Tetramethylpyrazine as potassium channel opener to lower calcium influx into cultured aortic smooth muscle cells.
In the present study, the effect of tetramethylpyrazine (TMP) on calcium (Ca 2+) influx was investigated in cultured vascular smooth muscle (A7r5) cells using Fura-2 as an indicator. The increase of Ca 2+ concentration in A7r5 cells produced by vasopressin or phenylephrine was attenuated by TMP from 0.01 micromol/L to 1 mmol/L. The decrease in the intracellular potassium concentration in A7r5 cells by TMP from 0.01 micromol/L to 10 micromol/L was characterized using PBFI/AM. Inhibitors specific to the small conductance calcium-activated potassium (SKCa ) channel or the ATP-sensitive potassium (K ATP ) channel abolished the actions of TMP. The obtained results indicate that the decrease of Ca 2+ influx into A7r5 cells by TMP is mainly mediated by the opening of potassium channels.
Tsai
Chin-Chuan
CC
Department of Traditional Medicine, School of Post-Baccalaureate Chinese Medicine, China Medical College, Taichung City, Taiwan. tsaic@mail.cmc.edu.tw
Lai
Tung-Yuan
TY
Huang
Wei-Chan
WC
Yang
Tzyylin
T
Liu
I-Min
IM
Wong
Kar-Lok
KL
Chan
Paul
P
Cheng
Juei-Tang
JT
D000818:Animals; D001011:Aorta / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal; D030004:Ligusticum; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D008517:Phytotherapy; D015221:Potassium Channels / Q000378:metabolism*; D011719:Pyrazines / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
D004365:Drugs, Chinese Herbal; D015221:Potassium Channels; D011719:Pyrazines; D014665:Vasodilator Agents; C101574:chuangxiong extract; D002118:Calcium; C017953:tetramethylpyrazine