[Hypoxia/reoxygenation-induced increased activity and expression of PTP-1B in neonatal rat cardiomyocytes are mediated by nitric oxide].
OBJECTIVE
To explore if the hypoxia/reoxygenation-induced increased activity and expression of PTP-1B in neonatal rat cardiomyocytes are mediated by nitric oxide (NO).


METHODS
Neonatal rat cardiomyocytes were isolated and randomly divided into 4 groups: normal group (N group); hypoxia/reoxygenation group (H/R group); N(omega)-nitro-l-arginine methylester treated group (L-NAME group); hypoxia/reoxygenation plus L-NAME group (L-NA + H/R group). PTP-1B activity in cardiomyocytes was determined spectrophotometrically at 405 nm, PTP-1B expression in cardiomyocytes was detected by Western blot.NO and LDH concentrations in cell medium were also assayed.


RESULTS
PTP-1B activity and expression in cardiomyocytes was significantly higher in the H/R group as compared to the N group and this increase could be blocked by cotreatment with L-NAME. As compared to H/R group, nitric oxide and LDH concentrations in cell medium were significantly decreased in the L-NA + H/R group (NO concentration: H/R group, 368% +/- 13% and L-NA + H/R group, 61% +/- 7%, P < 0.005; LDH concentration: H/R group, 41.2 +/- 6.7 and L-NA + H/R group, 23.6 +/- 4.8, P < 0.05).


CONCLUSIONS
This study showed that pretreatment with L-NAME, a non-selective inhibitor of NOS, prevented the hypoxia/reoxygenation-induced increase in PTP-1B activity and expression in cardiomyocytes, suggesting PTP-1B activation during hypoxia/reoxygenation was mediated by nitric oxide.
Song
Hui-wen
HW
Department of Cardiology, Tongji Hospital, Tongji Medical College of Huzahong University of Science and Technology, Wuhan 430030, China.
Wang
Lin
L
D000818:Animals; D015687:Cell Hypoxia; D002478:Cells, Cultured; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000378:metabolism*; D051381:Rats
D009569:Nitric Oxide; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D019331:NG-Nitroarginine Methyl Ester