Brain natriuretic peptide (BNP) gene expression in the heart of vasopressin-deficient Brattleboro rats.

Brain natriuretic peptide (BNP) messenger RNA was measured with a semiquantitative method from heart auricles and ventricles of vasopressin-deficient Brattleboro rats (DI) and from desmopressin treated Brattleboro rats (DI + DDAVP). Desmopressin had been injected peripherally and Long-Evans rats (LE) served as controls. The 3-day substitution treatment had shifted the fluid balance of DI almost to that of LE. In the present study, the amount of BNP mRNA, normalized to the glyceraldehyde-3-phosphate dehydrogenase mRNA content, was constant in all three groups in the right auricle. No changes were when the right auricular and left auricular mRNA levels were compared within each group. In the left auricle, desmopressin treatment increased significantly (P < 0.05) the amount of BNP mRNA compared with that of LE rats (from 1.09 +/- 0.21, n = 7 to 1.72 +/- 0.17, n = 8, arbitrary units). In all groups, the left ventricle had significantly (P < 0.05) higher mRNA content than the right ventricle (LE: 2.24 +/- 0.23 vs. 0.67 +/- 0.13, n = 6; DI: 2.30 +/- 0.60 vs. 0.33 +/- 0.05, n = 8; DI + DDAVP: 2.36 +/- 0.29 vs. 0.37 +/- 0.07, n = 10). In the right ventricle, both DI and DI + DDAVP rats had significantly (P < 0.05) lower mRNA content than LE rats (0.33 +/- 0.5 vs. 0.67 +/- 0.13 and 0.37 +/- 0.07 vs. 0.67 +/- 0.13, respectively). To conclude, these findings suggest that brain natriuretic peptide gene expression dissociates from, or rapidly adapts to, the chronic effects of peripheral desmopressin treatment which have shifted the fluid balance to almost normal in Brattleboro rats. The left ventricular pressure appears to regulate the brain natriuretic peptide gene expression.