Menthol, a natural compound, is responsible for the minty flavor and smell of the mint plant and is widely used in food and drugs. A recent study showed that menthol modifies PLC signaling, which then leads to changes in cellular functions. Platelet dysfunction plays an important role in thrombosis in diabetes with peripheral artery disease (PAD). Store-operated calcium entry (SOCE) and stromal interaction molecule 1 (STIM1) regulate platelet activity by modulating calcium influx. We hypothesized that enhanced SOCE in platelets is associated with diabetes with PAD.Design and Method:
We studied the activity of platelets from healthy participants (NT), type 2 diabetic patients (DM) and hypertension with type 2 diabetes (HDM). Platelet calcium influx and protein expression of STIM1 and sarcoendoplasmic reticulum Ca2+-ATPase 3 (SERCA3) were investigated.Results:
Compared with that in platelets from DM, calcium influx was significantly increased in platelets from HDM in the absence of extracellular calcium after the discharge of intracellular Ca2+ stores by thapsigargin. Compared with platelets from DM without PAD, platelets from DM with PAD exhibited significantly increased SOCE. Menthol administration completely inhibited calcium influx in platelets from diabetic patients without PAD, but this effect was blunted in those from diabetic patients with PAD. Furthermore, the increased SOC calcium influx was correlated with the ankle brachial index (ABI) in diabetic patients. High glucose significantly up-regulated STIM1 and SERCA3 protein expression and induced the phosphorylation of phospholipase C (PLC) in platelets from healthy participants. This effect was attenuated in the presence of menthol or U73122, an inhibitor of PLC. Similarly, significant increases in STIM1 and SERCA3 protein expression were found in platelets from diabetic patients compared to those from healthy participants.Conclusions:
Platelets from hypertension diabetic patients with PAD exhibited enhanced Store-operated calcium influx, which was associated with elevated STIM1/SERCA3 expression via a PLC-dependent pathway and was inhibited by menthol.