| 1. |
- Lundberg, Peter, et al.
(författare)
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Permeabilization of Plant Cells: 31P NMR Studies of the Permeability of the Tonoplast
- 1986
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Ingår i: Plant Cell Reports. - : Springer. - 0721-7714 .- 1432-203X. ; 5, s. 13-16
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Tidskriftsartikel (refereegranskat)abstract
- A suspension culture of Catharanthus roseus has been used to study the permeability of cell membranes after treatment with various concentrations of a permeabilizing agent (DMSO). The uptake and release (after permeabilization) of inorganic phosphate (Pi) by cells have been investigated by 32P radiotracer and non-invasive phosphorus-31 NMR experiments. These studies have demonstrated that measurements of the Pi-efflux from plant cells provide a reliable measure of the permeability of the tonoplast.
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| 2. |
- Connolly, E, et al.
(författare)
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Na+-dependent, alpha-adrenergic mobilization of intracellular (mitochondrial) Ca2+ in brown adipocytes
- 1984
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 141:1, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- The existence and significance of a hormone-sensitive, rapidly mobilizable intracellular pool of Ca2+ in hamster brown-fat cells was investigated with 45Ca2+-labelling techniques. It was shown that such a pool existed and was probably located within the abundant mitochondria. It was rapidly mobilized by norepinephrine (median effective concentration 50 nM) through alpha-adrenergic mechanisms. The mobilization of Ca2+ from the intracellular stores (mitochondria) required the presence of extracellular Na+, but not of Ca2+, K+ or Mg2+. It is concluded that the experiments are in agreement with a hypothesis linking the mobilization of intracellular Ca2+ pools with an alpha-adrenergically-induced increase in plasma membrane Na+ permeability (observed as a membrane depolarization), and a subsequent activation of the mitochondrial Na+/Ca2+ exchange, leading to mobilization of mitochondrial Ca2+ and the mediation of alpha-adrenergic effects as a result of an elevated cytosolic Ca2+ level.
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| 3. |
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| 4. |
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| 5. |
- EDSTRÖM, Anders, et al.
(författare)
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Is protease activity involved in fast axonal transport?
- 1984
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 121:4, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- N‐a‐p‐Tosyl‐L‐Lysine Chloromethyl Ketone (TLCK), a protease inhibitor, was found to irreversibly inhibit rapid axonal transport of protein in vitro in the frog sciatic nerve. TLCK exerted its action at the axonal level and seemed to depress the rate rather than the amount of transported protein. The efficiency of TLCK as a protease inhibitor was demonstrated by polyacrylamide gel electrophoresis, which showed that degradation of high molecular weight proteins (presumably neurofilament subunits) into a 25 000 dalton protein could be induced by exposing the frog nerves to triton‐X and prevented by the presence of TLCK. Findings that TLCK, at a transport inhibiting concentration (0.1 mM), had little or no effects on either protein synthesis or ATP levels, suggest that TLCK did not affect transport due to general cytotoxic properties. The effects of TLCK is discussed in relation to possible roles of protease activity in axonal transport.
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| 6. |
- Edström, Anders, et al.
(författare)
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The use of the regenerating frog sciatic nerve for pharmacological studies of orthograde and retrograde axonal transport
- 1987
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 401:1, s. 34-42
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Tidskriftsartikel (refereegranskat)abstract
- The outgrowth region of the regenerating frog sciatic nerve shows an increased permeability for various drugs, which has been utilized for pharmacological studies of axonal transport. Six days after a bilateral crush lesion, the nerves, including the spinal ganglia, were incubated in a compartmented chamber. Orthograde transport was assessed from the proximodistal distribution and the accumulation of labelled proteins in the nerve growth region. Retrograde transport was examined by allowing orthogradely transported materials to reverse at the regenerating region and then to accumulate at a ligature during a second incubation period. The distribution of radioactivity along the nerve was assayed by fluorography of whole-mount nerve preparations or by scintillation counting. Fluorography made it possible to increase the spatial resolution and to demonstrate effects in the elongating part of the regenerating nerve. Colchicine at low concentrations (10-100 μM) only inhibited axonal transport in the outgrowth region (6 mm long at 6 days after crush) and along some mm of the nerve proximal to the crush. Compound 48/80 (50 μg/ml), the most specific calmodulin inhibitor so far described, inhibited the transport along the same part of the nerve. Cytochalasin B (10 μg/ml) inhibited transport by effects limited to the outgrowth region. Both orthograde and retrograde transport showed sensitivity to these and some other drugs. The regenerating frog sciatic nerve seems to have significant advantages for pharmacological studies of axonal transport.
