A major role for P2X₁ receptors in the early collagen-evoked intracellular Ca²⁺ responses of human platelets

Summary

In the platelet, ATP-gated P2X₁ receptors have been reported to amplify functional responses to collagen, however the relative importance of early Ca²⁺ mobilisation events is unknown. We now report that selective desensitisation of P2X₁ receptor activity leads to a major reduction in the initial intracellular Ca²⁺ responses to a wide range of collagen concentrations (0.25–2 μg ml^-1). Peak [Ca²⁺]_i increases were reduced to 8.5 and 55% of control, and the maximum rate of rise was reduced to 12 and 33% of control, at low and high collagen concentrations, respectively. This P2X₁-dependent acceleration and enhancement of collagen-stimulated Ca²⁺ responses was not observed in the absence of extracellular Ca²⁺. These results demonstrate a major role for ATP-gated Ca²⁺ influx in the early collagen-evoked Ca²⁺ signals and can at least partly explain the important contribution of P2X₁ receptors to arterial thrombosis.

Keywords

P2X₁ - ATP - collagen - Ca²⁺ - thrombosis

• References

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