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

Abstract

BACKGROUND:

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.

METHODS AND RESULTS:

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.

CONCLUSIONS:

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.

• Authors: A Hempel, C Lindschau, C Maasch, M Mahn, R Bychkov, T Noll, F C Luft, H Haller
• Journal: Circulation (Circulation) Vol. 99 Issue 19 Pg. 2523-9 (May 18 1999) ISSN: 0009-7322 [Print] United States
• PMID: 10330383 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Calcium Channel Blockers
• Poisons
• Protein Kinase C
• Nifedipine
• Potassium Cyanide

Topics

• Animals
• Calcium Channel Blockers (pharmacology)
• Capillary Permeability (drug effects)
• Cells, Cultured
• Endothelium, Vascular (drug effects, metabolism, pathology)
• Ischemia
• Nifedipine (pharmacology)
• Poisons (toxicity)
• Potassium Cyanide (toxicity)
• Protein Kinase C (antagonists & inhibitors)
• Swine