运动对衰老大鼠心血管功能和肠系膜动脉反应性的影响

目的:研究有氧运动对衰老大鼠心血管功能和肠系膜动脉反应性的影响。方法:健康雄性Wistar大鼠,19月龄,24只,随机分为老年安静组(O-SED)和老年有氧运动组(O-EX)两组,每组12只。O-EX组进行12周15 m/min、60 min/d、5 d/w的跑台运动。另2月龄大鼠12只作为青年对照组(Young)。O-EX组运动12周后,每组选取6只大鼠行股动、静脉插管手术。24 h后,清醒状态下测试、记录大鼠基础血压和心率,然后股静脉注射去甲肾上腺素(NE),观察大鼠血压变化。其余6只进行肠系膜动脉血管环张力测定,检测血管收缩特性。结果:1)老年有氧运动组大鼠基础心率显著低于老年安静组;两组老年大鼠收缩压(SBP)和脉压(PP)均显著高于青年对照组,老年有氧运动组SBP和PP均显著低于老年安静组,但仍高于青年对照组。2)静脉注射NE引起两组老年大鼠的升压反应显著低于青年对照组,老年有氧运动组升压反应大于老年安静组,但仍低于青年对照组;3)各组大鼠肠系膜动脉血管环对NE有浓度依赖性收缩,各组老年大鼠血管对NE的最大收缩反应显著下降,且老年有氧运动组对NE的敏感性高于老年安静组;4)非特异性钾通道阻断剂TEA可使血管收缩,收缩幅度Young组>O-EX组>O-SED组。结论:有氧运动改善衰老大鼠心血管反应性以及肠系膜动脉舒缩功能,其中平滑肌钾通道可能是其重要机制之一。

Effects of Exercise on the Cardiovascular Reactivity and Mesenteric Arterial Function in Senile Rats

Objective To investigate the effects of aerobic exercise on the cardiovascular reactivity and mesenteric arterial function in senile rats.Methods 24 aged male rats(19 months of age) were randomly assigned to sedentary group(O-SED) and exercise group(O-EX).The rats in O-EX underwent a 12-week treadmill training at the speed of 15m/min,60 min per day,and 5 days per week.12 younger rats(2 months of age) were used for comparison(group Y).After 12 weeks,the systolic blood pressure(SBP) and the pulse pressure(PP),heart rate(HR) and cardiovascular reactivity in vivo were monitored in part of the rats in each group via femoral arterial and venous catheters.The mesenteric arteries of the remained animals were isolated for measuring their contractility.Results 1)The HR of group O-EX at rest reduced significantly compared to group O-SED.The SBP and PP in both group O-SED and group O-EX were significantly higher than in group Y,however,they reduced significantly after exercise.2)The pressor responses induced by intravenous injection of norepinephrine(NE) were attenuated in both group O-SED and group O-EX compared to that in group Y,while they were enhanced in group O-EX compared to that in group O-SED.3)NE significantly increased vascular tone in all groups,while the increase in both aged groups was significantly lower than that in group Y.The sensitivity to NE in group O-EX was higher than that in group O-SED.4)Tetraethylammonium induced increase in vascular tone was seen most significantly in group Y,then in group O-EX,followed by group O-SED.Conclusion Exercise induces remodeling of the cardiovascular system and mesenteric arterial function,which may partly due to the increased K+ channel contribution in arteriolar tone regulation.