TMB-8 inhibits secretion evoked by phorbol ester at basal cytoplasmic free calcium in quin2-loaded platelets much more effectively than it inhibits thrombin-induced calcium mobilisation |
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Authors: | A W Simpson T J Hallam T J Rink |
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Institution: | 1. Catedra de Química Biológica, Facultad de Medicina, Paraguay 2155, 5 Piso, 1121 Capital Federal, Buenos Aires Argentina;2. Centro de Investigaciones Bioenergéticas, Facultad de Medicina, Paraguay 2155, 5 Piso, 1121 Capital Federal, Buenos Aires Argentina;3. Instituto Nacional de Diagnóstico e Investigación Dr M.F. Chaben, Buenos Aires, Argentina |
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Abstract: | TMB-8 is widely regarded as an 'intracellular calcium antagonist', supposedly inhibiting the mobilisation of intracellular calcium. Rarely, however, have the effects of this compound on Ca2+ movements been measured. We report here that TMB-8 is not very effective in inhibiting thrombin-induced Ca2+ influx or internal release in human platelets judged from the fluorescent signal of cytoplasmic quin2. Only approx. 40% inhibition was seen at 500 microns TMB-8. Somewhat lower concentrations blocked the secretory response to thrombin and also the secretion evoked at basal Ca2+]i by phorbol ester and collagen. It is suggested that one target for TMB-8 may be the C-kinase pathway. |
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Keywords: | Kinetoplast DNA Minicircle Minicircle cloning Isolate-specific minicircle Isolate identification kDNA kinetoplast DNA SSC 150 mM NaCl/15 mM sodium citrate kb kilobasepairs |
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