Related Experiment Video
Updated: Aug 19, 2026
Analysis of Cardiac Contractile Dysfunction and Ca2+ Transients in Rodent Myocytes
Published on: May 25, 2022
Rapid turnover of the "functional" Na(+)-Ca2+ exchanger in cardiac myocytes revealed by an antisense
Marcel Egger1, Hartmut Porzig, Ernst Niggli
1University of Bern, Department of Physiology, Bühlplatz 5, CH-3012 Bern, Switzerland. egger@pyl.unibe.ch
Abstract:
Antisense oligodeoxynucleotides (AS-ODNs) were used in combination with transient functional expression of the cardiac Na(+)-Ca2+ exchanger (NCX1) to correlate suppression of the Na(+)-Ca2+ exchange function with down-regulation of NCX1 protein expression. In a de-novo expression system (Sf9 cells), a decrease in both, NCX1 mRNA and protein after AS-ODN application was paralleled by diminished NCX1 activity, a typical hallmark of a true "antisense effect". Although AS-ODN uptake was also efficient in rat neonatal cardiac myocytes, in whole-cell extracts of these cells treated with AS-ODNs, the amount of NCX1 protein determined in a quantitative binding assay remained almost unchanged, despite a prompt loss of NCX1 function. Immunocytochemical staining of myocytes revealed that most of the immunoreactivity was not localized in the plasma membrane, but in intracellular compartments and was barely affected by AS-ODN treatment. These results indicate that the "functional half-life" of the NCX1 protein in the plasma membrane of neonatal cardiac myocytes is surprisingly short, much shorter than reported half-lifes of about 30 h for other membrane proteins.
Insights
Antisense oligodeoxynucleotides (AS-ODNs) effectively reduced cardiac Na(+)-Ca2+ exchanger (NCX1) function in myocytes. However, NCX1 protein levels remained unchanged, suggesting rapid protein turnover rather than degradation.
Area of Science:
- Molecular biology
- Cardiovascular physiology
- Biochemistry
Background:
- The cardiac Na(+)-Ca2+ exchanger (NCX1) plays a crucial role in regulating intracellular calcium levels in cardiomyocytes.
- Understanding the regulation of NCX1 expression and function is vital for comprehending cardiac contractility and potential therapeutic interventions.
Purpose of the Study:
- To investigate the correlation between antisense oligodeoxynucleotide (AS-ODN)-mediated suppression of NCX1 function and NCX1 protein expression.
- To determine the efficacy of AS-ODNs in down-regulating NCX1 in a de-novo expression system and in primary cardiac myocytes.
- To elucidate the mechanism underlying the loss of NCX1 function in neonatal cardiac myocytes.
Main Methods:
- Transient functional expression of NCX1 in Sf9 cells.
- Application of AS-ODNs to Sf9 cells and rat neonatal cardiac myocytes.
- Quantitative assessment of NCX1 mRNA and protein levels using binding assays.
- Measurement of NCX1 activity.
- Immunocytochemical staining to determine NCX1 localization.
Main Results:
- AS-ODN application led to decreased NCX1 mRNA, protein, and activity in Sf9 cells, confirming a true antisense effect.
- In rat neonatal cardiac myocytes, AS-ODNs efficiently reduced NCX1 function but did not significantly alter total NCX1 protein levels.
- Immunocytochemistry revealed NCX1 predominantly in intracellular compartments, with minimal changes after AS-ODN treatment.
- The functional half-life of plasma membrane NCX1 in neonatal cardiac myocytes was found to be significantly shorter than previously reported for other membrane proteins.
Conclusions:
- AS-ODNs can effectively inhibit NCX1 function in cardiac myocytes, but this is not mediated by a reduction in total cellular NCX1 protein.
- The rapid loss of NCX1 function in neonatal cardiac myocytes suggests a very short functional half-life of the protein at the plasma membrane.
- These findings highlight the dynamic regulation of NCX1 at the post-translational level and its rapid turnover in the cardiomyocyte plasma membrane.
More Related Videos
07:38Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane
Published on: March 30, 2015
05:15Viral Transgene Expression in Rodent Hearts and the Assessment of Cardiac Arrhythmia Risk
Published on: July 27, 2022