title: The effect of purinergic P2 receptor blockade on skeletal muscle exercise hyperemia in miniature swine.
abstract: OBJECTIVE
  ATP could play an important role in skeletal muscle blood flow regulation by inducing vasodilation via purinergic P2 receptors. This study investigated the role of P2 receptors in exercise hyperemia in miniature swine.
  
  
  METHODS
  We measured regional blood flow with radiolabeled-microsphere technique and systemic hemodynamics before and after arterial infusion of the P2 receptor antagonist reactive blue 2 during treadmill exercise (5.2 km/h, ~60 % VO2max) and arterial ATP infusion in female Yucatan miniature swine (~29 kg).
  
  
  RESULTS
  Mean blood flow during exercise from the 16 sampled skeletal muscle tissues was 138 ± 18 mL/min/100 g (mean ± SEM), and it was reduced in 11 (~25 %) of the 16 sampled skeletal muscles after RB2 was infused. RB2 also lowered diaphragm blood flow and kidney blood flow, whereas lung tissue blood flow was increased (all P < 0.05). Infusion of RB2 increased arterial lactate concentration during exercise from 1.6 ± 0.5 to 3.4 ± 0.6 mmol/L and heart rate from 216 ± 12 to 230 ± 9 beats/min, whereas blood pressure was unaltered. Arterial ATP infusion caused a ~twofold increase in blood flow in 15 of the 16 sampled muscle tissues and this effect was abolished after RB2 infusion.
  
  
  CONCLUSIONS
  These results indicate that P2 receptors play a role in regulating skeletal muscle blood flow during exercise in miniature swine.
authors: Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, J.B.Winsløwsvej 21-3, 5000, Odense C, Denmark, smortensen@health.sdu.dk.
authors: S P
authors: SP
authors: Mortensen
authors: R M
authors: RM
authors: McAllister
authors: H T
authors: HT
authors: Yang
authors: Y
authors: Y
authors: Hellsten
authors: M H
authors: MH
authors: Laughlin
mesh_terms: D000818:Animals; D005260:Female; D006940:Hyperemia / Q000209:etiology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D005082:Physical Exertion; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects; D013552:Swine; D013556:Swine, Miniature; D014227:Triazines / Q000494:pharmacology*
chemical_list: D058921:Purinergic P2Y Receptor Antagonists; D014227:Triazines; C012842:Cibacron Blue F 3GA