title: Effects of antisense oligonucleotides to the cardiac Na+/Ca2+ exchanger on calcium dynamics in cultured cardiac myocytes.
abstract: The present study was designed to explore the role of the Na+/Ca2+ exchanger on spontaneous beating of cultured cardiac myocytes. Antisense oligonucleotides (AS) based on the sequence of the cardiac Na+/Ca2+ exchanger were used to decrease expression of this Ca2+ transporting protein in cardiac myocytes. An application of AS (10 microM) caused an increase in beating rate of myocytes within 6-24 h. After 24 h of exposure, AS increased the beating rate from an average rate of 77 beats/min in control and sense-treated myocytes to 103 beats/min. Moreover, myocytes treated for 24 h with 10 microM AS exhibited an increase in diastolic [Ca2+]i levels. The antisense treatment also led to a approximately 20% decrease in expression of Na+/Ca2+ exchanger proteins within 6-24 h. Changes in mRNA levels following AS treatment could not be detected within 3- to 24-h periods. The results of these studies suggest that the Na+/Ca2+ exchanger plays a potentiating role in spontaneous the beating process by regulating [Ca2+]i dynamics and that even a small reduction in the levels of the exchanger protein has marked effects on the handling of [Ca2+]i during the cardiac cycle.
authors.affiliation: Department of Clinical Evaluation of Medicines and Therapeutics, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Suita, 565-0871, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Azuma
authors.forename: J
authors.initials: J
authors.lastname: Huschenbett
authors.forename: M L
authors.initials: ML
authors.lastname: Michaelis
authors.forename: J
authors.initials: J
authors.lastname: Azuma
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D006321:Heart / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D012333:RNA, Messenger / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
chemical_list: D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D002118:Calcium