title: Infusion of ATP increases leg oxygen delivery but not oxygen uptake in the initial phase of intense knee-extensor exercise in humans.
abstract: The present study examined whether an increase in leg blood flow and oxygen delivery at the onset of intense exercise would speed the rate of rise in leg oxygen uptake. Nine healthy men (25 ± 1 years old, mean ± SEM) performed one-leg knee-extensor exercise (62 ± 3 W, 86 ± 3% of incremental test peak power) for 4 min during a control setting (CON) and with infusion of ATP into the femoral artery in order to increase blood flow before and during exercise. In the presence of ATP, femoral arterial blood flow and O2 delivery were higher (P < 0.001) at the onset of exercise and throughout exercise (femoral arterial blood flow after 10 s, 5.1 ± 0.5 versus 2.7 ± 0.3 l min(-1); after 45 s, 6.0 ± 0.5 versus 4.1 ± 0.4 l min(-1); after 90 s, 6.6 ± 0.6 versus 4.5 ± 0.4 l min(-1); and after 240 s, 7.0 ± 0.6 versus 5.1 ± 0.3 l min(-1) in ATP and CON conditions, respectively). Leg oxygen uptake was not different in ATP and CON conditions during the first 20 s of exercise but was lower (P < 0.05) in the ATP compared with CON conditions after 30 s and until the end of exercise (30 s, 436 ± 42 versus 549 ± 45 ml min(-1); and 240 s, 705 ± 31 versus 814 ± 59 ml min(-1) in ATP and CON, respectively). Lactate release was lower after 60, 120 and 180 s of exercise with ATP infusion. These results suggest that O2 delivery is not limiting the rise in skeletal muscle oxygen uptake in the initial phase of intense exercise.
authors.affiliation: Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark mnyberg@nexs.ku.dk.
authors.forename: Michael
authors.initials: M
authors.lastname: Nyberg
authors.affiliation: Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark Team Danmark (Danish elite sport organization), Copenhagen, Denmark.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Christensen
authors.affiliation: Copenhagen Muscle Research Centre, Copenhagen, Denmark Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Stefan P
authors.initials: SP
authors.lastname: Mortensen
authors.affiliation: Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Hellsten
authors.affiliation: Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Bangsbo
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000328:Adult; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000187:drug effects*; D012039:Regional Blood Flow / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000255:Adenosine Triphosphate; D010100:Oxygen