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Digitale Medien

Photoactivation of intracellular guanosine triphosphate analogues reduces the amplitude and slows the kinetics of voltage-activated calcium channel currents in sensory neurones (1988)

Dolphin, A. C. ; Wootton, J. F. ; Scott, R. H. ; [weitere]

Springer

Pflügers Archiv 411 (1988), S. 628-636

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ISSN: 1432-2013

Schlagwort(e): Guanine nucleotide analogue ; Calcium current ; Flash photolysis ; Guanine nucleotide binding protein ; dorsal root ganglion neurone

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract The influence of guanine nucleotide analogues on calcium channel currents in cultured rat dorsal root ganglion neurones has been studied using a technique in which the rate of diffusion of the analogues to their site of action is by-passed by photochemical release of the analogues within the neurones. The 1(2-nitrophenyl)ethyl P3-ester derivatives of guanosine 5′-0(3-thio)triphosphate (caged GTP-γ-S) and 5′-guanylylimidodiphosphate (caged GMP-PNP) were synthesised and found to be completely photolysable by light, yielding free GTP-γ-S and GMP-PNP. Calcium channel currents were recorded using the whole cell patch technique and either caged GTP-γ-S or caged GMP-PNP (2 mM) were included in the patch pipette. Stable currents were recorded for 5–10 min, and a single pulse of 300–350 nm irradiation was directed using a liquid light guide onto the recording dish. Calcium channel currents were then recorded every 30–120 s following photochemical release of approximately 20μM GTP-gg-S. The peak calcium channel current was reduced by about 70% with a slow time course [t 1/2 1.5±0.2 min (mean±SEM);n=5]. The transient component of the peak current was usually completely abolished, whereas the sustained current measured at the end of the 100 ms depolarising pulse was less affected. Qualitatively similar effects were observed on photolysis of caged GMP-PNP. These results suggest that the channels underlying the transient and the sustained components of the whole cell current may be differentially molulated by GTP analogues.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00580858

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Digitale Medien

Single photon counting imagery (1989)

Scott, R. Q. ; Inaba, Humio

New York : Wiley-Blackwell

Journal of Bioluminescence and Chemiluminescence 4 (1989), S. 507-511

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Details

ISSN: 0884-3996

Schlagwort(e): Chemistry ; Biochemistry and Biotechnology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Chemie und Pharmazie

Notizen: Advent of the multichannel plate and position sensitive detector has made possible true single photon counting imaging tubes. We have investigated the application of these detectors in studies of the ultraweak light emission of biological materials. Initially, we focussed our efforts on two objectives: (1) obtaining single photon counting images of living tissues using only the light (chemiluminescence) emitted by the specimen and (2) developing means of obtaining well-resolved spectra of weakly emitting sources. We have obtained a variety of images. One striking result of this work is the first observation of tissue specific localization of photon emission in situ. Using this detector we have also obtained the first well-resolved spectra of some important ultraweak emission processes. These results illustrate the potential use of single photon imaging in bioluminescence and chemiluminescence research.

Zusätzliches Material: 4 Ill.