Volume regulatory mechanisms of human platelets

Platelets were found to defend themselves against hypoosmotic swelling by a regulatory volume decrease mechanism, similar to that of T-lymphocytes. An oligomycin C sensitive Cl- -channel and a Ca2+-dependent, quinine- and trifluoperazine-sensitive K+-channel play a significant role in the process: platelets lose K+ and Cl- (and consequently water) through these. Activation of platelets accelerates the volume regulatory mechanism in spite of the fact that the Na+/H+ exchange process, activated simultaneously, works against volume decrease. The most rapid volume regulation was observed in activated platelets with inhibited Na+/H+ exchange process.