ABSTRACT
The prophylactic anti-anginal agent, perhexiline, may also be effective in acute coronary syndromes and advanced aortic valvular stenosis, conditions associated with enhanced inflammation. Its potential effects on superoxide formation via NADPH oxidase were measured by lucigenin-mediated chemiluminescence. Perhexiline inhibited superoxide formation in intact neutrophils stimulated with formyl Met Leu Phe (fMLP) 4 muM or with phorbol myristate acetate (PMA) 162 nM - IC50 2.3 microM (1.5-3.6), n=4. Sub-unit assembly of NADPH oxidase by PMA was unaffected by pretreatment with perhexiline 2 microM, a concentration which reduced superoxide formation by 44+/-5% (n=4) in intact neutrophils. Perhexiline inhibited preassembled neutrophil NADPH oxidase and that in membranes of pig valve interstitial cells, human umbilical vein endothelial cells (HUVECs) and cardiac fibroblasts, but not that in rat aorta (rings or membrane preparations). These data imply that perhexiline inhibits the phagocytic NADPH oxidase directly, and that pig aortic valvular interstitial cells possess a similar enzyme, a conclusion supported by immunohistochemical localisation of the gp91phox subunit in these cells. However further study is required to clarify the effect of perhexiline on different NADPH oxidase isoforms particularly in the vasculature.
Subject(s)
Aorta, Thoracic/drug effects , Aortic Valve/drug effects , Neutrophils/drug effects , Perhexiline/pharmacology , Superoxides/metabolism , Angina Pectoris/prevention & control , Animals , Animals, Newborn , Aorta, Thoracic/metabolism , Aortic Valve/metabolism , Cardiovascular Agents/pharmacology , Cell Membrane/drug effects , Cell Membrane/metabolism , Cells, Cultured , Dose-Response Relationship, Drug , Enzyme Inhibitors/pharmacology , Female , Free Radical Scavengers/pharmacology , Humans , In Vitro Techniques , Luminescent Measurements , Male , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , NADP/pharmacology , NADPH Oxidases/metabolism , Neutrophils/metabolism , Rats , Rats, Wistar , Superoxides/chemistry , Swine , Tetradecanoylphorbol Acetate/pharmacologyABSTRACT
The antianginal agent perhexiline inhibits rat cardiac carnitine palmitoyltransferase-1 (CPT-1) and CPT-2, key enzymes for mitochondrial transport of long-chain fatty acids. We tested the hypothesis that perhexiline, in therapeutic concentrations (2 microM), inhibits palmitate oxidation and enhances glucose oxidation in isolated rat cardiomyocytes and in the working rat heart, thereby increasing efficiency of oxygen utilization. In isolated cardiomyocytes, perhexiline (2 microM) exerted no acute effects on palmitate oxidation, but after 48 hours pre-exposure oxidation was inhibited by perhexiline (2 to 10 microM) by 15% to 35% (P < 0.0002). In non-ischemic working rat hearts (3%BSA, 0.4 mM palmitate, 11 mM glucose, 100 microU/mL insulin) perhexiline (2 microM) had no significant acute effect on cardiac efficiency, palmitate or glucose oxidation, but 24 hours pretreatment with transdermal perhexiline increased cardiac work (by 29%, P < 0.05) and cardiac efficiency (by 30%, P < 0.02) without significant effects on palmitate oxidation. The selective CPT-1 inhibitor oxfenicine (2 mM) inhibited palmitate oxidation and enhanced glucose oxidation, but failed to enhance cardiac efficiency. In conclusion, in the non-ischemic working rat heart, perhexiline increases myocardial efficiency by a mechanism(s) that is largely or entirely independent of its effects on CPT. Effects on cardiac efficiency during ischemia, and with changes in fatty acid oxidation after longer perhexiline pretreatment remain to be determined.