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Electrolyte profile of Malaysian mothers' milk.
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First case of illegal euthanasia in Spain: fatal oral potassium cyanide poisoning.
A fatal case of intentional oral cyanide poisoning in a tetraplegic patient whose repeated legal requests to be allowed to perform euthanasia had been refused, is reported. The postmortem provided no specific findings and the diagnosis was based on the toxicological analysis of the different samples available. Cyanide was determined in all biological (blood, vitreous humour, bile, urine and viscera) and non-biological samples_received (liquid found in a glass beside the body in the scene of the crime). The high cyanide concentrations in blood (21.5 mg/L) are consistent with death through cyanide poisoning. Also, the cyanide concentration in the water held in the glass from which the casualty presumably drank 81900 mg/L), and the high levels of potassium ion found (186 mEq/L), allowed us to conclude that the death was due to the intake of an amount of potassium cyanide between 500 and 1000 mg.
The role of oral electrolytes in the management of acute gastroenteritis in non-hospitalised children.
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Oral (or nasogastric) maintenance therapy for cholera patients in all age-groups.
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[Change in the acid-base state and electrolyte metabolism in inflammatory diseases of the internal genitalia in the subacute stage occurring after abortion under the influence of mud therapy].
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Gossypol related hypokalemia. Clinicopharmacologic studies.
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Frequency and significance of potassium disturbances in sick children.
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Oral rehydration therapy.
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Freezability of bovine spermatozoa in Tris-buffered yolk extenders containing different levels of Tris, sodium, potassium and calcium ions.
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Proceedings: Epinephrine-induced pulmonary edema in rabbits and changes in the levels of lung lipids and plasma potassium ion. II.
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Potassium channel kinetics in squid axons with elevated levels of external potassium concentration.
Potassium ion current in squid axons is usually modified by the effects of ion accumulation in the periaxonal space during voltage-clamp depolarization. The time course of potassium channel activation and ion accumulation usually overlap. A widely accepted procedure for circumventing the effects of accumulation in measurements of activation kinetics consists of measuring the difference in the current at the end of a depolarizing pulse and immediately following return of the membrane potential to the holding level. This instantaneous jump procedure is based upon the assumptions that the potassium channel current-voltage relation (IV) is a linear function of the driving force, and that the IV and the potassium channel-gating kinetics are both independent of ion accumulation. The latter assumption appears to be appropriate for activation kinetics. However, both assumptions concerning the IV are incorrect, in general. Consequently, the jump procedure provides a misleading view of gating kinetics for membrane depolarizations that produce net current flow. Jump conductance measurements for depolarizations that produce little or no net current indicate that the Hodgkin-Huxley n4 model of potassium channel kinetics is appropriate for the physiological range of membrane potentials.
Scintillation-based potassium signalling using 2,5-diphenyloxazole-tagged aza-18-crown-6.
In the presence of ionising radiation, an aza-18-crown-6 molecule covalently attached to a 2,5-diphenyloxazole (PPO) moiety scintillates weakly, addition of potassium ions results in enhanced levels of scintillation, the degree of scintillation reflecting the concentration of the potassium ions.
Solutes contributing to osmotic adjustment in cultured plant cells adapted to water stress.
Osmotic adjustment was studied in cultured cells of tomato (Lycopersicon esculentum Mill cv VFNT-Cherry) adapted to different levels of external water potential ranging from -4 bar to -28 bar. The intracellular concentrations of reducing sugars, total free amino acids, proline, malate, citrate, quaternary ammonium compounds, K(+), NO(3) (-), Na(+), and Cl(-) increased with decreasing external water potential. At any given level of adaptation, the maximum contribution to osmotic potential was from reducing sugars followed by potassium ions. The sucrose levels in the cells were 3- to 8-fold lower than reducing sugar levels and did not increase beyond those observed in cells adapted to -16 bar water potential. Concentrations of total free amino acids were 4- to 5-fold higher in adapted cells. Soluble protein levels declined in the adapted cell lines, but the total reduced nitrogen was not significantly different after adaptation. Uptake of nitrogen (as NH(4) (+) or NO(3) (-)) from the media was similar for adapted and unadapted cells. Although the level of quaternary ammonium compounds was higher in the nonadapted cells than that of free proline, free proline increased as much as 500-fold compared to only a 2- to 3-fold increase observed for quaternary ammonium compounds. Although osmotic adjustment after adaptation was substantial (up to -36 bar), fresh weight (volume increase) was restricted by as much as 50% in the adapted cells. Altered metabolite partitioning was evidenced by an increase in the soluble sugars and soluble nitrogen in adapted cells which occurred at the expense of incorporation of sugar into cell walls and nitrogen into protein. Data indicate that the relative importance of a given solute to osmotic adjustment may change depending on the level of adaptation.
Responses of the "hypoxic resistant" R15 neuron of Aplysia to reduced extracellular oxygen tensions.
