This is a substudy of ACTG A5142. The purpose of this substudy is to evaluate blood vessel function in HIV-infected patients taking anti-HIV drugs.

Endothelial dysfunction, assessed by measurement of brachial artery reactivity, is associated with coronary artery disease. Previous studies showed that patients taking HIV protease inhibitors (PIs) had a buildup of fatty deposits in their arteries and impaired flow-mediated vasodilation of the brachial artery, whereas endothelial function was normal in HIV-infected individuals not taking PIs. The effect of three different antiretroviral regimens on endothelial function in antiretroviral naïve HIV-infected patients will be examined in this substudy.

Patients in this substudy will have Brachial Artery Reactivity Tests (BARTs), which are painless ultrasound tests of an artery in the lower arm. Brachial artery reactivity will be measured at entry and at 4 and 24 weeks after patients are randomized to one of three open-label drug regimens in ACTG A5142. Brachial artery reactivity in response to two vasoactive stimuli (flow-mediated and nitroglycerin) will be assessed by measuring brachial artery diameter and flow velocity. Blood will be drawn at Weeks 4 and 24 for insulin and lipid tests. Patients will fast and refrain from tobacco and caffeine use for at least 8 hours prior to each study visit. For the duration of the substudy, patients will be asked not to change the amount of fruits, juices, antioxidants, and tea that they consume.

Inclusion Criteria:

• Participation in ACTG A5142 .
• Able and willing to give written informed consent and to report current smoking status.
• Men who have been on stable testosterone replacement for at least 3 months prior to entry and plan to continue to receive a stable dose during the substudy may enroll. Men who have discontinued testosterone therapy must be off for at least 3 months to be eligible.
• Women receiving oral contraceptives, hormone replacement, or progestational derivatives must have been on stable regimens for at least 3 months prior to enrollment and must plan to remain on the same dose for the duration of the study. Women who have discontinued such therapy must be off for at least 3 months to be eligible.

Exclusion Criteria:

• Coronary heart disease, peripheral vascular disease, or cerebrovascular disease.
• Diabetes mellitus, with the exception of a previous history of gestational or steroid-induced diabetes mellitus within 12 weeks prior to substudy entry.
• Insulin-sensitizing agents such as metformin, pioglitazone, and rosiglitazone.
• Lipid-lowering drugs within 6 weeks prior to substudy entry.
• Systemic glucocorticoids, long-acting inhaled steroids, and certain anabolic steroids within 30 days prior to substudy entry.
• Uncontrolled hypertension.
• Heavy use of vitamin supplements.