Calcium antagonists ameliorate ischemia-induced endothelial cell permeability by inhibiting protein kinase C

• Published in: Circulation (New York, N.Y.) N.Y.), 1999-05, Vol.99 (19), p.2523-2529
• Main Authors: HEMPEL, A, LINDSCHAU, C, MAASCH, C, MAHN, M, BYCHKOV, R, NOLL, T, LUFT, F. C, HALLER, H
• Format: Article
• Language: English
• Subjects: Animals; Antianginal agents. Coronary vasodilator agents; Biological and medical sciences; Calcium Channel Blockers - pharmacology; Capillary Permeability - drug effects; Cardiovascular system; Cells, Cultured; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Endothelium, Vascular - pathology; Ischemia; Medical sciences; Nifedipine - pharmacology; Pharmacology. Drug treatments; Poisons - toxicity; Potassium Cyanide - toxicity; Protein Kinase C - antagonists & inhibitors; Swine
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.cir.99.19.2523

Dihydropyridines block calcium channels; however, they also influence endothelial cells, which do not express calcium channels. We tested the hypothesis that nifedipine can prevent ischemia-induced endothelial permeability increases by inhibiting protein kinase C (PKC) in cultured porcine endothelial cells. Ischemia was induced by potassium cyanide/deoxyglucose, and permeability was measured by albumin flux. Ion channels were characterized by patch clamp. [Ca2+]i was measured by fura 2. PKC activity was measured by substrate phosphorylation after cell fractionation. PKC isoforms were assessed by Western blot and confocal microscopy. Nifedipine prevented the ischemia-induced increase in permeability in a dose-dependent manner. Ischemia increased [Ca2+]i, which was not affected by nifedipine. Instead, ischemia-induced PKC translocation was prevented by nifedipine. Phorbol ester also increased endothelial cell permeability, which was dose dependently inhibited by nifedipine. The effects of non-calcium-channel-binding dihydropyridine derivatives were similar. Analysis of the PKC isoforms showed that nifedipine prevented ischemia-induced translocation of PKC-alpha and PKC-zeta. Specific inhibition of PKC isoforms with antisense oligodeoxynucleotides demonstrated a major role for PKC-alpha. Nifedipine exerts a direct effect on endothelial cell permeability that is independent of calcium channels. The inhibition of ischemia-induced permeability by nifedipine seems to be mediated primarily by PKC-alpha inhibition. Anti-ischemic effects of dihydropyridine calcium antagonists could be due in part to their effects on endothelial cell permeability.