title: Aspirin and clopidogrel alter core temperature and skin blood flow during heat stress.
abstract: Antithrombotic therapy with oral aspirin (ASA) or clopidogrel (CLO) (Plavix; Bristol-Myers Squibb, Bridgewater, NJ) is associated with an attenuated skin vasodilator response and a greater rate of rise in core temperature in healthy, middle-age individuals during passive heating in a water perfused suit.
  
  
  OBJECTIVE
  The present double-blind, crossover study examined the functional consequences of 7 d of low-dose ASA (81 mg·d) versus CLO (75 mg·d) treatment in 14 healthy, middle-age (50-65 yr) men and women during passive heating in air (40 min at 30°C, 40% relative humidity) followed by exercise (60% V˙O2peak).
  
  
  METHODS
  Oral temperature (Tor) was measured in the antechamber (23.0°C ± 0.1°C) before entering a warm environmental chamber. After 40 min of rest, subjects cycled on a recumbent cycle ergometer for up to 120 min. Esophageal temperature (Tes) and laser Doppler flux were measured continuously, and the latter was normalized to maximal cutaneous vascular conductance (%CVCmax).
  
  
  RESULTS
  Before entry into the environmental chamber there were no differences in Tor among treatments; however, after 40 min of rest in the heat, Tes was significantly higher for ASA and CLO versus placebo (37.2°C ± 0.1°C, 37.3°C ± 0.1°C, vs 37.0°C ± 0.1°C, both P < 0.001), a difference that persisted throughout exercise (P < 0.001 vs placebo). The mean body temperature thresholds for the onset of cutaneous vasodilation were shifted to the right for both ASA and CLO during exercise (P < 0.05).
  
  
  CONCLUSIONS
  ASA and CLO resulted in elevated core temperatures during passive heat stress and shifted the onset of peripheral thermoeffector mechanisms toward higher body temperatures during exercise heat stress.
authors.affiliation: Noll Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Bruning
authors.forename: Jessica D
authors.initials: JD
authors.lastname: Dahmus
authors.forename: W Larry
authors.initials: WL
authors.lastname: Kenney
authors.forename: Lacy M
authors.initials: LM
authors.lastname: Alexander
mesh_terms: D000368:Aged; D001241:Aspirin / Q000494:pharmacology*; D001833:Body Temperature Regulation / Q000187:drug effects*; D000077144:Clopidogrel; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods; D005260:Female; D018882:Heat Stress Disorders / Q000503:physiopathology / Q000517:prevention & control*; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D013817:Thermography / Q000379:methods; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin