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Basal and thrombin-stimulated platelet cell calcium
T M Dwyer1, K Diveki, G Newton
1Department of Physiology, University of Mississippi Medical Center, Jackson.
Insights
Canine platelet calcium concentration (Cai) was measured using fura-2 dye. Corrected Cai averages 40.5 nmol/L, significantly lower than uncorrected values, and influences thrombin-induced calcium transients.
Area of Science:
- Cardiovascular physiology
- Hematology
- Cellular biology
Background:
- Platelets play a crucial role in hemostasis and thrombosis.
- Intracellular calcium concentration (Cai) is a key regulator of platelet function.
- Accurate measurement of Cai is essential for understanding platelet activation.
Purpose of the Study:
- To determine the basal intracellular calcium concentration (Cai) in canine platelets.
- To investigate the impact of extracellular dye correction on Cai measurements.
- To assess the relationship between basal Cai and thrombin-induced calcium transients.
Main Methods:
- Blood samples were collected from four dogs via indwelling arterial catheters over 39 days.
- Platelet intracellular calcium concentration (Cai) was measured using fura-2 fluorescence.
- Measurements were performed with and without correction for extracellular fura-2 dye.
Main Results:
- Corrected canine platelet Cai averaged 40.5 ± 1.7 nmol/L (n=46).
- This value was significantly lower than uncorrected measurements (50.2 ± 2.0 nmol/L, P < .05).
- The amplitude of thrombin-induced Ca2+ transients was directly proportional to basal Cai.
Conclusions:
- Accurate Cai measurement in canine platelets requires correction for extracellular fura-2.
- Basal Cai levels directly influence the magnitude of platelet calcium responses to agonists like thrombin.
- These findings provide a more precise baseline for studying canine platelet calcium dynamics.
Abstract:
To study platelet cell calcium in dogs, we measured the fura-2-determined calcium concentration (Cai) in platelets derived from blood drawn through indwelling arterial catheters in four dogs. Platelet samples were obtained 3 days a week for 39 days. Canine platelet Cai averages 40.5 +/- 1.7 nmol/L when corrected for extracellular fura-2 dye (n = 46); this mean is significantly smaller than the value obtained without such a correction (50.2 +/- 2.0 nmol/L, P < .05). The amplitude of thrombin-induced Ca2+ transients is proportional to basal Cai, increasing 4.9 +/- 0.9 nmol/L peak Ca2+ per nmol/L increase in baseline Ca2+.