Hemodynamic-responsive Trpv4 modulates NO and Notch signaling during ventricle regeneration. A Trpv4 immunostaining (red) in Tg(kdrl:eGFP) larvae at 3 dpf showed ubiquitous expression of Trpv4 in the hearts. Bottom panels, enlargement of boxed areas of the bulbus arteriosus (BA) and atrioventricular canal (AVC). B Trpv4 immunostaining (intensity gradient) indicated that Trpv4 upregulation after ventricle ablation was blocked in tricaine-treated hearts at 24 and 48 hpt. C DAF-FM DA staining of Tg(vmhc:mCherry-NTR) larvae showed that Trpv4 agonist 4α-pdd treatment for 48–72 hpt partially rescued the NO signal which was suppressed by tricaine in ablated hearts. D Confocal images of Tg(vmhc:mCherry-NTR; tp1:d2GFP) hearts showed that Trpv4 agonist 4α-pdd treatment for 0–24 hpt partially rescued Notch signaling which was suppressed by tricaine in ablated hearts. E, F Quantification of the heart recovery rate in ablated groups treated with DMSO, DMSO + Tric, 4α-pdd + Tric (48–72 hpt) or 4α-pdd + Tric (0–24 hpt) at 96 hpt. The numbers of larvae analyzed for each condition are indicated. Binomial test, **P < 0.01. G NO production in ablated hearts was significantly inhibited in trpv4−/− mutants. H Notch signaling activation in ablated hearts was significantly inhibited in trpv4−/− mutants. Scale bars, 50 μm. Dashed lines outline the hearts. dpf days post fertilization, hpt hours post treatment, NO nitric oxide, Tric tricaine
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