Department of Medicine, Cardiology Division, Federal Unversity of São Paulo (UNIFESP) - São Paulo/SP, Brazil.
Clinics (Sao Paulo). 2010 Feb;65(2):203-8. doi: 10.1590/S1807-59322010000200013.
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.
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.
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.
There is variability regarding baroreflex sensitivity among WKY rats from the same laboratory.
一部分血压正常的 Sprague-Dawley 大鼠表现出较低的压力感受反射敏感性；然而，之前没有研究调查在这个亚组内压力感受反射敏感性是否存在差异。我们的研究比较了这一特定亚组中清醒大鼠的压力感受反射敏感性。
研究雄性 Wistar 京都（WKY）大鼠（16 周龄）。通过右侧股动脉将导管插入腹主动脉以测量平均动脉压（MAP）和心率（HR）。压力感受反射增益计算为 HR 变化与 MAP 变化（DeltaHR/DeltaMAP）之间的比值，以响应静脉注射 50μg/kg 硝普钠（SNP）的降压剂量和静脉注射 8μg/kg 去甲肾上腺素（PE）的升压剂量。大鼠分为四组：1）低心率压力感受反射（LB），用 PE 测试时压力感受反射增益（BG）在-1 到-2 bpm/mmHg 之间；2）高心率压力感受反射（HB），用 PE 测试时 BG < -2 bpm/mmHg；3）低心搏过速压力感受反射（LT），用 SNP 测试时 BG 在-1 到-2 bpm/mmHg 之间；4）高心搏过速压力感受反射（HT），用 SNP 测试时 BG < -2 bpm/mmHg。p < 0.05 被认为有显著差异。
约 37%的大鼠表现出心率降低峰值、心率反射和压力感受反射降低，而约 23%的大鼠基础 HR、心动过速峰值、心动过速反射和交感神经压力感受反射降低。基础 MAP 无明显变化。
来自同一实验室的 WKY 大鼠的压力感受反射敏感性存在差异。
