Antagonism of endothelin-1 inhibits hypoxia-induced apoptosis in cardiomyocytes.

Abstract

Apoptosis is well documented to be a common feature of many pathological processes of the heart. Exogenous endothelin-1 (ET-1) has been shown to be proapoptotic or antiapoptotic, depending on ET-1 concentration, cell type, and the ratio of ETA/ETB receptor subtypes. The role of endogenous ET-1 in cardiomyocyte apoptosis, however, is not clarified. This study observed the effects of the ETA-receptor antagonists BQ610 and BQ123 and the ETB-receptor antagonist BQ788 on hypoxia-induced apoptosis in primary cultured neonatal rat cardiomyocytes. Hypoxic apoptosis was induced by incubating cardiomyocytes in serum-free medium under 3% O2 and 5% CO2 for 24 h and evaluated by TUNEL analysis and flow cytometry. TUNEL analysis showed that the apoptotic cardiomyocytes constituted 24.2% +/- 2.2% of the total cells under hypoxic conditions. Treatment with BQ610 (5 micromol/L) significantly reduced the apoptosis rate to 13.2% +/- 3.7% (data from 4 independent experiments, p < 0.01 vs. hypoxia). Flow cytometry showed that the percentage of apoptotic cells positively stained with annexin V and propidium iodide was 42.76% +/- 4.44% (n = 12) in cultures subjected to hypoxia. BQ123 at 0.04, 0.2, and 1.0 micromol/L dose-dependently reduced the apoptosis rate to 34.00% +/- 10.35% (n = 6, p < 0.05), 30.38% +/- 8.28% (n = 6, p < 0.01), and 22.89% +/- 4.19% (n = 6, p < 0.01), respectively. In contrast, BQ788 did not affect hypoxic apoptosis. These findings suggested that endogenous ET-1 contributed to hypoxia-induced apoptosis in cultured cardiomyocytes, which was mediated by ETA receptors, but not by ETB receptors.

• Authors: Anjing Ren, Xiaohong Yan, Hong Lu, Jingsong Shi, Yuanjun Yin, Jie Bai, Wenjun Yuan, Li Lin
• Journal: Canadian journal of physiology and pharmacology (Can J Physiol Pharmacol) Vol. 86 Issue 8 Pg. 536-40 (Aug 2008) ISSN: 0008-4212 [Print] Canada
• PMID: 18758501 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Endothelin A Receptor Antagonists
• Endothelin B Receptor Antagonists
• Endothelin-1
• Oligopeptides
• Peptides, Cyclic
• Piperidines
• BQ 610
• BQ 788
• L-Lactate Dehydrogenase
• Superoxide Dismutase
• cyclo(Trp-Asp-Pro-Val-Leu)

Topics

• Animals
• Animals, Newborn
• Apoptosis (drug effects)
• Cell Hypoxia (drug effects)
• Dose-Response Relationship, Drug
• Endothelin A Receptor Antagonists
• Endothelin B Receptor Antagonists
• Endothelin-1 (antagonists & inhibitors)
• Flow Cytometry
• In Situ Nick-End Labeling
• L-Lactate Dehydrogenase (metabolism)
• Myocytes, Cardiac (drug effects)
• Oligopeptides (pharmacology)
• Peptides, Cyclic (pharmacology)
• Piperidines (pharmacology)
• Rats
• Rats, Sprague-Dawley
• Superoxide Dismutase (metabolism)