no evidence of underlying cardiac disease based on history or electrocardiogram (ecg)

adequate intravenous access in one arm

pregnant or breastfeeding; if pre-menopausal, not practicing acceptable method of birth control

history of any other medical condition that is likely to hinder study conduct or pose a safety concern, in the opinion of the investigator

history of cardiac disease, including heart attack or heart valve disease

uncontrolled high blood pressure, defined as systolic blood pressure higher than 160 mm hg and/or diastolic pressure higher than 100 mm hg

abnormal ecg or chest pain syndrome

claustrophobia

resting heart rate greater than 110 bpm

unable to undergo mri procedure (e.g., pacemaker, metallic implants)