Strain differences in baroceptor reflex in adult Wistar Kyoto rats
Clinics
; 65(2): 203-208, 2010. tab, ilus
Article
in English
| LILACS
| ID: lil-539838
Responsible library:
BR1.1
ABSTRACT
OBJECTIVES: 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 (ÄHR/ÄMAP) in response to a depressor dose of sodium nitroprusside (SNP, 50 µg/kg, i.v.) and a pressor dose of phenylephrine (PE, 8 µg/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 percent of the rats showed a reduced bradycardic peak, bradycardic reflex and decreased bradycardic gain of baroreflex while roughly 23 percent had a decreased basal HR, tachycardic peak, tachycardic reflex and reduced sympathetic baroreflex gain. No significant alterations were noted with regard to basal MAP. CONCLUSION: There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.
Full text:
Available
Collection:
International databases
Database:
LILACS
Main subject:
Blood Pressure
/
Baroreflex
/
Heart Rate
Limits:
Animals
Language:
English
Journal:
Clinics
Journal subject:
Medicine
Year:
2010
Document type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Federal Unversity of São Paulo/BR
/
School of Medicine of ABC/BR