The Nitrite and Coronary Flow Study

This is a healthy volunteer, proof of concept study. The participant will have blood taken and this will be analysed for baseline levels of nitrate, nitrite and nitroso species. They will then have a baseline MRI to assess coronary flow in normoxia. Next, hypoxia will be induced using 12% oxygen/88% nitrogen. The participant will then have a baseline MRI to assess coronary flow in hypoxia (3 breath-hold image captures). After all baseline images have been captured, the investigators will commence an intravenous nitrite sodium infusion, dose 70μmol, of 5 minute duration (14μmol /min-1). At the 5th minute, the participant have a further MRI image to assess coronary flow with the intervention in normoxia (3 breath-hold image captures). A 10-minute washout will follow (with the half-life of nitrite being documented as 110 seconds). There will be optional repeat 3 breath-hold image captures at 5 minutes and at 10 minutes. Next hypoxia will be induced using 12% oxygen/88% nitrogen again. The investigators will commence a second intravenous nitrite sodium infusion, dose 70μmol, 5 minute duration (14μmol /min-1). At the 5th minute, the participant will have a further MRI image to assess coronary flow with the intervention in hypoxia (3 breath-hold image captures). At the end of the study the participant will have blood taken and this will be analysed for repeat levels of nitrate, nitrite and nitroso species. All interventions will be performed by fully trained and competent medical staff.