Sildenafil causes pulmonary vasodilation, thus potentially reducing impairments of hypoxia-induced pulmonary hypertension on exercise performance at altitude. The purpose of this study was to determine the effects of sildenafil during normoxic and hypoxic exercise. We hypothesized that 1) sildenafil would have no significant effects on normoxic exercise, and 2) sildenafil would improve cardiac output, arterial oxygen saturation (SaO2), and performance during hypoxic exercise. Ten trained men performed one practice and three experimental trials at sea level (SL) and simulated high altitude (HA) of 3,874 m. Each cycling test consisted of a set-work-rate portion (55% work capacity: 1 h SL, 30 min HA) followed immediately by a time trial (10 km SL, 6 km HA). Double-blinded capsules (placebo, 50, or 100 mg) were taken 1 h before exercise in a randomly counterbalanced order. For HA, subjects also began breathing hypoxic gas (12.8% oxygen) 1 h before exercise. At SL, sildenafil had no effects on any cardiovascular or performance measures. At HA, sildenafil increased stroke volume (measured by impedance cardiography), cardiac output, and SaO2 during set-work-rate exercise. Sildenafil lowered 6-km time-trial time by 15% (P<0.05). SaO2 was also higher during the time trial (P<0.05) in response to sildenafil, despite higher work rates. Post hoc analyses revealed two subject groups, sildenafil responders and nonresponders, who improved time-trial performance by 39% (P<0.05) and 1.0%, respectively. No dose-response effects were observed. During cycling exercise in acute hypoxia, sildenafil can greatly improve cardiovascular function, SaO2, and performance for certain individuals.

Background Antiretroviral treatment (ART) initiatives have now been established in many sub-Saharan African countries showing early benefits. To date, few results are available concerning long-term clinical outcomes in these treatment programs. Methods Response to ART is described in the first HIV–1C infected adults enrolled in the Botswana ART program in 2002. Data analysis was conducted on available longitudinal data up to April 1st, 2007. Results 633 severely immunodeficient patients with a median CD4+ cell count of 67 cells/mm3 were initiated on NNRTI-based combination ART and followed for a median of 41.9 months. The median CD4+ increases were 169 cells/mm3, 302 cells/mm3, and 337 cells/mm3 at 1, 3, and 5 years, respectively. The percentages of patients with a viral load of less than 400 copies/mL at 1, 3, and 5 years were 91.3%, 90.1%, and 98.3%, respectively. 75% of patients did not miss a single, or missed only one, monthly ART pick-up per year with a mean pick-up rate of 92.5%. The Kaplan-Meier survival estimates (95% CI) at 1, 3, and 5 years were 82.7% (81.2%, 84.3%), 79.3% (77.6%, 81.0%), and 79.0% (77.3%, 80.7%), respectively. At six months, the risk of treatment modification for anemia was 6.94% (5.9%, 8.0%) for cutaneous hypersensitivity reactions, 1.3% (0.8%, 1.7%), and 1.1% (0.7%, 1.6%) for hepatotoxicity. Conclusions This initial group of adults on ART in Botswana had excellent sustained immunologic, virologic, and clinical outcomes for up to five years of follow-up with low mortality among those surviving into the second year of antiretroviral treatment.

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