title: Intra-strain variations of baroreflex sensitivity in young Wistar-Kyoto rats.
abstract: OBJECTIVE
  To compare baroreflex sensitivity among conscious rats of the same strain.
  
  
  METHODS
  Male WKY rats (eight 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 variation of HR in function of the MAP variation (?HR/?MAP) tested with a depressor dose of sodium nitroprusside (SNP, 50 microg/kg, iv) and with a pressor dose of phenylephrine (PE, 8 microg/kg, iv). We divided the rats into four groups: 1) Low bradycardic baroreflex (LB), 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 82% of the rats presented reduced bradycardic reflex while 22 showed attenuated tachycardic reflex. No alterations were noted regarding basal MAP and HR, tachycardic and bradycardic peak and HR range.
  
  
  CONCLUSIONS
  There was alteration in baroreflex sensitivity among rats of the same strain. Care should be taken when interpreting studies employing WKY as a control for the SHR.
authors.affiliation: Department of Medicine, Cardiology Division, UNIFESP, 04039-032, São Paulo, SP, Brazil. valenti@unifesp.br
authors.forename: Vitor E
authors.initials: VE
authors.lastname: Valenti
authors.forename: Caio
authors.initials: C
authors.lastname: Imaizumi
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: de Abreu
authors.forename: Eduardo
authors.initials: E
authors.lastname: Colombari
authors.forename: Monica A
authors.initials: MA
authors.lastname: Sato
authors.forename: Celso
authors.initials: C
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D017704:Baroreflex; D001794:Blood Pressure; D006339:Heart Rate; D008297:Male; D051381:Rats; D011921:Rats, Inbred WKY; D013045:Species Specificity