Thermal conductivity of deformed potassium chloride.
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K(+) and Cl(-) contents of guard cells and of ordinary epidermal cells were determined in epidermal samples of Allium cepa L. by electron probe microanalysis; malate contents of the same samples were determined by enzymic oxidation. KCl was, in general, the major osmoticum in guard cells, irrespective of whether stomata had opened on leaves or in epidermal strips floating on solutions. The solute requirement varied between 50 and 110 femtomoles KCl per micrometer increase in aperture per pair of guard cells. Stomata did not open on solutions of K iminodiacetate, presumably because its anion could not be taken up. Stomata opened if KCl or KBr was provided. Taken together, the results indicate that the absence of starch from guard cells deprived them of the ability to produce malate in amounts of osmotic consequence and that the presence of absorbable Cl(-) (or Br(-)) was necessary for stomatal opening.Previous nutrient supply of the plants determined whether the charges of K(+) in guard cells were completely balanced by Cl(-) or only partially. Addition of K(2)SO(4) to the nutrient solution reduced the participation of Cl(-) in stomatal ion transfer, even if epidermal strips of these plants were later exposed to KCl solution. The anion supplying the charge complement in these cases is not known.Although malate appeared not to participate in stomatal ion transfer in onion, epidermal samples of this species did contain malate. Malate accumulated in the epidermis of leaves put into the light but disappeared from illuminated epidermal strips floating on solutions. In whole leaves, epidermal malate content was positively correlated with stomatal opening; in epidermal strips floating on solutions, the correlation was negative or absent.
Tissue ATP concentrations in slices of red beet increase progressively with time for up to 7 days after cutting the root. ATP levels are higher in slices taken from stored roots than in slices from fresh roots. ATP is reduced during incubation in salt solutions.Plasmalemma influxes were measured by 6 minutes incubation with (42)K and/or (36)C1 under conditions in which cation and anion influxes are independent. Both fluxes showed an approximately linear correlation with ATP level when the latter was varied by addition of CN(-), carbonyl cyanide m-chlorophenylhydrazone, or oligomycin, except for Cl influx with oligomycin, where oligomycin had a greater effect on Cl influx than could be accounted for by the reduction in ATP alone.These results support the view that K(+) and Cl(-) influxes are both energized directly or indirectly by ATP, and in addition that the Cl pump may be directly inhibited by oligomycin.
Vacuoles were isolated via protoplasts from the leaves of a halophyte Atriplex gmelini C.A.Mey., grown in culture solution supplemented with 250 millimolar NaCl. Lysis of the protoplasts was induced by lowering the medium osmolarity (1.2 to 1.0 molar sorbitol) and adding a detergent, a synthesized cholate derivative, 3-([3-cholamidopropyl] dimethylammonio)-1-propanesulfonate at a concentration of 0.5 millimolar and the resulting vacuoles were purified by successive dilution and floatation. Isolated vacuoles contained almost the same concentration of sodium (569 millimolar) and chloride (260 millimolar) as recorded in protoplasts (582 and 254 millimolar, respectively), suggesting that the vacuoles are the major sequestration site of NaCl in leaves of halophytes. Betaine concentration in the protoplasts was about 16 millimolar, while that in vacuoles was only about 0.24 millimolar, indicating that betaine is accumulated in the cytoplasm as a compatible solute.
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In mature central neurons, chloride extrusion mediated by the K-Cl cotransporter KCC2 appears to be largely responsible for the Cl(-) driving force that allows gamma-aminobutyric acid(A) (GABA(A)) receptor activation to trigger a hyperpolarization. In its absence, GABA's effect is typically depolarizing and often excitatory. We examined the colocalization of KCC2 and GnRH in adult male and female mice using a combined in situ hybridization-immunofluorescence procedure. We found that KCC2 was localized to approximately 34% of GnRH neurons. This proportion was similar in females and males. However, females exhibited a marked rostrocaudal gradient of colocalization that was not seen in males. By contrast, KCC2 was localized to nearly all vasopressin neurons of the supraoptic nucleus. These results indicate that a substantial fraction of GnRH neurons may be depolarized and excited by GABA(A) receptor activation throughout life, supporting the existence of functionally heterogeneous subpopulations.
