【論文摘要】Role of T-type Calcium Channel in Platelet Function

Hem Tamang ； Chien-Chang Chen

《海峽循環醫學雜誌》 1卷2S期 (2019/09) Pp. 42-42

https://doi.org/10.6907/SCJ.201909/SP_1(2).0035

摘要

Background/Synopsis: Platelets play important role in hemostasis and wound healing. However, inappropriate aggregation of platelets during pathologic conditions may lead to myocardial infarction and stroke. Various calcium channels mediated increase in intracellular calcium concentration change during platelet activation is important for platelets activity. Role of low voltage activated T-type calcium channels (Cav3.1, Cav3.2 and Cav3.3) have been studied in various excitatory and non-excitatory cells. However, there is no report about the role of T-type calcium channels in platelets Objectives/Purpose: 1. To study the role of T-type calcium channel in platelet function 2. To elucidate the molecular mechanism 3. To study the effect of TTA-A2 ([2-(4-cyclopropylphenyl)-N-((1R)-1-{5-[(2,2,2-trifluoroethyl)oxo]pyridin-2-yl}ethyl), potent and selective T-type voltage gated calcium channel blocker, in platelet activity. Methods/Results: We developed transgenic mice (global Cav3.2 knockout and Platelet specific Cav3.2 knockout) to study the role of T-type calcium channel Cav3.2 in platelet activation and thrombosis. Blood flow during the thrombosis study was measured using the transonic Doppler probe. In addition, we used TTA-A2 as a pharmacological tool to investigate its effect in platelet activity. To investigate role of Cav3.2 in thrombosis we employed FeCl3 induced carotid artery thrombosis approach. Similarly, we used aggregometry to study platelet aggregation, bioluminescence assay to measure the platelet ATP release and ratiometric method for intracellular calcium measurement. For statistical analysis we used student's t-test and two way anova. The blood flow results recorded during the thrombosis study shows that deletion of Cav3.2 both globally and platelet specific leads to decreased FeCl3 injured carotid artery occlusive thrombus formation. However, tail bleeding results showed that Cav3.2 has no role in hemostasis. Interestingly, Cav3.2 deficient platelets and TTA-A2 treated platelets showed reduction in aggregation, ATP release and intracellular calcium concentration change when activated with collagen. Compared to controls, western blot results of both Cav3.2 deficient platelets and TTA-A2 treated platelets showed decreased phosphorylation of ERK and P38, indicating reduced calcium signaling. Conclusion: Deletion or inhibition of Cav3.2 may lead to reduced intracellular calcium change during platelet activation leading to decreased degranulation, aggregation and thrombosis.