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. [Ca 2ϩ ] 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 [Ca 2ϩ ] 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-␣ and PKC-. Specific inhibition of PKC isoforms with antisense oligodeoxynucleotides demonstrated a major role for PKC-␣. 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-␣ inhibition. Anti-ischemic effects of dihydropyridine calcium antagonists could be due in part to their effects on endothelial cell permeability. (Circulation. 1999;99:2523-2529.)

Amlodipine Modulates THP-1 Cell Adhesion to Vascular Endothelium via Inhibition of Protein Kinase C Signal Transduction

“…27 We observed an effect of amlodipine on PKC isoforms ␣ and ␤, but not ␦ or . The importance of PKC-␣ and -␤ during cell adhesion has been previously reported, 27,28 as Sun et al 28 showed that overexpression of PKC-␣ enhanced the motility and adhesion of breast cancer cells and Nonaka et al 29 found that inhibition of PKC-␤ resulted in reduced entrapment of leukocytes in rat diabetic retina models.…”

“…One possible explanation is that amlodipine interferes with the release of phospholipid components, such as diacylglycerol, from the plasma membrane to activate PKC. 27 As previously reported, disturbance of this phospholipid would dramatically affect PKC signaling. 30 Furthermore, the unique characteristics of amlodipine that cause it to exhibit a strong and sustained affinity to the lipid bilayer might play a role in the amlodipine-dependent reduction of THP-1 cell adhesion.…”

In vivo myocardial gene transfer: optimization and evaluation of intracoronary gene delivery in vivo

“…Consequently myocardial ischaemia was easily induced, and likely to have been repetitive. Circumstances that are known to increase endothelial permeability, 15 possibly explaining the relatively high transfection efficiency. The relevance of the study by Giordano et al 14 to patients with ischaemic heart disease was immediately obvious.…”

Reactive Oxygen Species in Inflammation and Tissue Injury

“…These studies support a prominent role of different PKC isoforms in microvascular leakage associated with different pro-inflammatory mediators. Increased PKC activity has also been associated with various vascular disorders such as atherosclerosis, hypoxia, and ischemia reperfusion (138,174,286,447).…”