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Fig. 3
Manipulation of cardiac natriuretic peptide expression alters total cardiomyocyte numbers in the embryonic heart. (A) Total cardiomyocytes at 48 hpf were increased in the Nppa/Nppb double knockdown (nppa/nppb MO) embryos, but were decreased in the nppb overexpression embryos (HS/nppb). *P<0.02 compared with control. (B) Representative images from cmlc2:CFP (pseudo-colored green) and DAPI (pseudo-colored red) stained hearts. (C) The total number of apoptotic heart cells was not increased in the nppb overexpression embryos. P>0.05 compared with control. (D) Knockdown of Nppa/Nppb and overexpression of nppb were able to significantly alter cardiomyocyte proliferation at 52 hpf. *P<0.03 compared with control. (E) Representative images of BrdU-labeled (red) cmlc2:CFP (green)-positive heart tissue. White arrowhead indicates BrdU-positive cardiomyocytes. Intracavitary BrdU+ cells were considered to be endothelial in origin and were not counted. All data are expressed as mean + s.e.m. Scale bars: 100 μm.