[Effects of docosahexaenoic acid on action potential and transient outward potassium current on ventricular myocytes of Sprague-Dawley rat].
OBJECTIVE
To investigate the effects of docosahexaenoic acid (DHA) on action potential (AP) and transient outward potassium current (I(to)) on ventricular myocytes of Sprague-Dawley rat.


METHODS
Calcium-tolerant ventricular myocytes were isolated by enzyme digestion. The changes of AP and I(to) with increasing DHA at concentrations of 0, 10, 20, 40, 60, 80, 100, 120 and 200 micromol/L were recorded by whole-cell patch clamp configuration.


RESULTS
(1) Action potential durations (APDs) were not affected by DHA at concentrations from 0 micromol/L to 30 micromol/L, while APDs were gradually prolonged in proportion with increasing DHA concentrations from 30 micromol/L to 200 micromol/L within 5 minutes and remained stable thereafter. APD(25), APD(50) and APD(75) were (7.7 +/- 2.0) ms, (21.2 +/- 3.5) ms, and (100.1 +/- 9.8) ms respectively at 100 micromol/L DHA. APD(25), APD(50), and APD(75) were (15.2 +/- 4.0) ms, (45.7 +/- 6.8) ms, and (215.6 +/- 15.7) ms respectively at 200 micromol/L DHA. (2) I(to) was gradually reduced with the increasing DHA concentrations from 10 micromol/L to 200 micromol/L. I(to) was blocked by DHA in a dose-dependent manner. I(to) current density was (30.1 +/- 7.2) pA/pF at DHA concentration of 60 micromol/L and its half-inhibition concentration was 58.3 micromol/L.


CONCLUSIONS
APDs are gradually prolonged while I(to) reduced with increasing concentrations of DHA which might contribute to the anti-arrhythmia mechanisms of DHA.
Wang
Ru-Xing
RX
Department of Cardiology, Affiliated Wuxi People's Hospital of Nanjing Medical University, Wuxi 214023, China.
Li
Xiao-Rong
XR
Lai
Li-Hong
LH
Wu
Xiao-Qing
XQ
Chen
Yan-Fen
YF
Song
Jian-Ping
JP
Yang
Xiang-Jun
XJ
Jiang
Wen-Ping
WP
D000200:Action Potentials; D000818:Animals; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D024661:Potassium Channels, Inwardly Rectifying; D004281:Docosahexaenoic Acids