Heterogeneous expression of tandem-pore K+ channel genes in adult and embryonic rat heart quantified by real-time polymerase chain reaction.

1. Many members of the tandem-pore K+ channel gene family have been reported to be present in cardiac cells. However, the pattern of gene expression of these channels in the heart is a matter of some dispute. 2. Here, we used reverse transcription and real-time quantitative polymerase chain reaction to investigate the pattern of gene expression of nine members of the tandem-pore K+ channel genes in adult and embryonic rat heart. The genes (TWIK-1, TWIK-2, TASK-1, TASK-2, TASK-3, TREK-1, TREK-2, TRAAK and KCNK6) were quantified, relative to glyceraldehyde-3-phosphate dehydrogenase (GADPH), in all four chambers of adult rat hearts and in the ventricles of embryonic rat hearts. 3. All these genes were detected in at least one chamber of the heart, with a predominance of TWIK-2, TASK-1 and TREK-1 expression. The expression of TWIK-2 was higher in the right atrium than in other cardiac chambers, TASK-1 was expressed more in atria than in ventricles and TREK-1 was highly expressed in the right ventricle. 4. The expression levels of the three predominant genes in embryonic rat ventricle are much lower than their expression in adult rat ventricles. 5. The physiological implications of the differential gene expression of the tandem-pore K+ channels is discussed.