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.
Salazar
D
D
Department of Physiology and Biophysics, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, D.F., Mexico.
Valencia
L
L
Sierra
G
G
Paniagua
R
R
Melendez
E
E
Reyes
J L
JL
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