Related Experiment Video
Updated: Jun 28, 2026

Long-Term Continuous Measurement of Renal Blood Flow in Conscious Rats
Published on: February 8, 2022
Allopurinol and nitric oxide activity in the cerebral circulation of those with diabetes: a randomized trial
Jesse Dawson1, Terry Quinn, Craig Harrow
1Acute Stroke Unit, Division of Cardiovascular and Medical Sciences, University of Glasgow, Western Infirmary, Glasgow, UK. j.dawson@clinmed.gla.ac.uk
Objective:
Type 2 diabetes increases risk of stroke, perhaps because of impaired cerebrovascular basal nitric oxide (NO) activity. We investigated whether this activity is improved by a 2-week course of the xanthine oxidase inhibitor allopurinol.
Research Design And Methods:
We performed a randomized, double-blind, placebo-controlled crossover study. We measured the response to infusion of NG-monomethyl-L-arginine (l-NMMA) in males with type 2 diabetes before and after allopurinol or placebo. The primary end point was the change in internal carotid artery flow following L-NMMA infusion, expressed as the area under the flow-per-time curve.
Results:
We enrolled 14 participants. Allopurinol improved responses to L-NMMA when compared with responses associated with placebo (P = 0.032; median reduction in internal carotid artery flow following L-NMMA of 3,144 ml [95% CI 375-7,143]).
Conclusions:
Xanthine oxidase inhibition with allopurinol appears to improve cerebral NO bioavailability, as evidenced by a greater response to infusion of L-NMMA.
Related Concept Videos
Antihypertensive Drugs: Vasodilators
Antianginal Drugs: Nitrates and β-Blockers
Organic nitrates, such as nitroglycerin, play a pivotal role. Once metabolized, they liberate nitric oxide, a molecular marvel. Nitric oxide triggers guanylyl cyclase and augments cGMP production. This biochemical cascade orchestrates the relaxation of vascular smooth muscles, ushering in vasodilation and enhancing coronary blood flow. Administered...
Nitric Oxide Signaling Pathway
Treatment for Pulmonary Arterial Hypertension: Phosphodiesterase Inhibitors
Among the PDE5 inhibitors, sildenafil (Revatio) stands out as a competitive and selective inhibitor. It operates by elevating cellular levels of cGMP and augmenting signaling through the cGMP-PKG pathway, promoting vasodilation. Upon oral...
Treatment for Pulmonary Arterial Hypertension: Prostacyclin Receptor Agonists
These agonists bind to the IPR receptor situated on the plasma membrane of the pulmonary artery smooth muscle cells. This binding triggers a cascade of reactions known as the GS-AC-cAMP-PKA pathway. This pathway results in the relaxation of smooth muscle...
Antihypertensive Drugs: Direct Renin Inhibitors
