[Experimental study of effects of cyclooxygenase-2 inhibitor on apoptosis of hypoxic myocardial cells in vitro].
OBJECTIVE
To observe the effects of cyclooxygenase (COX)-2 inhibitor on apoptosis of hypoxic myocardial cells in vitro.


METHODS
The myocardial cells were obtained from new-born Wistar rats, and were dispersed to single cell with trypsin. The cells in 4th-6th passages were randomly divided into 24 samples (every sample contained 1 x 10(5) cells): normal control group, hypoxic myocardial cells control group; hypoxic myocardial cells+NS-398 (20 micromol/L) and hypoxic myocardial cells+aspirin (100 microg/L). During culture, oxygen was replaced by N(2), and the cells were cultivated in 5% CO(2)+95% N(2) at 37 centigrade for 6 hours. Either interventional medicine or same amount of dimethyl sulphoxide was added to the cells 30 minutes before hypoxia. The expression of COX-1 and COX-2 in cultured myocardial cells in vitro was examined with Western blot. The apoptosis percentage of cells in each group was examined with flow cytometry. After centrifuging the culture medium under low temperature, 6-keto-prostaglandin F(1alpha) (6-keto-PGF(1alpha)) and thromboxane B(2) (TXB(2)) were determined with radioimmunoassay (RIA).


RESULTS
There was no significant difference in the expression of COX-1 among the groups. The expression of COX-2 was higher in all acute hypoxic myocardial cells groups compared with the control group. Neither aspirin nor NS-392 inhibited the expression of COX-2. The positive percentage of apoptosis of cultured myocardial cells ranked as follow: hypoxic+NS-398 group, hypoxic +aspirin group, hypoxic control group and normal control group. The differences of apoptosis rate between hypoxic+NS-398 group and other groups were significant (all P<0.05). The levels of TXB(2) in each group of cell medium ranked in the following order: normal control group, hypoxic +NS-398 group, hypoxic+aspirin group and hypoxic control group. The difference of TXB(2) level between hypoxic+NS-398 group and hypoxic control group was significant(P<0.05). The levels of 6-keto-PGF(1alpha) in each culture medium ranked in the following order: normal control group, hypoxic+aspirin group, hypoxic+NS-398 group and hypoxic control group. The difference between hypoxic+NS-398 group and hypoxic control group was significant (P<0.05). The ratio of TXB(2)/6-keto-PGF(1alpha) showed no significant difference (P>0.05) among groups.


CONCLUSIONS
The results suggest that acute hypoxia could directly induce cultured myocardial cells to express COX-2, but do not effect expression of COX-1. Hypoxia could elevate the level of 6-keto-PGF(1alpha) and TXB(2) in culture medium. COX-2 inhibitor (NS-398) could lessen the elevation, but it could not change the ratio between TXB(2) and 6-keto PGF(1alpha). NS-398 could increase apoptosis percentage of hypoxic myocardial cells in vitro, and the effect is independent of other inflammatory cells.
Yin
Ming
M
Institute of Geriatric Cardiology, Department of Emergency, General Hospital of PLA, Beijing 100853, China.
Shen
Hong
H
Li
Tan-shi
TS
Li
Yin-ping
YP
Liu
Gang
G
D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015687:Cell Hypoxia; D002478:Cells, Cultured; D051545:Cyclooxygenase 1 / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D005260:Female; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D013929:Thromboxane B2 / Q000378:metabolism
D052246:Cyclooxygenase 2 Inhibitors; D008565:Membrane Proteins; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496513:Ptgs1 protein, rat; C489691:Ptgs2 protein, rat