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B T Pickering

Publications and source records attributed to B T Pickering.

At least 55 records · Page 3Linked to original sources
PubMed1976

Incorporation of radioactive precursors into the membrane and contents of the neurosecretory granules of the rat neurohypophysis as a method of studying their fate.

Rat neural lobes have been separated into subcellular fractions by differential centrifugation at various times after an intracisternal injection of [35S]cysteine or [3H]choline. Both isotopes led to a rise and fall in the radioactivity of neurosecretory granules (NSG) which paralleled that found previously for the neurohypophysial hormones and the neurophysins. While the radioactivity of the NSGs resulting from [35S]cysteine injection was predominantly associated with granular contents, [3H]choline injections led to a preferential labelling of the granular membrane. There was no indication of a sequential movement of radioactivity from the NSG-membrane fraction into the microsomal fraction (containing the so-called small vesicles) which might be expected if granular membrane were recaptured as small vesicles after release of secretory product by exocytosis. When release was stimulated in injected animals by giving them 2% NaCl solution to drink, 35S diappeared from the gland as expected, but 3H was retained and, moreover, appeared in the NSG-membrane fraction; results compatible with membrane conservation occurring by recapture of large vesicles. There was an indication that some of the neurophysin in the NSG was membrane-bound and that this too was retained after release of the granular contents.

Animals↗
PubMed1975

Movement of neurosecretory product through the anatomical compartments of the neural lobe of the pituitary gland. An electron microscopic autoradiographic study.

Electron-microscope autoradiographs have been prepared from the neural lobes of the pituitary glands of rats which had received intracisternal injections of [35S] cysteine at various times before gland removal. The rate of appearance and disappearance of autoradiographically demonstrable radioactivity in the neural lobe closely paralleled that previously determined, biochemically, for radioactive hormones and neurophysins. Radioactivity was appreciably associated with the undilated parts of neurosecretory axons only during the first few hours after injection of the label. The axonal dilations were subdivided into those in which small vesicles could be seen ("endings") and those in which no small vesicles could be seen ("swellings"). Radioactivity appeared first in "endings" and then in progressively larger and larger profiles of "swellings". It appeared that newly arrived granules were found close to the limiting membrane of the nerve swelling and that as time progressed they moved deeper and deeper into the swelling. On the basis of the results, suggestions were made for an anatomical explanation of the readily-releasable pool of hormone which has been demonstrated pharmacologically.

Animals↗
PubMed1975

Endocrine neurons.

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Action Potentials↗
PubMed1973

Intra-axonal transport and turnover of neurophysins in the rat. A proposal for a possible origin of the minor neurophysin component.

1. Radioactivity associated with the three neurophysins in the neural lobe of the rat was determined at intervals up to 5 weeks after an intracisternal injection of [(35)S]cysteine. 2. The radioactivity associated with the two major neurophysins (one supposedly associated with vasopressin and the other with oxytocin) increased linearly for 12h after the injection and the ratio of the rates of increase in the two proteins was very similar to the ratio of vasopressin to oxytocin in the gland. 3. From 12h onwards the radioactivity associated with each major neurophysin declined exponentially but the half-life of the supposed oxytocin-neurophysin (13.3 days) was shorter than that for the supposed vasopressin-neurophysin (19.8 days). 4. The kinetics of labelling of the minor neurophysin was quite different from that of the two major ones. It became slowly labelled during 3-5 days after injection and the radioactivity hardly decreased during the following 4 weeks. 5. The data could support the hypothesis that the minor neurophysin is a metabolic product of oxytocin-neurophysin. The exponential rate of disappearance of radioactivity from oxytocin-neurophysin and the minor component taken together has a rate constant similar to that for vasopressin-neurophysin (e.g. half-life=18.9 days).

Animals↗
PubMed1972

The number of neurophysins in the rat. Influence of the concentration of Bromophenol Blue, used as a tracking dye, on the resolution of proteins by polyacrylamide-gel electrophoresis.

1. The concentration of Bromophenol Blue used as tracking dye in polyacrylamide-gel electrophoresis affected the resolution of rat neurophysins. 2. A final dye concentration of 1mug/ml in the tris-glycine running buffer was found to give the best results. 3. The presence of two major and one minor neurophysin(s) in the rat was confirmed. 4. The two major proteins were found to re-run as single discrete bands, which had the same mobilities in the absence of dye and different mobilities in its presence.

Animals↗
PubMed1972

Intra-axonal transport and turnover of neurohypophysial hormones in the rat.

1. The specific radioactivities of isotopically pure oxytocin and vasopressin prepared from the neural lobe of the pituitary gland have been measured at various times after an intracisternal injection of [(3)H]tyrosine.2. Radioactive hormone began to appear in the gland 1-2 hr after the injection which suggests an intra-axonal transport velocity of 1-2 mm/hr.3. From 7 days onwards the specific radioactivity of each hormone declined exponentially with the same rate constant and a half-life of about 13 days.4. If the decline in radioactivity can be equated with the release of the hormones, the rates of secretion for the male rat in water balance are 18.7 m-u./day for oxytocin and 28.9 m-u./day for vasopressin.5. Calculation from the secretion rates gave steady-state plasma concentrations of about 3 muu./ml. for each hormone.

Animals↗