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We have discovered that the gerbil's chorda tympani nerve response to sucrose is suppressed by p-nitrophenyl alpha-D-glucopyranoside (PNP-Glu) and chloramphenicol (CAP). Mixture experiments of PNP-Glu and CAP with sodium chloride, potassium chloride, hydrochloric acid, and sucrose gave rise to the following observations: Neither PNP-Glu nor CAP alone stimulates the gerbil's taste nerve; while the sucrose response is suppressed by these inhibitors, taste responses produced by sodium chloride, potassium chloride, and hydrochloric acid are unaffected by the presence of PNP-Glu or CAP; the antagonisms of PNP-Glu and CAP were surmounted by a high concentration of sucrose; CAP is a more potent antagonist (IC50 = 0.0013 M) than PNP-Glu (IC50 = 0.022 M), and both are more potent than methyl 4,6-dichloro-4,6-dideoxy-alpha-D-galactopyranoside (IC50 = 0.048 M); and sucrose antagonism occurs only when PNP-Glu and CAP are mixed with sucrose. It is short-lived and ceases when the mixtures are rinsed from the gerbil's tongue. Structure-activity studies provided the following information: The alpha anomer of PNP-Glu is a more potent inhibitor than its beta anomer; among the PNP-Glu derivatives tested (p-aminophenyl, p-nitrophenyl, and phenyl) only p-nitrophenyl inhibited; among the nitrophenyl galactosides, the para derivative was more potent than the ortho or meta; and p-nitrophenyl alpha-D-mannopyranoside and p-nitrophenyl alpha-D-galactoside are slightly more potent than PNP-Glu. On the basis of concentration experiments, we believe that the inhibitory mechanisms of PNP-Glu and CAP are different, which suggests the existence of at least 2 sucrose receptor sites.
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One hundred and seventy-four rats received a standardized 0.4-ml injection into the left infraorbital nerve and all solutions contained lignocaine 0.25 g dl-1. In groups 1-4, the solutions were isoosmotic and contained, besides sodium chloride, potassium chloride 0 or 4 mmol litre-1 and glucose 0 or 20 mmol litre-1 (0 or 360 g dl-1). For groups 5-8, the solutions were hypoosmotic, containing sodium chloride to 0.6 of normal tonicity but were otherwise identical to solutions 1-4. Presence and duration of sensory block were determined from the reflex sublingual electromyographic response to periodic homolateral and contralateral electrical stimulation of the upper lip. In groups 1-4, the presence of potassium chloride 4 mmol litre-1 approximately doubled the duration of blockade (P less than 0.001). Groups 5-8 showed that hypoosmolarity also doubled the duration of block (P less than 0.001), but hypoosmolarity and potassium chloride did not have additive effects. It is concluded that addition of potassium- chloride 4 mmol litre-1 to isotonic solutions of lignocaine is likely to enhance their clinical effectiveness.
To examine the effect of chloride-containing potassium supplements on chloride titrator estimates of dietary sodium intake, we gave normal subjects diet containing 10, 100, or 200 mEq/d sodium in random order either as such, or supplemented with one of two potassium supplements. One regimen consisted of potassium 45 mEq/d with 12 mEq/d chloride and 33 mEq/d of citrate and gluconate; the other contained 48 mEq/d potassium and 48mEq/d chloride. Increased potassium intake with either supplemented regimen resulted in increased 24-hour potassium excretion, which was manifested in only the diurnal collections. Increased chloride intake resulted in increased urinary chloride excretion both during the day and at night. At all chloride intakes, urinary sodium and chloride excretion were highly correlated. The 48 mEq/d chloride intake generated a relationship with the same slope but with a different intercept from the other two regimens. The highest chloride intake resulted in a greater chloride titrator reading; however, the relationship was sufficiently predictable that adjustments in interpretation could be easily made. We conclude that if daily potassium chloride intake is known, chloride titrators continue to be reliable tools for estimating dietary sodium intake.
