Enhanced endothelin-1-mediated leg vascular tone in healthy older subjects.
Advanced age is associated with a decreased leg blood flow and reduced physical activity. Endothelin (ET-1), a powerful vasoconstrictor, may play a role in the increased leg vascular tone in older men. objectives: to assess the ET-1-mediated vascular tone in the legs of healthy sedentary older men, both before and after 8 wk of exercise training. methods: in 8 younger subjects (19-50 yr) and 8 older men (67-76 yr), bilateral leg blood flow was measured using venous occlusion plethysmography before and after antagonizing ET-1 (using selective ET(A/B)-receptor antagonists). In older men, reversibility of the observations was assessed after 8 wk of cycling. results: ET-receptor inhibition increased leg blood flow significantly more in older men compared with younger individuals (29 +/- 9% and 10 +/- 4%, respectively, P < 0.05). Eight-week cycling training increased baseline blood flow in older men. The blood flow response to ET-receptor inhibition in older men was not affected by the training program (25 +/- 8%, P > 0.05 for comparison with pretraining). The flow ratio (blood flows infused leg/noninfused leg) decreased significantly by training from 26 +/- 8% to 7+3% (P < 0.05).


CONCLUSIONS
the increased baseline vascular tone in aging is at least in part mediated by the endothelin. Eight-weeks cycling training in older sedentary men decreased leg vascular tone and seems to partly decrease the ET-1-mediated vascular tone.
Thijssen
Dick H J
DH
Department of Physiology, Radboud University Nijmegen Medical Centre, Geert Grooteplein-Noord 21, 6525 EZ, Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Rongen
Gerard A
GA
van Dijk
Arie
A
Smits
Paul
P
Hopman
Maria T E
MT
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D016022:Case-Control Studies; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000502:physiology*; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects
D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1