scholarly journals L-Type Ca2+ Channel Responses to Bay K 8644 in Stem Cell-Derived Cardiomyocytes Are Unusually Dependent on Holding Potential and Charge Carrier

2014 ◽  
Vol 12 (6) ◽  
pp. 352-360 ◽  
Author(s):  
Junzhi Ji ◽  
Jiesheng Kang ◽  
David Rampe
Keyword(s):  
2004 ◽  
Vol 92 (2) ◽  
pp. 824-837 ◽  
Author(s):  
Steven J. Tavalin ◽  
Dawn Shepherd ◽  
Robin K. Cloues ◽  
Sarah E. H. Bowden ◽  
Neil V. Marrion

The influx of calcium (Ca2+) ions through L-type channels underlies many cellular processes, ranging from initiation of gene transcription to activation of Ca2+-activated potassium channels. L-type channels possess a diagnostic pharmacology, being enhanced by the dihydropyridine BAY K 8644 and benzoylpyrrole FPL 64176. It is assumed that the action of these compounds is independent of the ion conducted through the channel. In contrast to this assumption, modulation of L-type channel activity in acutely dissociated rat CA1 hippocampal neurons depended on the divalent ion identity. BAY K 8644 and FPL 64176 substantially increased single-channel open time only when barium (Ba2+) was the permeant ion. BAY K 8644 increased single-channel conductance when either Ba2+ or Ca2+ ions were the charge carrier, an effect not observed with FPL 64176. BAY K 8644 enhanced the whole cell L-type channel Ca2+- or Ba2+-carried current without a change in deactivation tail kinetics. In contrast, enhancement by FPL 64176 was associated with a dramatic slowing of deactivation kinetics only when Ba2+ and not Ca2+ was the charge carrier. Current activation was slowed by FPL 64176 with either charge carrier, an effect arising from a clustering of agonist-modified long-duration openings toward the end of the voltage step. These data indicate that agonists enhanced L-type current by distinct mechanisms dependent on the permeant ion, indicating that care must be considered when used as diagnostic tools.


2020 ◽  
Author(s):  
Min Ji Han ◽  
Won Ji Lee ◽  
Joonhyuk Choi ◽  
Yean Ju Hong ◽  
Sang Jun Uhm ◽  
...  

Author(s):  
D.E. Philpott ◽  
W. Sapp ◽  
C. Williams ◽  
J. Stevenson ◽  
S. Black ◽  
...  

Spermatogonial stem-cell survival after irradiation injury has been studied in rodents by histological counts of surviving cells. Many studies, including previous work from our laboratory, show that the spermatogonial population demonstrates a heterogeneous response to irradiation. The spermatogonia increase in radio-sensitivity as differentiation proceeds through the sequence As - Apr - A1 - A2 - A3 - A4 - In - B. The stem (As) cell is the most resistant and the B cell is the most sensitive. The purpose of this work is to investigate the response of spermatogonial cell to low doses (less than 10 0 rads) of helium particle irradiation.


Author(s):  
D. E. Philpott ◽  
W. Sapp ◽  
C. Williams ◽  
Joann Stevenson ◽  
S. Black

The response of spermatogonial cells to X-irradiation is well documented. It has been shown that there is a radiation resistent stem cell (As) which, after irradiation, replenishes the seminiferous epithelium. Most investigations in this area have dealt with radiation dosages of 100R or more. This study was undertaken to observe cellular responses at doses less than 100R of X-irradiation utilizing a system in which the tissue can be used for light and electron microscopy.Brown B6D2F1 mice aged 16 weeks were exposed to X-irradiation (225KeV; 15mA; filter 0.35 Cu; 50-60 R/min). Four mice were irradiated at each dose level between 1 and 100 rads. Testes were removed 3 days post-irradiation, fixed, and embedded. Sections were cut at 2 microns for light microscopy. After staining, surviving spermatogonia were identified and counted in tubule cross sections. The surviving fraction of spermatogonia compared to control, S/S0, was plotted against dose to give the curve shown in Fig. 1.


Author(s):  
Eric Hallberg ◽  
Lina Hansén

The antennal rudiments in lepidopterous insects are present as disks during the larval stage. The tubular double-walled antennal disk is present beneath the larval antenna, and its inner layer gives rise to the adult antenna during the pupal stage. The sensilla develop from a cluster of cells that are derived from one stem cell, which gives rise to both sensory and enveloping cells. During the morphogenesis of the sensillum these cells undergo major transformations, including cell death. In the moth Agrotis segetum the pupal stage lasts about 14 days (temperature, 25°C). The antennae, clearly seen from the exterior, were dissected and fixed according to standard procedures (3 % glutaraldehyde in 0.15 M cacaodylate buffer, followed by 1 % osmiumtetroxide in the same buffer). Pupae from day 1 to day 8, of both sexes were studied.


2000 ◽  
Vol 111 (3) ◽  
pp. 890-897 ◽  
Author(s):  
Timm Schroeder ◽  
Claudia Lange ◽  
John Strehl ◽  
Ursula Just

2010 ◽  
Vol 41 (7) ◽  
pp. 6
Author(s):  
DOUG BRUNK
Keyword(s):  

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