A flow cytometric analysis of the inhibition of platelet reactivity due to nitrite reduction by deoxygenated erythrocytes
Nitric oxide (NO), a small gas molecule, has long been known to be a potent inhibitor of platelet function but the physiological and pathological implications of platelet inhibition by NO have not been well clarified. We recently showed that the addition of nitrite to platelet-rich plasma in the p...
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Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
2015
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Online Access: | https://repository.li.mahidol.ac.th/handle/123456789/1847 |
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Institution: | Mahidol University |
Language: | English |
Summary: | Nitric oxide (NO), a small gas molecule, has long been known to be a potent inhibitor of platelet function but the
physiological and pathological implications of platelet inhibition by NO have not been well clarified. We recently showed
that the addition of nitrite to platelet-rich plasma in the presence of erythrocytes could inhibit platelet aggregation and this
inhibitory effect of nitrite + erythrocytes was enhanced by deoxygenation of erythrocytes as measured by P-selectin
expression and cGMP production. In order to study the nitrite effect on platelets at different oxygen levels, we used the flow
cytometric assays to detect platelet membrane surface markers upon activation. The P-selectin and activated gpIIb/IIIa
expression on platelet membranes in response to ADP, collagen and thrombin stimulation was measured at various
hematocrit and oxygen levels. Nitrite (0.1 to 1.0 mM) significantly decreased the percentage of these surface markers on the
platelet membrane at the hematocrit values above 23% and oxygen levels lower than 49 mmHg. The inhibitory effect of
nitrite was augmented by increasing hematocrit values and decreasing oxygen saturation. C-PTIO (an NO scavenger)
prevented the platelet inhibition by nitrite + erythrocytes whereas the inhibitors of NO synthase and xanthine
oxidoreductase had no effect. These results support the proposal that circulating nitrite decreases platelet reactivity in the
presence of partially deoxygenated erythrocytes through its reduction to NO, which may also explain certain differences
between arterial and venous thrombosis and support directly the role of deoxyhemoglobin in this process. We believe that
our flow cytometric assays offer a possibility to identify the individual molecular process involved in these effects. |
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