Rapid-onset endothelial dysfunction with adriamycin: evidence for a dysfunctional nitric oxide synthase

Adriamycin (ADR) is a commonly used chemotherapeutic agent that is believed to exert its effects through the generation of oxygen free radicals. We hypothesized that administration of a single dose of ADR results in endothelial nitric oxide synthase (eNOS)-dependent generation of superoxide (O2·-) and acute endothelial dysfunction. A single dose of ADR (10 mg/kg i.v.) administered to rabbits resulted in rapid attenuation of agonist-dependent responses to acetylcholine and calcium ionophore (A23187). In vitro exposure of ring segments to ADR for 2·- generation measured by electron spin resonance (ESR) with the spin trap segments 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide (BMPO) that was abolished by endothelial denudation and incubation with diphenyliodonium (DPI) (10 mM) but not L-NMMA (10 mM). Brachial artery flow-mediated dilation (FMD) in patients undergoing chemotherapy with ADR was markedly attenuated after a single dose of ADR (6.5 6 1.0 to 2.5 6 1.1% (p = 0.0004, time to end of infusion 27 6 8 min) while endothelial-independent dilatation with nitroglycerin was unchanged (16.3 6 3.1 and 14.33 6 2.1% respectively, p = 0.36). Serum nitrite and nitrate concentrations fell from 50 6 6 mmol/l pre-ADR to 33 6 6 mmol/l post-ADR infusion (p = 0.0005) while serum concentrations of CD141 thrombomodulin and von Wille-brand factor (vWF) activity remained unchanged after ADR infusion (36 6 13 to 52 6 22% ng/ml versus 3.25 6 0.98 to 3.01 6 0.91%, respectively, p = NS for pre versus post for both). Doppler indices of diastolic function (IVRT, DT and E/A ratios) were not altered in response to ADR. In conclusion, ADR administration results in rapid depletion of systemic NO· levels and attenuation of agonist-dependent responses in rabbits and flow-mediated dilation in the brachial artery of humans. ESR measurements in rabbit ring suggest an endothelial origin for radical production via flavin-containing oxido-reductases such as eNOS or NADPH cytochrome P450 reductase. These fi ndings may have implications for cardiovascular complications noted with ADR.