['Our objective was to characterize the local vascular effects of gastrin-releasing peptide in forearm resistance vessels as a biomarker to aid the clinical development of broad-spectrum neuropeptide antagonists as anticancer agents.', 'On different occasions, 7 healthy male volunteers received brachial artery infusions of gastrin-releasing peptide, and forearm blood flow was measured by venous occlusion plethysmography. Dose-finding studies identified a range of pharmacologically active doses of gastrin-releasing peptide (3 to 450 pmol/min) for use in dose response and tachyphylaxis studies. The nitric oxide clamp method was used for the assessment of the contribution of nitric oxide to the vasodilatory effect shown.'] Is gastrin-releasing peptide a potent vasodilator in humans?