Renal Oxygen Content is Increased in Healthy Subjects After Angiotensin Converting Enzyme Inhibition

Subjects The study will be conducted under a protocol (number 4111/08) approved by the Ethics Committee of the Instituto de Cardiologia do Rio Grande do Sul-Fundação Universitária de Cardiologia/Brazil. After giving their informed consent,the patients will participate in the study. None of the subjects will take medication,food and water overnight. All measurements will be performed at the end of the morning.

After control BOLD-MRI measurements acquisition, subjects will take an oral ACE inhibitor (captopril 25 mg). Thirty minutes after captopril administration, without moving from the scanner, blood pressure will be measured and a second BOLD acquisition will be performed to detect a possible alteration in the renal oxygenation. Data will be collected by two radiologists and interpreted by a physician and a physiologist.

MR Imaging Technique Images were acquired using 1.5T HDx (Sigma, GE Healthcare, Waukesha, Win) and an 8 channels body coil.

Localizer images will be performed with axial and sagittal planes following the long axis of both kidneys, using breath hold and fast spoiled gradient echo (FSPGR) technique.

Oblique axial and coronal reference images will be acquired for color maps following approximately the short and long axis of both kidneys using FSPGR with the following parameters: FOV=40cm, matrix 256x128, slice thickness=5cm, slice gap 6cm, 3 slices per plane in one breath hold. TR=150ms, TE=min full, FLIP=90, rBW=62KHz, 1NEX. This sequence provides an excellent contrast between cortex and medulla and avoid the unnecessary use of a contrast agents.