Antioxidant and Nitric Oxide-Sparing Actions of Dihydropyridines and ACE Inhibitors Differ in Human Endothelial Cells

Abstract

The effects of dihydropyridine Ca²⁺ channel blockers (DHP) and ACE inhibitors on superoxide formation and nitric oxide (NO) bioavailability were compared in human EA.Hy926 endothelial cells (EC). EC were stimulated 4 h with angiotensin II (Ang II, 10 nM) ± study drugs. Specific superoxide formation was measured by lucigenin-enhanced chemiluminescence, reduction of cytochrome c and rhodamine-123 fluorescence. Free NO release was determined with an amperometric NO sensor. NADPH oxidase subunits expression was examined with Western Blot. In untreated EC the intracellular superoxide is –64.3 ± 6.0% decreased compared to Ang II stimulated EC. Elevated extracellular superoxide formation was on a –43.0 ± 1.7% lower level in untreated EC. The DHP Ca²⁺-channel agonist BayK8644 and ACE inhibitors captopril and ramiprilat led extracellular superoxide concentration to control level. Enalaprilat blocked extracellular superoxide, the DHP amlodipine and nisoldipine prevented intracellular increases only (n = 8–9, p < 0.05). Icatibant (HOE 140), a kinin-B₂ receptor antagonist, attenuated antioxidant actions of all tested agents except of nisoldipine. Ang II-induced superoxide was elevated by the phorbolester PMA and blocked by the protein kinase C (PKC) inhibitor chelerythrine. Suppression of substance P-evoked NO release by Ang II (>70%, n = 6) was reversed by the PKC inhibitor chelerythrine, the DHP amlodipine and nisoldipine and the ACE inhibitor ramiprilat. Further, Ang II reduces Nox-4 expression by 34.5 ± 4.9. Nox-2 expression was not regulated. DHP and ACE inhibitors exert different antioxidant effects in human EC stimulated with Ang II, but both improve NO bioavailability via bradykinin and modulation of redox-regulating enzymes.

Treating hypertension while protecting the vulnerable islet in the cardiometabolic syndrome

“…This improvement may result from vasodilatory action in insulin-sensitive tissues without SNS stimulation [118], prevention of the inhibition of glucose transporters and glycogen synthase by calcium [7], or various antioxidant effects [7,119]. Antioxidant effects include inhibition of Ang II-and aldosteroneinduced superoxide formation [120,121], improvement in NO bioavailability [120,121], and reduction of oxidative stress [122,123]. CCBs have minimal effects on lipid levels [117,118,124,125].…”

“…They may improve lipid levels by improving carbohydrate metabolism [125]. Their antioxidant effects include suppression of Ang II-induced superoxide formation [120,121] and reduction in oxidative stress [148,149]. ACE inhibitors have several pancreatic benefits.…”

Calcium-Dependent NOX5 Nicotinamide Adenine Dinucleotide Phosphate Oxidase Contributes to Vascular Oxidative Stress in Human Coronary Artery Disease

“…Thus the potential role of calcium-dependent reactive oxygen species (ROS) production in human coronary artery disease remains unknown. Interestingly, it has been reported that calcium channel antagonists reduce ROS production in human endothelial cells (8). These drugs have been demonstrated to be clinically beneficial in improving clinical outcomes in patients with vascular diseases, particularly coronary artery disease.…”

Improving vascular function in hypertension: potential benefits of combination therapy with amlodipine and renin–angiotensin–aldosterone system blockers

“…Amlodipine facilitates NO release, possibly via upregulation of the endothelial isoform of NOS (i.e., eNOS). The findings from several preclinical studies [25][26][27][28][29] are consistent with such a mechanism.…”

“…Second, ACE inhibition may reduce angiotensin II-associated production of smooth muscle cell oxygen radicals that inactivate endothelial nitric oxide [45]. In human endothelial cells, the ACE inhibitors captopril and ramiprilat (but not enalaprilat) reduced angiotensin II-stimulated intracellular ROS [28]. In a separate study [29], also conducted in human endothelial cells, both captopril and enalaprilat again inhibited intracellular superoxide formation; however, captopril additionally inhibited superoxide formation extracellularly.…”