FACTORS INFLUENCING PLATELET SEROTONIN UPTAKE IN ESSENTIAL-HYPERTENSION

In a study of the mechanism(s) of platelet serotonin uptake alteration in essential hypertension, a total of 90 blood samples were analysed for platelet count and platelet serotonin uptake. These included 20 blood samples each of hypertensives, controls before and after cross-incubation experiments and 10 samples of hypertensives after control of blood pressure. It was observed that, serotonin uptake was markedly reduced in hypertensive platelets. Diminished serotonin uptake in essential hypertension correlated directly with diastolic and mean arterial blood pressure and inversely with plasma total cholesterol values. In cross-incubation experiments using control platelets and hypertensive plasma, there was a significant reduction in platelet serotonin uptake (303.06 +/- 86.28 cpm/10(8) vs. 204.26 +/- 66.45 cpm/10(8); P < 0.001), whereas hypertensive platelets when incubated with control plasma, showed increased serotonin uptake (233.50 +/- 75.19 cpm/10(8) vs. 312.64 +/- 79.54 cpm/10(8); P < 0.01). Upon control of blood pressure, the platelet serotonin uptake improved significantly (205.45 +/- 70.0 cpm/10(8) vs. 266.77 +/- 61.68 cpm/10(8); P < 0.05-0.01). From these results, it appears that reduced platelet serotonin uptake in essential hypertension is a reversible phenomenon probably governed by the presence of plasma factor(s) and/or altered platelet-membrane function.