Endothelin-1 evoked an increase and oscillations in cytosolic calcium concentration in adherent single human platelets and increased GMP-140 (P-selectin) in platelet suspension.
The effect of endothelin-1 (ET-1) on cytosolic calcium ion concentration ([Ca2+]i) in adherent single human blood platelet was determined by fluorescence digital imaging microscopy using Fura-2 as calcium probe. A dose dependent increase and oscillatory changes in [Ca2+]i in single platelets were evoked by ET-1 as with thrombin. Half and 1 microM of ET-1 increased (p < 0.01) the [Ca2+]i in single platelets from a resting level of 83 +/-3.4 nM to 120 +/- 13 nM and 240 +/- 20 nM respectively. The ET-1 induced increase in [Ca2+]i was suppressed by 1 mM EGTA, a calcium chelating agent in the medium. ET-1 increased the production of IP3 (quantitified by IP3 3H-radioreceptor assay kit) in platelets significantly (p < 0.05) in a dose dependent way. We measured the GMP-140 (P-selectin) level in the supernatant of human platelet suspensions incubated with thrombin and ET-1. Both thrombin and ET-1 increased the secretion of soluble GMP-140 in the supernatant of platelet suspensions. Therefore, we suggested that ET-1 increased [Ca2+]i in platelets by both calcium influx and IP3 mediated Ca2+ release resulting in activation and release of GMP-140.
Halim
A
A
Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Japan.
Kanayama
N
N
el Maradny
E
E
Maehara
K
K
Hirano
M
M
Kobayashi
T
T
Terao
T
T
D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D003600:Cytosol / Q000378:metabolism*; D016232:Endothelins / Q000494:pharmacology*; D006801:Humans; D008856:Microscopy, Fluorescence; D019007:P-Selectin / Q000097:blood*
D016232:Endothelins; D019007:P-Selectin; D002118:Calcium