Egger, Marcel Porzig, Hartmut Niggli, Ernst Schwaller, Beat 2005-01-12 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 “<i>functional half-life</i>” of the NCX1 protein in the plasma membrane of neonatal cardiac myocytes is surprisingly short, much shorter than reported <i>half-lifes</i> of about 30 h for other membrane proteins. application/pdf https://folia.unifr.ch/global/documents/299805 https://folia.unifr.ch/documents/299805/files/1_schwaller_rtf.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.ceca.2004.10.006 info:eu-repo/semantics/openAccess License undefined Cell Calcium. - 2005, vol. 37, no. 3, p. 233-243 sodium–calcium exchange NCX antisense oligodeoxynucleotides cardiac myocyte heart intracellular calcium calcium transport caged calcium sf9 cells info:eu-repo/classification/udc/57 Rapid turnover of the “functional” Na⁺–Ca²⁺ exchanger in cardiac myocytes revealed by an antisense oligodeoxynucleotide approach http://purl.org/coar/resource_type/c_6501