatching rate of 22.5 +/- 2.8%. UV irradiation at low doses (165-330 J/m2) generated abnormal larvae, which were morphologically identical to haploids. Using a flow cytometry method, it was found that cellular DNA content of these larvae was close to that of diploids but significantly lower in value and had a wider distribution (expressed as coefficient of variation) than that of control fish. This suggested that a low dose of UV irradiation might cause gene mutations, alteration of chromosomal conformation and fragmentation, but did not prevent maternal DNA from participating in mitotic division. Interference of maternal DNA residues could be another reason for the poor viability of androgenetic fish. A high dose of UV radiation (1980 J/m2) caused development of severely deformed embryos, indicating that UV radiation also damaged molecules in the eggs other than the denucleation. Our results suggest that classic color and allozyme markers might not be sufficient to prove a complete androgenesis. In order to optimize time and duration of shock for induced diploidization, we investigated the heat-shock conditions for inhibiting the first mitotic cleavage through induction of homozygous gynogenesis. We found that heat-shock treatment at 31 degrees C for 9 min starting at 1.4 tau 0 (a dimensionless factor describing progress in embryo development) after fertilization produced the highest percentage of diploids at hatching.
Mol Reprod Dev 1998 Jan
PMID:Androgenesis and homozygous gynogenesis in muskellunge (Esox masquinongy): evaluation using flow cytometry. 940 91

To develop a model for the mechanisms of organic acid excretion in nematodes, we measured the concentrations of volatile fatty acids (VFAs), pH and electrical potentials across hypodermal and muscle membranes and across the composite body wall (consisting of hypodermis, muscle and cuticle) of Ascaris suum using standard chromatographic and microelectrode recording techniques. In incubates containing one parasite in 20 ml modified Ascaris Ringer's solution, the level of combined VFAs excreted into the medium increased linearly for about 18 h, then plateaued at a concentration of 4.2 mM; the medium acidified rapidly to a plateau at about pH 5.0 within 4-6 h. Following 24 h incubations, the concentrations of VFAs in the hypodermis, muscle, and pseudocoelomic compartments were 62.4 +/- 8.1, 62.3 +/- 7.8 and 74.4 +/- 3.2 mM, respectively. The pseudocoelomic fluid was more acidic (pH 6.52 +/- 0.06) than the hypodermis (pH 6.78 +/- 0.03) or muscle (pH 6.77 +/- 0.03). These data and the electrical potentials across hypodermal (-57.9 +/- 6.3 mV) and muscle (-30.3 +/- 0.8 mV) membranes were used to determine the equilibrium concentrations for protonated (HVFA) and anionic (VFA-) forms of the acids across these membranes and across the cuticle. Under these conditions, little transmembrane or transmural excretion of HVFAs is expected to occur in A. suum. However, a 16-27 mV driving force for VFA- excretion exists across hypodermal and muscle membranes, and a larger driving force is predicted to exist for these anions across the cuticle. This driving force could provide potential energy for VFA- excretion through anion channels which exist in muscle and hypodermal membranes of this parasite, or for facilitated transport systems.
Mol Biochem Parasitol 1998 Jun 01
PMID:Biophysical model for organic acid excretion in Ascaris suum. 966 3


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