Brain natriuretic peptide secretion in adult rat heart muscle cells: The role of calcium channels

Background. - The cellular mechanisms that regulate B-type natriuretic secretion are not well elicited. Intracellular fluctuation of calcium ions rate seems to be implicated. Aims. - In this study, we evaluate the role of ventricular transmembrane calcium channels in the secretion of BNP in normal adult rats (group N) and pressure overload hypertrophied ones (group H). Methods. - We measured plasma BNP concentration and BNP concentration in culture media of cardiomyocytes from N and H group in the presence and absence of calcium channels antagonists. Results. - Plasma BNP concentration was increased in H group in comparison to N group (0.630±0.008 ng/ml versus 0.106±0.004 ng/ml; p < 0.01). This increase in BNP level was also obtained in culture media of H group in comparison to N group (3.45±0.7 ng/ml versus 0.53±0.22 ng/ml). However, the presence of calcium channels antagonists in the culture media of cardiomyocytes had decreased BNP concentration in both N (nifedipine: 0.22±0.04 ng/ml; verapamil: 0.19±0.05 ng/ml; diltiazem: 0.17±0.03 ng/ml; p < 0.05) and H group (nifedipine: 0.18±0.05 ng/ml; verapamil: 0.23±0.04 ng/ml; diltiazem: 0.28±0.1 ng/ml; p < 0.05). Conclusion. - These results suggest that transmembrane calcium channels may have an important role in the regulation of BNP secretion. © 2008 Elsevier Masson SAS. All rights reserved.