Modification of Na⁺/H⁺ Exchanger in Human Platelets by 1,2-Dioctanoylglycerol, a Protein Kinase C Activator

Summary

Protein kinase C activation in human platelets has a modulatory role in maintaining intracellular pH (pHi), by adjusting pHi at a particular value (7.22). Changes in pHi induced by protein kinase C appeared to be dependent upon the difference between H+ efflux catalyzed by the Na⁺/H⁺ exchanger and H⁺ production. The pHi recovery after acid loading was significantly facilitated by protein kinase C activation. Analysis of the rate constant for pHi recovery suggested that the turnover rate or the apparent affinity of the Na⁺/H⁺ exchanger for H⁺ was increased. Protein kinase C also decreased the Km value of the Na⁺/H⁺ exchanger for extracellular Na⁺. Thus, it is suggested that the role of protein kinase C in platelet pHi regulation is dual, adjusting the pHi value at a certain setpoint on the one hand, and increasing the rate constant of the Na⁺/H⁺ exchanger on the other.

• References

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