title: Inhibitory effects of total saponin from Korean Red Ginseng on [Ca(2+)]i mobilization through phosphorylation of cyclic adenosine monophosphate-dependent protein kinase catalytic subunit and inositol 1,4,5-trisphosphate receptor type I in human platelets.
abstract: BACKGROUND
  Intracellular Ca(2+)([Ca(2+)]i) is a platelet aggregation-inducing molecule. Therefore, understanding the inhibitory mechanism of [Ca(2+)]i mobilization is very important to evaluate the antiplatelet effect of a substance. This study was carried out to understand the Ca(2+)-antagonistic effect of total saponin from Korean Red Ginseng (KRG-TS).
  
  
  METHODS
  We investigated the Ca(2+)-antagonistic effect of KRG-TS on cyclic nucleotides-associated phosphorylation of inositol 1,4,5-trisphosphate receptor type I (IP3RI) and cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) in thrombin (0.05 U/mL)-stimulated human platelet aggregation.
  
  
  RESULTS
  The inhibition of [Ca(2+)]i mobilization by KRG-TS was increased by a PKA inhibitor (Rp-8-Br-cAMPS), which was more stronger than the inhibition by a cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) inhibitor (Rp-8-Br-cGMPS). In addition, Rp-8-Br-cAMPS inhibited phosphorylation of PKA catalytic subunit (PKAc) (Thr(197)) by KRG-TS. The phosphorylation of IP3RI (Ser(1756)) by KRG-TS was very strongly inhibited by Rp-8-Br-cAMPS compared with that by Rp-8-Br-cGMPS. These results suggest that the inhibitory effect of [Ca(2+)]i mobilization by KRG-TS is more strongly dependent on a cAMP/PKA pathway than a cGMP/PKG pathway. KRG-TS also inhibited the release of adenosine triphosphate and serotonin. In addition, only G-Rg3 of protopanaxadiol in KRG-TS inhibited thrombin-induced platelet aggregation.
  
  
  CONCLUSIONS
  These results strongly indicate that KRG-TS is a potent beneficial compound that inhibits [Ca(2+)]i mobilization in thrombin-platelet interactions, which may result in the prevention of platelet aggregation-mediated thrombotic disease.
authors: Department of Biomedical Laboratory Science, College of Biomedical Science and Engineering, Inje University, Inje-ro, Gimhae-si, Gyeongsangnam-do, Korea.
authors: Jung-Hae
authors: JH
authors: Shin
authors: Department of Biomedical Laboratory Science, College of Biomedical Science and Engineering, Inje University, Inje-ro, Gimhae-si, Gyeongsangnam-do, Korea.
authors: Hyuk-Woo
authors: HW
authors: Kwon
authors: Department of Biomedical Laboratory Science, College of Medical Science, Konyang University, Gasuwon-dong, Seo-gu, Daejeon, Korea.
authors: Hyun-Jeong
authors: HJ
authors: Cho
authors: Laboratory of Veterinary Physiology and Signaling, College of Veterinary Medicine, Kyungpook National University, Buk-gu, Daegu, Korea.
authors: Man Hee
authors: MH
authors: Rhee
authors: Department of Biomedical Laboratory Science, College of Biomedical Science and Engineering, Inje University, Inje-ro, Gimhae-si, Gyeongsangnam-do, Korea.
authors: Hwa-Jin
authors: HJ
authors: Park
keywords: Ca2+-mobilization; Panax ginseng; inositol 1,4,5-trisphosphate receptor type I (Ser1756) phosphorylation; protein kinase A catalytic subunit (Thr197) phosphorylation; total saponin from Korean Red Ginseng