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- Gogan, P., et al.
(author)
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On re‐excitation of feline motoneurones: its mechanism and consequences.
- 1984
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In: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 350, s. 81-91
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Journal article (peer-reviewed)abstract
- Conditions required for re‐excitation of lumbosacral motoneurones, i.e. for double impulses in the motor axons associated with a single soma‐dendritic action potential, were examined in cats anaesthetized with pentobarbitone and paralysed with gallamine triethiodide. Simultaneous recording from a motoneurone (intracellular, and in some experiments also extracellular), and from its axon in a ventral root, was used to assess the relations between the soma and the double axonal action potentials. Action potentials (greater than 70 mV) evoked by brief depolarizing current pulses applied intracellularly were never observed to cause re‐excitation. Re‐excitation could, however, be regularly induced by procedures which increased the delay between the initial segment and soma‐dendritic components of these potentials. Re‐excitation could be evoked (i) when brief hyperpolarizing pulses were applied before the onset of the soma‐dendritic spikes, (ii) when the depolarizing pulses were applied on a background of long hyperpolarizing pulses or (iii) when two action potentials were evoked in a quick succession (by two brief depolarizing pulses). No relationship was found between the presence of re‐excitation of motor axons and the presence of the delayed depolarization which follows the soma‐dendritic spikes. Neither re‐excitation nor delayed depolarization were found to be dependent upon re‐excitation of the initial segment. These observations are thus at variance with previous suggestions that the initial segment spikes induce the re‐excitation of motor axons and that the initial segment spikes cause the delayed depolarization following soma‐dendritic spikes. Since re‐excitation of a motor axon occurred without any signs of a second initial segment spike, it is concluded that it is initiated at the level of the axon, most likely at the first node of Ranvier. Re‐excitation of motor axons was also observed during repetitive firing induced by intracellular current injection. However, it occurred then only occasionally, and only under strong depolarizing drive. It is thus not expected to be a common phenomenon under natural conditions of repetitive firing. © 1984 The Physiological Society
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- Gustafsson, A, et al.
(author)
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Rapid induction of seven proteins in human lymphocytes by interferon; correlation to natural killer cell activity.
- 1982
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In: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 129:5, s. 1952-9
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Journal article (peer-reviewed)abstract
- The early effects of interferon (IFN) on the synthesis of protein in human nylon wool-nonadherent lymphocytes have been stimulated by use of two-dimensional electrophoresis. IFN-alpha or -beta as well as Escherichia coli-produced IFN-alpha 2 induced the rapid formation of seven proteins (Mr 80, 75, 62, 53, 38, 36, and 33 kD). At least five proteins were expressed within 2 hr of incubation with IFN. The synthesis of the seven proteins seemed to require rapid transcription of new RNA, because actinomycin D markedly inhibited their formation only when added less than 30 min after IFN. A good correlation was found between the ability of actinomycin D to inhibit both the formation of new proteins and the augmentation of natural killer (NK) cell activity. Screening of a panel of 10 hematopoietic and two anchorage-dependent cell lines revealed that p62 and p38 were induced in most cell lines, whereas p80 and p33 were preferentially induced in lymphoid cell lines. Three proteins could not be induced by IFN in any of the 12 cell lines, and thus could represent molecules mediating differentiated functions, possibly involved in NK cell function.
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