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EFFECT OF CYANIDE AND ELECTRICAL STIMULATION ON PHOSPHOINOSITIDE METABOLISM IN LOBSTER NERVES 总被引:5,自引:2,他引:3
Anita C. Birnberger K. L. Birnberger S. G. Eliasson P. C. Simpson 《Journal of neurochemistry》1971,18(7):1291-1298
The contents of phosphoinositides, ATP, glucose and lactate in leg and claw nerves of the lobster were determined. Nerves were also analysed after cyanide poisoning, after electrical stimulation, and 1 h after removing the leg from the lobster. Cyanide poisoning decreased the levels of ATP and glucose and increased the content of lactate but did not alter the levels of phosphoinositides. Nerves left in situ for 1 h after disconnection from the central nervous system exhibited a decrease in the content of tri-phosphoinositides (TPI) of 50 per cent, without changes in ATP, glucose or lactate. The TPI change was reversed after incubation for 1 h in oxygenated seawater. Nerves labelled in vivo with 32P were removed and stimulated at 50 Hz for 5 min. The turnover of TPI phosphorus increased on stimulation in both normal and cyanide-poisoned nerves. In contrast, turnover of ATP increased after stimulation in normal nerves but not in cyanide-treated nerves. We sought to determine whether polyphosphoinositides play a greater role in resting metabolism of the nerve or in the conducting mechanisms. Our results make more likely the involvement of TPI in permeability changes of neural membranes during excitation. 相似文献
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THE BINDING OF BOTULINUM TOXIN TO MEMBRANE LIPIDS: SPHINGOLIPIDS, STEROIDS AND FATTY ACIDS 总被引:10,自引:3,他引:7
A number of lipids known to be constituents of nerve-ending membranes were tested for their ability to inactivate botulinum toxin. Inactivation of the toxin by a lipid was taken as presumptive evidence that the lipid might be the in vivo receptor for the toxin. Several sphingolipids (sphingosine, galactosylceramide, glucosylceramide, lactosylceramide, cytolipin K and cytolipin R), steroids (cholesterol and deoxycholic acid) and fatty acids (palmitic acid, stearic acid, prostaglandin E1) did not affect the potency of botulinum toxin, and thus were discounted as potential toxin receptors. However, the gangliosides did inactivate botulinum toxin rapidly (in less than 5 min), within a temperature range of 2°-40°C, and at ionic strengths of 0.05-0.40. Inactivation diminished as pH fell below 6. The activity of gangliosides in suppressing the potency of botulinum toxin was a function of the number of sialic acid residues in the lipid. Thus, the data suggest that a molecule containing sialic acid may be the receptor for the toxin. 相似文献
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Dr. J. Simpson 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1964,48(3):277-282
Summary Queens breathed continuously while they were piping, and were able to pipe with all spiracles except one blocked, so the sound could not have been produced by air entering or leaving the spiracles. It is produced by operating the flight motor without spreading the wings, and is radiated partly by the substratum, to which the vibrations are communicated by pressing the thorax against it.
Piping in English includes both tüten and quaken in German. Both sounds are produced in the same way but quaken is heard when the queen is in her cell (Armbruster, 1922). 相似文献
Zusammenfassung Königinnen atmeten während des Tütens ununterbrochen, und waren zum Tüten fähig, wenn alle Atemlöcher bis auf eines blockiert waren, so daß der Laut nicht durch Ein oder Austreten der Luft durch die Atemlöcher hervorgerufen sein konnte. Er wird erzeugt, indem der flight motor ohne das Ausbreiten der Flügel funktioniert, und teilweise durch das Substrat verbreitet, auf das die Schwingungen durch Anpressen des Thorax übertragen werden.
Piping in English includes both tüten and quaken in German. Both sounds are produced in the same way but quaken is heard when the queen is in her cell (Armbruster, 1922). 相似文献
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To demonstrate skeletal metastases before radiographic changes were apparent, Sr85 scans were carried out on 46 patients who complained of sketetal pain but whose radiographs were negative. Positive scans were obtained in 34 patients, 20 of whom were subsequently shown to have metastases; three did not have skeletal metastases a year or more later; the outcome is unknown in 11 patients. Twelve patients had negative scans: three ultimately developed metastases, six did not, and three were inconclusive. Autoradiographs demonstrated Sr85 concentrations in areas of reactive osteogenesis.Although not specific for skeletal metastases, Sr85 scans are most helpful in substantiating this diagnosis when radiographic changes are absent. 相似文献
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