Platelet cytosolic calcium hyperresponsivity to serotonin in patients with hypertension and depressive symptoms

Background: Data from recent studies indicate that the presence of depression is an independent risk factor for cardiovascular and cerebrovascular events. The mechanism by which depression increases the morbidity and mortality risks in patients with comorbid vascular disease is currently the object of considerable research interest. Platelets may be involved in this pathological process. Although many investigators have extensively evaluated platelet biochemistry in depressed patients, there currently exists very little information regarding how the biochemical alterations might relate to an increased risk of cardiovascular events. In this study, we examined the responsivity of platelet cytosolic calcium concentrations ([Ca++]i) to serotonin stimulation in populations of hypertensive patients with or without comorbid depressive symptoms. Methods: We utilized Fura-2 loaded platelets to compare changes in intracellular calcium levels (Δ[Ca++]i) following serotonin stimulation among 48 patients with hypertension and varying degrees of depressive symptomatology. Results: We found that those patients with higher scores on standardized depression rating scales showed significantly greater [Ca++]i (82.82 ± 15.88 mmol/L) increase compared with [Ca++]i (60.10 ± 22.65 mmol/L) patients with lower depression scores. Conclusions: The results of this study support the hypothesis that the enhanced platelet reactivity seen in patients with depressive symptoms may mediate the deleterious effects of depression on cardiovascular disease.