Effect of depletion of external Ca++ on ZT-A induced platelet activation
| Addition | MAPK [32P] (cpm/Tube) | Arachidonic Acid [3H] (dpm/5 × 108 Platelets) | [3H]IPs (dpm/5 × 108 Platelets) | TXB2 (ng/5 × 108Platelets) | |
|---|---|---|---|---|---|
| ZT-A | Ca++ | ||||
| − | + | 802 ± 96 | 1036 ± 108 | 1274 ± 30 | 0.87 ± 0.36 |
| + | + | 4534 ± 2252-a | 3854 ± 1572-a | 7562 ± 3872-a | 2.60 ± 0.712-a |
| − | − | 732 ± 70 | 693 ± 44 | 1018 ± 90 | 0.51 ± 0.03 |
| + | − | 725 ± 180 | 725 ± 33 | 1187 ± 99 | 0.44 ± 0.11 |
For determination of PI hydrolysis and arachidonic acid liberation, platelets were labeled with 25 μCi/ml [3H]myo-inositol and 10 μCi/ml [3H]arachidonic acid at 37°C for 1 hr, respectively. Platelets were incubated with ZT-A (2 μM) for 5 min in the presence of 1 mM CaCl2 or 1 mM EGTA. MAPK activity, PI hydrolysis, arachidonic acid liberation and TXB2 release that were not treated with ZT-A in the presence of 1 mM CaCl2 or 1 mM EGTA were taken as control, respectively. See “Methods and Methods” in detail. Values represent the mean ± S.E. (n = 4) and are representative of three independent experiments.
↵2-a Significant difference (P < .05) by unpairedt test when compared to control.