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Tetrahydrobiopterin augments endothelium‐dependent dilatation in sedentary but not in habitually exercising older adults
Author(s) -
Eskurza Iratxe,
Myerburgh Laura A.,
Kahn Zachary D.,
Seals Douglas R.
Publication year - 2005
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2005.092734
Subject(s) - ageing , medicine , brachial artery , endothelium , placebo , tetrahydrobiopterin , cardiology , endocrinology , nitric oxide , blood pressure , nitric oxide synthase , pathology , alternative medicine
Endothelium‐dependent dilatation (EDD) is impaired with ageing in sedentary, but not in regularly exercising adults. We tested the hypotheses that differences in tetrahydrobiopterin (BH 4 ) bioactivity are key mechanisms explaining the impairment in EDD with sedentary ageing, and the maintenance of EDD with ageing in regularly exercising adults. Brachial artery flow‐mediated dilatation (FMD), normalized for local shear stress, was measured after acute oral placebo or BH 4 in young sedentary (YS) ( n = 10; 22 ± 1 years, mean ± s.e.m. ), older sedentary (OS) ( n = 9; 62 ± 2), and older habitually aerobically trained (OT) ( n = 12; 66 ± 1) healthy men. At baseline, FMD was ∼50% lower in OS versus YS (1.12 ± 0.09 versus 0.57 ± 0.09 (Δmm (dyn cm −2 )) × 10 −2 , P < 0.001; 1 dyn = 10 −5 N), but was preserved in OT (0.93 ± 0.08 (Δmm (dyn cm −2 )) × 10 −2 ). BH 4 administration improved FMD by ∼45% in OS (1.00 ± 0.10 (Δmm (dyn cm −2 )) × 10 −2 , P < 0.01 versus baseline), but did not affect FMD in YS or OT. Endothelium‐independent dilatation neither differed between groups at baseline nor changed with BH 4 administration. These results suggest that BH 4 bioactivity may be a key mechanism involved in the impairment of conduit artery EDD with sedentary ageing, and the EDD‐preserving effect of habitual exercise.