Figure 5. BNP binds to NPR-B to stimulate Sca-1^high+ cell proliferation.

(A) Non-myocyte cells (NMCs) isolated from the hearts of neonatal NPR-A or NPR-B deficient mice were cultured with and without BNP. The total number of cells, the percentages of Sca-1⁺ cells obtained by flow cytometry analysis as well as the number of Sca-1⁺ cells were determined 11 days after the onset of BNP treatment. n = 9 different experiments for NPR-A and NPR-B deficient cells. (B and D) Sorted Sca-1^high+ cells isolated from wild type hearts were cultured with BNP or CNP in presence or not of NPR-B receptor antagonist (P19, 0.5–1 microM) and of an ANF antagonist (Anantin, 0.2 microM). The number of cells was counted after 9–11 days of culture and the results were related to untreated cells. n = at least 4 different experiments. (C) NMCs isolated from wild type hearts were treated with C-natriuretic peptide (CNP) for up to 11 days. The total number of cells as well as the number of c-kit⁺ and Sca-1⁺ cells were determined after counting and flow cytometry analysis. n = 6 different experiments (D). (A–D) Results expressed as fold-increase above the results in the related untreated cells. All the results are means ± SEM. *p < 0.05 versus the related untreated cells, ^°p < 0.05 versus the untreated cells without inhibitors, ^§p < 0.05 versus the BNP treated cells without inhibitors.