Muscle from 47 individuals was analysed for water, sodium, chloride, potassium, and fat In 35 patients, samples were taken from three sites in one muscle, and in five from several muscles The average composition of different muscles differed, even in the same individual and the composition of samples varied considerably. Variability is the larger the more diverse the material. Coefficients of variation of muscle constituents are given for material from a biopsy, a muscle, a subject, or a given muscle in any subject. Some of these are large. Variability in the composition of samples is shown to be largely orderly. Water is closely correlated with tissue content of sodium plus potassium; sodium and chloride contents of samples show a positive correlation; potassium and sodium contents are strongly negatively correlated. Residual stochastic variability is small. Thus, when account is taken of the sodium content of a biopsy, the coefficient of variation for a potassium estimate falls from to about 6%. Some practical implications are deduced.
The toxicities of six chemicals (cadmium chloride, potassium dichromate, sodium dodecyl sulfate, potassium chloride, Tritox X-100 and copper (II) sulphate) was determined for three tropical freshwater cladoceran, Moinodaphnia macleayi, Ceriodaphnia rigaudii and Diaphanosoma brachyurum. The data was subsequently used to compare the relative sensitivity of the three species. Relative sensitivities were determined by comparing the 48-hour LC50 values using an independent t-test and interspecies correlation. Potassium dichromate was the most toxic compound tested, while potassium chloride was the least toxic to all three species. The 48 h LC50 values for D. brachyurum ranged from 0.003 mg/L to 30.4 mg/L; M. macleayi LC50 values ranged from 0.003 mg/L to 30.1 mg/L whereas for C. rigaudii the values ranging between 0.002 mg/L to 21.1 mg/L. The LC50 values for C. rigaudii was significantly less (P < 0.05) than M. macleayi for five of the compounds tested, whereas for D. brachyurum it was significantly (P < 0.05) less than four of the compounds tested. The interspecies correlation also suggested that C. rigaudii and M. macleayi were more similar in sensitivity (R2 = 0.96) to each other than D. brachyurum (R2 = 0.91 with M. macleayi, and R2 = 0.87 with C. rigaudii).
Human decidual explants were incubated in vitro in media containing 10(-5) mol/l ouabain or 10(-4) mol/l ouabain or 0.5 X 10(-4) mol/l bumetanide to change the intracellular ionic concentrations. In isosmotic incubations (osmolality 315 mmol/kg), no significant effect of either 10(-5) mol/l ouabain or 0.5 X 10(-4) mol/l bumetanide was found on the decidual prolactin secretion (D-PRL-s). 10(-4) mol/l ouabain significantly decreased both decidual prolactin production and D-PRL-s (P less than 0.05) and was therefore not used for the following cross-over experiments. Hyperosmotic media (387 mmol/kg) were produced by changing the concentration of either sodium chloride, potassium chloride, or mannitol. All increased D-PRL-s compared with the isosmotic media (315 mmol/kg). 10(-5) mol/l ouabain significantly diminished the increase otherwise elicited by the sodium chloride and the mannitol hyperosmotic media. However, in the hyperosmotic potassium chloride medium with 10(-5) mol/l ouabain, the D-PRL-s remained increased. The hyperosmotic medium (252 mmol/kg) reduced D-PRL-s compared with the isosmotic media (315 mmol/kg) and no significant effect of ouabain was found. Bumetanide did not change the D-PRL-s into any of the hypo- or hyperosmotic media compared with the secretion at 315 mmol/kg. Based on experience from other cell types, the results further indicate that the intracellular ionic concentrations could be of importance to the secretion of decidual prolactin in vitro.