These results may be interpreted as follows: Calcium entry into R15 is brought about by hypoxia. The amount of intracellular calcium is probably buffered by the endoplasmic reticulum and the mitochondria whose processes of oxidative phosphorylation exchange protons for Ca2 + ions. (12, 13, 14) It is known that calcium entry into molluscan neurons inactivates the Ca2 + current and that potassium conductance is increased by higher levels of intracellular Ca2 +. (8, 9, 10, 26) Therefore, inactivation of the calcium channel through entry explains why the spike amplitude is depressed without affecting the threshold for activation as shown in Table 1. Secondly, an increased potassium conductance resulting from an increase in intracellular Ca2 + accounts for the membrane hyperpolarization. Little effect, then, is seen on the level of intracellular potassium ion activity (aiK +) since the membrane potential becomes more permeable to potassium and hyperpolarizes. Therefore, the value of EK is relatively unchanged during hypoxia; yet the values of the membrane potential (Em) hyperpolarize corresponding to an increase in potassium conductance. In summary, not only is the cyclical bursting pattern of R15 altered by reduced oxygen tensions in the suffusate but also each spike is depressed in amplitude because of an overabundant calcium entry during hypoxia. Presumably, the additional minute amounts of calcium are buffered by uptake into the mitochondria and endoplasmic reticulum, but there may be a significant increase in intracellular calcium enough so that the pump is not sufficient to move calcium externally without the energy resulting from the driving force of the sodium equilibrium potential (ENa).(ABSTRACT TRUNCATED AT 250 WORDS)
Calcium ion levels in resting and depolarized goldfish retinal ganglion cell somata and growth cones.
1. We have estimated free, intracellular calcium ion concentrations ([Ca]i) in isolated retinal ganglion cells of adult goldfish by ratio-imaging fura-2 emission intensity at two excitation wavelengths. Here we describe [Ca]i in these cells, both at rest and during depolarization by elevated levels of extracellular potassium ions ([K]o). 2. [K]o was varied between 5 and 60 mM in sodium-free, tetrodotoxin-containing salines. Ganglion cell membrane potential, measured with patch electrodes, fell with each increment of [K]o used, from approximately -70 mV in 5 mM K+ to approximately -20 mV in 60 mM K+. 3. In control saline, [Ca]i was roughly 120 nM in cell somata and at least twofold higher in their growth cones. [Ca]i increased in both somata and growth cones to as high as 1.5 microM in salines containing 60 mM K+. [Ca]i exceeded 1.5 microM in some cells in high-K+ salines, although these levels could not be quantified accurately with fura-2. 4. Increases in [Ca]i elicited by elevated [K]o persisted for the duration of the exposure to high-K+ saline and were blocked by replacement of most of the bath Ca2+ by Co2+. These increases in [Ca]i were also sensitive to dihydropyridine calcium-channel ligands, viz., enhanced by BAY K 8644 (3 microM) and antagonized by nifedipine (10 microM). 5. Partial recovery of control [Ca]i occurred when [K]o was reduced to 5 mM after exposure to high-K+ saline and in high-K+ saline when nifedipine was included. These results show that goldfish retinal ganglion cells can partially buffer intracellular Ca2+ in the absence of extracellular Na+ ions. 6. These results provide measurements of the changes in [Ca]i brought about by depolarization of goldfish retinal ganglion cells in Na(+)-free salines. In these salines, at least part of the increase in [Ca]i appears to result from Ca2+ influx through a voltage-activated, noninactivating calcium conductance in the somata and growth cones of these cells. These measurements complement whole-cell patch-clamp and vibrating microprobe recordings from the somata and neurites of these cells and also immunocytochemical studies and patch-clamp measurements in amphibian, reptilian, and mammalian retinal ganglion cells.
Characterization studies on the membrane-bound adenosine triphosphatase (ATPase) of Azotobacter vinelandii.
The adenosinetriphosphatase (ATPase) (EC 3.6.1.3) activity in Azotobacter vinelandii concentrates in the membranous R3 fraction that is directly associated with Azotobacter electron transport function. Sonically disrupted Azotobacter cells were examined for distribution of ATPase activity and the highest specific activity (and activity units) was consistently found in the particulate R3 membranous fraction which sediments on ultracentrifugation at 144 000 X g for 2 h. When the sonication time interval was increased, the membrane-bound ATPase activity could neither be solubilized nor released into the supernatant fraction. Optimal ATPase activty occurred at pH 8.0; Mg2+ ion when added to the assay was stimulatory. Maximal activity always occurred when the Mg2+:ATP stoichiometry was 1:1 on a molar ratio at the 5 mM concentration level. Sodium and potassium ions had no stimulatory effect. The reaction kinetics were linear for the time intervals studied (0-60 min). The membrane-bound ATPase in the R3 fraction was stimulated 12-fold by treatment wiTH TRypsin, and fractionation studies showed that trypsin treatment did not solubilize ATPase activity off the membranous R3 electron transport fraction. The ATPase was not cold labile and the temperature during the preparation of the R3 fraction had no effect on activity; overnight refrigeration at 4 degrees C, however, resulted in a 25% loss of activity as compared with a 14% loss when the R3 fraction was stored overnight at 25 degrees C. A marked inactivation (although variable, usually about 60%) did occur by overnight freezing (-20 degrees C), and subsequent sonication failed to restore ATPase activity. This indicates that membrane reaggregation (by freezing) was not responsible for ATPase inactivation. The addition of azide, ouabain, 2,4-dinitrophenol, or oligomycin to the assay system resulted in neither inhibition nor stimulation of the ATPase activity. The property of trypsin activation and that ATPase activity is highest in the R3 electron transport fraction suggests that its probable functional role is in coupling of electron transport to oxidative phosphorylation.