title: Testosterone increases myogenic reactivity of second-order mesenteric arteries in both defective and normal androgen receptor adult male rats.
abstract: BACKGROUND
  Testosterone (T) and the androgen receptor (AR) are involved in mechanisms associated with hypertension and vessel reactivity.
  
  
  OBJECTIVE
  To investigate T and the AR on blood vessel reactivity, testicular feminized male (TFM; AR deficient males) and normal androgen receptor (NAR) male rats were used. Therefore, if the functional AR is necessary for plasma T to regulate vessel responsiveness, TFM males will exhibit altered vessel function compared to NAR males.
  
  
  METHODS
  Adult (16 weeks of age) TFM or NAR males were assigned to the following treatment groups: gonadal intact controls (CONT), castrate (CAST), or castrate with T replacement (CAST+T) with (n=8-10/group).
  
  
  RESULTS
  Plasma T followed a consistent pattern with CAST+T elevated compared to CONT and CAST TFM and NAR males. In addition, CAST plasma T was significantly decreased compared to CONT and CAST+T in TFM and NAR males. In a similar manner for systolic blood pressure (SBP), CAST lowered SBP compared to CONT in both NAR and TFM. Following 8 weeks of treatment, second-order mesenteric artery responses to changes in intraluminal pressure (myogenic reactivity) were analyzed using a pressure arteriograph system. Both TFM (P < 0.05) and NAR (P < 0.05) CAST groups revealed a decrease in myogenic reactivity compared to CONT. Following T treatment the TFM CAST+T myogenic reactivity returned to CONT levels, whereas the NAR CAST+T myogenic reactivity increased a further 10%.
  
  
  CONCLUSIONS
  The results of this study indicate that T differentially regulates mesenteric artery reactivity in TFM and NAR males. Our data also demonstrate that both AR and/or non-AR mediated mechanisms may partially contribute to SBP regulation.
authors.affiliation: Department of Biology, The University of Akron, Akron, Ohio 44325-3908, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Toot
authors.forename: John J
authors.initials: JJ
authors.lastname: Reho
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Novak
authors.forename: Gail
authors.initials: G
authors.lastname: Dunphy
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Ely
authors.forename: Rolando J
authors.initials: RJ
authors.lastname: Ramirez
mesh_terms: D000818:Animals; D008297:Male; D008638:Mesenteric Arteries / Q000378:metabolism / Q000502:physiology*; D024510:Muscle Development; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011944:Receptors, Androgen / Q000378:metabolism*; D013739:Testosterone / Q000502:physiology*
chemical_list: D011944:Receptors, Androgen; D013739:Testosterone