Specific inhibition of Na-Ca exchange function by antisense oligodeoxynucleotides.
The Na-Ca exchanger is essential for the Ca2+ homeostasis in many cell types. This transporter has been difficult to investigate because no specific inhibitor is available. We have synthesized an antisense oligodeoxynucleotide directed against the rat cardiac Na-Ca exchanger mRNA. To estimate the activity of the Na-Ca exchange in single cultured myocytes, the exchange current (INaCa) was measured with the voltage-clamp technique while the intracellular Ca2+ concentration ([Ca2+]i) was simultaneously recorded. Most cells exposed to antisense oligodeoxynucleotide showed neither an INaCa nor an increase of [Ca2+]i upon extracellular Na+ removal. Liberation of Ca2+ by flashphotolysis of caged Ca2+ was not followed by a decay of [Ca2+]i in cells exposed to the antisense oligonucleotide, whereas in control cells resting [Ca2+]i was reached 6 s after the flash. Control experiments with non-sense and mismatched oligonucleotides were performed to exclude unspecific inhibitory effects. These results demonstrate that the Na-Ca exchange was specifically and completely suppressed and that antisense oligodeoxynucleotides represent a useful tool to investigate the cellular and molecular properties of the Na-Ca exchanger.
Lipp
P
P
Department of Physiology, University of Bern, Switzerland.
Schwaller
B
B
Niggli
E
E
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D002478:Cells, Cultured; D004285:Dogs; D006801:Humans; D017136:Ion Transport / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology*; D010782:Photolysis; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger
D002352:Carrier Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D012964:Sodium; D002118:Calcium