Different Effect of Felodipine and Amlodipine on Nadph Oxidase Expression and Function in Human Smooth Muscle Cells

The aims of the study were: to evaluate the anti-oxidant potential of calcium channel blockers felodipine (Fel) and amlodipine (Aml); to estimate their effect on ROS production and on NADPH oxidase (NADPHox) expression and function in human aortic smooth muscle cells (SMCs) stimulated with angiotensin II. Human SMCs were stimulated 24h with 1μM Ang II in the presence or absence of 10 μM drugs. Intracellular ROS production was detected by spectrofluorimetry using 5 μM dichlorofluoresceine (DCF). The lucigenineenhanced chemiluminiscence assay was used to determine NADPH oxidase activity. Quantification of protein and gene expression of NOX1 was done by Western blot and realtime PCR. By comparison to the control level, stimulation of SMCs with Ang II induced a significant increase of: intracellular ROS production; NADPHox activity; NOX1 mRNA expression and NOX1 protein level. Treatment with calcium channel blockers determined a significant decrease of: ROS production (Fel 80% vs. Aml 30%); NADPHox activity (Fel 50% vs. Aml 20%); NOX1 mRNA expression (Fel 50% vs. Aml20%); NOX1 proteic level (Fel 80% vs. Aml 5%). Felodipine and amlodipine have different anti-oxidant capacity. The unlike effects of the two compounds of the same class of L-type calcium channel blockers suggests distinct mechanisms of action and prefigurate a new therapeutic strategy for oxidative stress reduction in patients with arterial hypertension.