[1] Duke Univ, Med Ctr, Dept Med, Durham, NC 27710 USA
[2] Duke Univ, Med Ctr, Div Cardiol, Durham, NC 27710 USA
[3] Duke Clin Res Inst, POB 17969, Durham, NC 27715 USA
[4] Duke Univ, Med Ctr, Div Pharmacol, Durham, NC USA
[5] Univ Gothenburg, Sahlgrenska Acad, Gothenburg, Sweden
[6] Imperial Coll London, Natl Heart & Lung Inst, London, England