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Published on: May 19, 2017
Endothelin-1 prolongs intracellular calcium transient decay in neonatal rat cardiac myocytes
Yoshiki Uehara1, Yoshiyuki Azuma, Kosuke Minai
1Division of Cardiology, Department of Internal Medicine, The Jikei University Kashiwa Hospital, 163-1, Kashiwashita, Kashiwa, Chiba, 277-8567, Japan. yuehara@jikei.ac.jp
Insights
Endothelin-1 (ET-1) prolongs calcium transient decay in cardiomyocytes by reducing sarcoplasmic reticulum calcium uptake. This occurs via the ETA receptor and PKC pathway, suggesting ETA receptor inhibition as a therapeutic approach for heart failure.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Cell Physiology
Background:
- Endothelin-1 (ET-1) plays a role in cardiac hypertrophy and heart failure.
- Intracellular calcium handling is critical for cardiac function.
Purpose of the Study:
- To investigate the effects of ET-1 on intracellular calcium transient decay in cardiomyocytes.
- To elucidate the underlying mechanisms of ET-1-induced alterations in calcium handling.
Main Methods:
- Primary neonatal rat cardiomyocyte culture.
- Measurement of intracellular calcium transient using fura-2.
- Northern blotting and real-time RT-PCR for gene expression analysis.
- Pharmacological inhibition of specific pathways (thapsigargin, sodium removal, BQ-123, BQ-788, chelerythrine, phorbol 12-myristate 13-acetate).
Main Results:
- ET-1 treatment prolonged calcium transient decay.
- This prolongation was attributed to suppressed sarcoplasmic reticulum calcium uptake, not sodium/calcium exchanger inhibition.
- ET-1 decreased sarcoplasmic reticulum ATPase (SERCA2) mRNA expression via the ETA receptor and protein kinase C (PKC) pathway.
- ETA receptor gene expression was abundant in cardiomyocytes.
Conclusions:
- ET-1 prolongs intracellular calcium transient decay by reducing SERCA2 gene expression through the ETA receptor and PKC pathway.
- Specific inhibition of the ETA receptor may offer a therapeutic strategy for improving cardiac performance in conditions like heart failure.
Abstract:
Endothelin-1 (ET-1) is involved in the development of cardiac hypertrophy and heart failure. We investigated the effects of ET-1 on intracellular calcium transient and its mechanisms. Neonatal rat cardiomyocytes were prepared and calcium transient was measured using fura-2. Treatment with ET-1 for 48 h prolonged calcium transient decay. In the presence of thapsigargin, ET-1 did not alter calcium transient decay. On the other hand, the prolonged calcium transient decay was maintained even when sodium was removed from the bath solution. These results indicate that ET-1-induced prolongation of calcium transient decay is mainly due to the suppression of calcium uptake by sarcoplasmic reticulum, but not inhibition of the sodium/calcium exchanger. Northern blotting analysis revealed that sarcoplasmic reticulum ATPase (SERCA2) mRNA was decreased in ET-1-treated cardiomyocytes, and that this decrease was inhibited by BQ-123 but not by BQ-788. Moreover, pretreatment with chelerythrine partially restored the ET-1-induced decrease in SERCA2 mRNA, whereas phorbol 12-myristate 13-acetate markedly reduced SERCA2 gene expression. Real-time RT-PCR analysis showed abundant ETA receptor gene expression in cardiomyocytes. ET-1 reduces SERCA2 gene expression through the ETA receptor and PKC pathway, and prolongs intracellular calcium transient decay. Specific inhibition of the ETA receptor may be a possible therapeutic strategy for improving cardiac performance.
