Altered platelet phosphatidylinositol metabolism in essential hypertension

The metabolism of phosphoinositides was investigated in platelet membranes from nine patients with essential hypertension (EHT) and from 10 age/sex-matched normotensive subjects. 32P-labelling or phosphatidic acid (PA), phosphatidylinositol (PI), phosphatidylinositol-4-phosphate (PIP) and phosphatidylinositol-4,5-bisphosphate (PIP2) was measured in lipid extracts prepared from resting 32P-prelabelled platelets. There were no differences in 32P-PA between subject groups. In platelets of hypertensive patients, 32P-incorporation into both PIP and PIP2 was greater (P at least less than 0.01). This increase apparently occurred at the expense of lower 32P-incorporation into PI (P less than 0.001). An alteration in the interconversion equilibrium between phosphoinositides which is directed towards polyphosphoinositide formation may lead to altered membrane ionic fluxes.