Effects of tetramethylpyrazine on the release of PGI2 and TXA2 in the hypoxic isolated rat heart.

We examined the effect on 6-Keto-PGF1a and TXB2 (the stable metabolites of PGI2 and TXA2) outflow of pretreatment with tetramethylpyrazine in the hypoxic isolated rat heart. In control hearts, 6-Keto-PGF1a was increased from 185 +/- 46 pg/ml of baseline value to 335 +/- 76 pg/ml after 2 min of hypoxia and TXB2 increased from 136 +/- 28 pg/ml of baseline value to 230 +/- 43 pg/ml at 20 min of hypoxia and 252 +/- 32 pg/ml after 5 min of reoxygenation. Pretreatment with tetramethylpyrazine increased the 6-Keto-PGF1a concentration to 266 +/- 51 pg/ml (143% of control heart), 471 +/- 89 pg/ml (150% of control heart) and 332 +/- 47 pg/ml (195% of control heart) at 15 min of normoxia, 2 min of hypoxia and 5 min of reoxygenation, respectively (p < 0.05 vs control). On the other hand, tetramethylpyrazine diminished the release of TXB2 to 78 +/- 21 pg/ml (174% of control heart), 160 +/- 30 pg/ml (144% of control heart), and 196 +/- 23 pg/ml (128% of control heart) at 15 min of normoxia, 20 min of hypoxia and 5 min of reoxygenation, respectively (p < 0.05 vs control). These data show that pretreatment with tetramethylpyrazine enhances PGI2 outflow and attenuates release of TXA2 in the rat heart during normoxia, hypoxia and reoxygenation.