Inhibition of NAD(P)H oxidase attenuates aggregation of platelets from high-risk cardiac patients with aspirin resistance.
Up to one-third of serious vascular events in high-risk patients is attributable to a failure of aspirin (ASA) to suppress platelet aggregation. We hypothesized that inhibition of NAD(P)H oxidase may inhibit aggregation of platelets from ASA-resistant (ASA-R) patients. Thus, platelet-rich plasma was isolated from ASA-sensitive (ASA-S) and ASA-R patients (aspirin resistance was defined as higher than expected aggregation to collagen and epinephrine [> or = 40%] after chronic oral treatment with 100 mg/day ASA). Aggregation to adenosine diphosphate (ADP) (5 and 10 micromol/l), collagen (2 microg/ml) and epinephrine (10 micromol/l) in the absence and presence of the NAD(P)H oxidase inhibitors: diphenylene iodonium (DPI) (1 micromol/l) and apocynin (3 x 10(-4) mol/l) was measured by optical aggregometry. Maximal aggregation of ASA-R platelets to collagen and epinephrine was significantly decreased by DPI and apocynin, whereas they had no effect in ASA-S platelets. Maximal aggregation to ADP was unaffected by NAD(P)H oxidase inhibition in either group. In ASA-R platelets both NADPH-driven O2(.-) production (lucigenin chemiluminescence assay) and expression of gp91phox and p67phox subunits of the NADPH oxidase (Western blotting) tended to increase. Collectively, inhibition of NAD(P)H oxidase effectively suppressed collagen and epinephrine-induced aggregation of platelets from ASA-R patients, which may represent a novel pharmacological target for cardioprotection in high-risk cardiac patients.
Stef
Gyorgyi
G
State Hospital for Cardiology, Balatonfured 8230, Hungary.
Csiszar
Anna
A
Ziangmin
Zhao
Z
Ferdinandy
Peter
P
Ungvari
Zoltan
Z
Veress
Gabor
G
D000098:Acetophenones / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000284:Administration, Oral; D000368:Aged; D001241:Aspirin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D015153:Blotting, Western; D003094:Collagen / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006331:Heart Diseases / Q000097:blood* / Q000201:enzymology; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects*; D010979:Platelet Function Tests / Q000379:methods; D053657:Platelet-Rich Plasma / Q000187:drug effects / Q000378:metabolism
D000098:Acetophenones; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D009861:Onium Compounds; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D000244:Adenosine Diphosphate; C007517:diphenyleneiodonium; D003094:Collagen; C056165:acetovanillone; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D001241:Aspirin