Figure 1. Expression of selected K⁺ channel genes and α-subunits in HACs.

A,expression levels of transcripts of K⁺ channel genes in isolated HAC, determined using qRT-PCR. mRNA levels of each gene were normalized to 18S mRNA levels. Three of nine KCNK genes were expressed at readily detectable levels. KCNMA1, corresponding to large conductance Ca²⁺-activated, ‘BK’ K⁺ channel, was expressed at high levels. Genes for two inwardly rectifying K⁺ channels (KCNJ) were expressed at low or negligible levels. Data were pooled from 4 different donors. B, immunocytological evidence for expression of TASK-2 (KCNK5) and BK (KCNMA1) K⁺ channel α-subunits in isolated HACs. Cells were in culture for 1 day (TASK-2) or 2 days (BK). Three different HACs are shown for each antibody. The fluorescence image as shown in the left columns; the corresponding differential interference contrast image of each cell is shown at right. The calibration bar corresponds to 5 μm.