A, photomicrograph (left) of isolated zebrafish heart (green filter lens) reveals atrium (A), ventricle (V) and bulbous arteriosus (BA). Scale bar, 1 mm. Images of isolated cells (right) from each tissue. BA cells expressing GFP are shown under UV illumination. Scale bars, 100 μm. B, RT-PCR analysis of KATP channel subunit expression, including SUR2a and SUR2b isoforms and gapdh. C, quantification of data from B.