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| 7. |
- Ekström, Per A R, et al.
(författare)
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Nerve regeneration and serum levels of insulin-like growth factor-I in rats with streptozotocin-induced insulin deficiency
- 1989
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 496:1-2, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- Peripheral nerve regeneration was studied in female Sprague-Dawley rats with streptozotocin-induced insulin deficiency. Nerve regeneration was provoked by a crush lesion on the sciatic nerve 21 days after the streptozotocin injection. The regeneration was assessed by a pinch test at different time-points after injury. The rate ofregeneration in insulin-deficient animals, 2.5 mm/day, was significantly lower than in control animals, 2.9 mm/day(P < 0.05). There was no difference in the initial delay, i.e. the period before regeneration attains a constant velocity. One group of insulin-deficient rats was treated with insulin during the regeneration period by means of implanted osmotic mini-pumps. This treatment prevented the decrease in regenerationsw. After 6 days the sciatic nerves of insulin-deficient rats had regenerated 12.3 ±0.3 mm (mean ±S.E.M.), while the corresponding value for insulin-treated rats was 15.7 ±0.6 mm (P > 0.01). The streptozotocin-treated rats were found to have a 39% reduction in the serum level of insulin-like 1 growth factor-I (IGF-I)_compared to control rats (0.33 ± 0.22 μg/ml and 0.54 ± ml respectively, (P < 0.001). Insulin treatment 1830 1732 during the regeneration period completely restored the IGF-I level back to normal.
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| 8. |
- Ekström, Per, et al.
(författare)
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Calmodulin‐Binding Proteins Within the Slow Phase of Axonal Transport in the Rabbit Vagus Nerve Per Ekstrom and Martin Kanje
- 1987
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 49:1, s. 146-151
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: : Calmodulin‐binding proteins (CBPs) in the rabbit vagus nerve were studied by means of calmodulin‐Sepha‐rose affinity chromatography and polyacrylamide gel electrophoresis. The soluble fraction (105g supernatant) of a nerve homogenate contained four CBPs with molecular weights of 44, 55, 91, and 93 kD, respectively. Slowly transported proteins were recovered in the vagus 3 days after injection of [35S]methionine into the nodose ganglion. Four labelled CBPs with molecular weights of 44, 55, 69, and 83 kD, respectively were found. The nodose ganglion con tained two labelled CBPs, 44 and 55 kD. The 55‐kD CBP was identified as tubulin after immunoblotting. In separate experiments it was also shown that bovine brain tubulin bound to the calmodulin column.
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| 9. |
- EKSTRÖM, Per, et al.
(författare)
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Effects of phenothiazines and dibenzazepines on axonal transport and microtubule assembly in vitro
- 1982
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 116:2, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- Various phenothiazines (thioridazine, trifluoperazine and chlorpromazine) and dibenzazepines (lofepramine, amitriptyline and desipramine) were studied for effects on fast axonal transport (AXT) in vitro in frog sciatic nerves. AXT, measured as the accumulation of (3H) leucine‐labelled proteins in front of a ligature, was inhibited by more then 50% by all the drugs tested at 0.2 mM concentrations. Thioridazine and lofepramine were the most potent inhibitors. These effects were not due to decreased ganglionic incorporation. Some of the drugs also reduced the levels of high energy phosphates, adenosinetriphosphate (ATP) and creatinephosphate (CrP), but not to an extent which is likely to explain the arrested AXT. The polymerization of purified brain tubulin was inhibited by the phenothiazines but unaffected by the dibenzazepines at concentrations which inhibited AXT. Phenothiazines and dibenzazepines are chemically related and known to have a high affinity for calmodulin. The possibility that these drugs interefere with calmodulin regulated processes of importance for AXT will be discussed.
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| 10. |
- Ekström, Per, et al.
(författare)
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Inhibition of Fast Axonal Transport by erythro‐9‐[3‐(2‐Hydroxynonyl)]Adenine
- 1984
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 43:5, s. 1342-1345
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: erythro‐9‐[3‐(2‐Hydroxynonyl)]adenine, an inhibitor of protein carboxylmethylation and dynein‐ATPase activity, inhibited fast axonal transport in vitro in frog sciatic nerves. Its site of action might be associated with an ATPase on which transport depends, since specific carboxylmethylation inhibitors lacked effects on transport. The levels of high energy phosphates and protein synthesis were unaffected by the drug at a transport‐inhibiting concentration, making disturbances due to metabolic effects less likely. An erythro‐9‐[3‐(2‐hy‐droxynonyl)]adenine‐sensitive ATPase was looked for in various nerve fractions but has so far not been resolved.
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