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.
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.