Effects of thrombin on intracellular calcium and pH in human and murine platelets.
The aim of this study was to compare the effect of thrombin (Thr) on cytosolic calcium [Ca2]+i and intracellular pH [pH]i in human and murine platelets. Rich-platelet suspensions from both species were loaded with Fura-2 (2 microM) or BCECF (0.75 microM) by incubation with their respective acetoxymethyl esters to measure cytosolic calcium [Ca2+]i or intracellular pH [pH]i, respectively. Suspensions were challenged with increasing concentrations of Thr, from 0.1 to 10 IU/ml. Basal [Ca2+]i in human platelets was 98 +/- 6 and 99.1 +/- 9 nM in rat platelets (n = 20). Thr increased [Ca2+]i, EC50 was 1.1 +/- 0.04 in human and 0.97 +/- 0.06 IU/ml in rat platelets (n = 7). Extracellular Mg2+ (4 or 8 mM) abolished Thr response on [Ca2+]i. [pH]i in human was 7.09 +/- 0.08 and 7.11 +/- 0.04 in rat platelets. Thr induced alkalinization of platelets in both species. Our results indicate that the potency of Thr to change [Ca2+]i and [pH]i was similar in both species, allowing for comparisons between human and murine platelets and to extrapolate results from an animal model to human pathology.
Department of Physiology and Biophysics, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., Mexico.
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Salazar
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Valencia
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Sierra
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Paniagua
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Melendez
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Reyes
D000328:Adult; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D005452:Fluoresceins; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007091:Image Processing, Computer-Assisted; D008274:Magnesium / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D013917:Thrombin / Q000494:pharmacology*
D005452:Fluoresceins; D005456:Fluorescent Dyes; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D013917:Thrombin; D008274:Magnesium; D002118:Calcium; D016257:Fura-2