title: Strain differences in baroceptor reflex in adult Wistar Kyoto rats.
abstract: OBJECTIVE
  A subset of normotensive Sprague-Dawley rats show lower baroreflex sensitivity; however, no previous study investigated whether there are differences in baroreflex sensitivity within this subset. Our study compared baroreflex sensitivity among conscious rats of this specific subtype.
  
  
  METHODS
  Male Wistar Kyoto (WKY) rats (16 weeks old) were studied. Cannulas were inserted into the abdominal aortic artery through the right femoral artery to measure mean arterial pressure (MAP) and heart rate (HR). Baroreflex gain was calculated as the ratio between change in HR and MAP variation (DeltaHR/DeltaMAP) in response to a depressor dose of sodium nitroprusside (SNP, 50 microg/kg, i.v.) and a pressor dose of phenylephrine (PE, 8 microg/kg, i.v.). Rats were divided into four groups: 1) low bradycardic baroreflex (LB), baroreflex gain (BG) between -1 and -2 bpm/mmHg tested with PE; 2) high bradycardic baroreflex (HB), BG < -2 bpm/mmHg tested with PE; 3) low tachycardic baroreflex (LT), BG between -1 and -2 bpm/mmHg tested with SNP and; 4) high tachycardic baroreflex (HT), BG < -2 bpm/mmHg tested with SNP. Significant differences were considered for p < 0.05.
  
  
  RESULTS
  Approximately 37% of the rats showed a reduced bradycardic peak, bradycardic reflex and decreased bradycardic gain of baroreflex while roughly 23% had a decreased basal HR, tachycardic peak, tachycardic reflex and reduced sympathetic baroreflex gain. No significant alterations were noted with regard to basal MAP.
  
  
  CONCLUSIONS
  There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.
authors.affiliation: Department of Medicine, Cardiology Division, Federal Unversity of São Paulo (UNIFESP) - São Paulo/SP, Brazil. valenti@unifesp.br
authors.forename: Vitor E
authors.initials: VE
authors.lastname: Valenti
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: de Abreu
authors.forename: Caio
authors.initials: C
authors.lastname: Imaizumi
authors.forename: Márcio
authors.initials: M
authors.lastname: Petenusso
authors.forename: Celso
authors.initials: C
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY / Q000145:classification; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine