运动强度和时间对左右心室影响的比较研究

A Comparative Study on Effects of Exercise Intensity and Duration on Left and Right Ventricular

目的:研究运动强度和时间对左右心室结构、功能和纤维化的影响及它们之间的异同,并初步探讨涉及的可能机理。方法:48只雄性SD大鼠,随机分为对照(Sed)组、中强度运动(ME)组和大强度运动(IE)组,每组又分为8周组和16周组,共6组,每组8只。对照组自由活动,中强度组和大强度组分别以速度15.2 m/min、坡度5°和速度28 m/min、坡度10°的条件每天运动1小时,每周运动5天。最后一次运动后,24小时内记录体重后使用心脏超声检测两心室的舒张末期内径和舒张末期室壁厚度及射血分数。采血后处死,迅速分离心脏。使用Elisa法检测大鼠血清cTnI浓度,天狼星红染色测定两心室的胶原容积分数。结果:在8周和16周时,中强度组和大强度运动组大鼠两心室舒张末期内径都大于对照组。仅16周时大强度组左心室舒张末期内径大于中强度组,其它中强度组和大强度组间左心室或右心室舒张末期内径无差异。随着运动强度增加和运动时间的推移,左心室及右心室舒张末期室壁厚度都有增加的趋势,但无统计学意义。大强度运动8周后,大鼠两心室的射血分数都有低于对照组和中强度组的趋势,但无统计学意义;而大强度运动16周后,两心室射血分数显著低于对照组和中强度组。大强度运动8周或16周后,血清cTnI显著高于对照组和中强度组,中强度组与对照组无差异。16周中强度组或大强度组两个心室的胶原容积分数大于8周时相应的组。8周或16周大强度运动组的右心室胶原容积分数显著大于相应的对照组,且16周时大强度组右心室胶原容积分数显著大于中强度组;而左心室相应的比较无差异。大鼠血清cTnI浓度与左心室和右心室收缩功能均负相关(r=-0.327,P=0.029和r=-0.582,P=0.000);大鼠血清cTnI浓度与左心室胶原容积分数不相关(P=0.276),但与右心室胶原容积分数中度正相关(r=0.597,P=0.000)。结论:1)16周中强度或大强度运动可导致左心室扩张,且运动强度越大扩张程度越大;而右心室扩张只需要8周中强度或大强度运动,但运动强度对右心室扩张程度的影响不明显。2)长期(8周或16周)耐力运动(中强度或大强度)使两心室壁有变肥厚的趋势。左心室肥厚和扩张可能不是同步的:先肥厚再扩张;但右心室肥厚和扩张是同步的。3)大强度耐力运动引起两心室收缩功能短暂性下降与心室损伤有关,且右心室可能比左心室损伤更严重。中强度运动不会引起心室损伤,对心室射血分数影响不大或无影响。4)长期(8周或16周)大强度耐力运动导致右心室胶原容积分数增加,可能是右心室损伤后形成的心肌纤维化,但左心室未见;而16周时中强度组和大强度组两心室的胶原容积分数分别大于8周时对应的组别,可能是8周之后的运动使两心室的心肌细胞继续肥大,细胞外基质也相应增多,并不是纤维化。

Objective To examine the effects of exercise intensity and duration on the structure,func-tion and fibrosis of the left and right ventricular,and to discuss the potential mechanism in these pro-cesses. Methods Forty-eight male Sprague-Dawley rats were randomly divided into a sedentary（Sed）group,a moderate exercise（ME）group and an intensive exercise（IE）group,each of 16. Rats in Sedgroup were not given any training,while those in ME group and IE group run on treadmill at thespeed of 15.2 m/min with the slope gradient of 5° and 28 m/min with the slope gradient of 10 degree1 hour per day,5 days per week. Eight and 16 weeks after the training,we recorded the body weightand measure end-diastolic diameter,end-diastolic wall thickness,and ejection fraction of both ventricu-lars using the ultrasonic testing. All rats were then sacrificed after blood sampling. Elisa was used tomeasure serum cTnI concentration,and sirius red staining was applied to evaluate collagen volume frac-tion of both ventriculars. Results Eight or sixteen weeks after the training,the average bi-ventricularend-diastolic diameter of ME and IE rats was bigger than Sed group. There were no differences inend-diastolic diameter of both ventricular between ME group and IE group after sixteen-week training,but the left ventricular end-diastolic diameter of IE group was greater than ME group. As exercise in-tensive increased and time accumulated,the end-diastolic wall thickness of both ventriculars increasedbut without statistical significance. At sixteen-week intervention,the bi-ventricular ejection fraction ofIE rats was significantly lower than Sed and ME groups,while there was a decreasing trend eightweeks earlier without significant differences. After 8 or 16 weeks of training,the serum cTnI was signifi-cantly higher in IE rats than Sed group or ME group,but there was no significant differences betweenME group and Sed group. After 16 weeks＇ exercises,the average bi-ventricular collagen volume frac-tion of ME or IE group was greater than that after 8 weeks＇ exercises. The average collagen volumefraction of the right ventricular was greater than Sed group at the same time points,and after sixteen-week training the right ventricular collagen volume fraction in IE group was significantly greater thanME group. However,there were no significant differences in the measurement of the left side among dif-ferent groups. The serum cTnI was negatively correlated with the left and right ventricular systolic func-tion（r=- 0.327,P=0.029 and r=- 0.582,P=0.000）. Moreover,it was positively correlated with theright ventricular collagen volume fraction moderately,but had no correlation with the left ventricular col-lagen volume fraction. Conclusion（1）Sixteen-week moderate and intensive exercise result in left ventric-ular dilation,and the dilation increases with the increase of the exercise intensity. Only 8 weeks＇ exer-cise at the same intensity can lead to right ventricular dilation,but exercise intensity has little influ-ence on the right ventricular dilation.（2）Long- term moderate or intensive endurance exercises maycause bi-ventricular hypertrophy potentially. The left ventricular hypertrophy and dilation may not besynchronous with hypertrophy followed by dilation,while the right ventricular hypertrophy and dilationis synchronous.（3）The temporary decrease in bi-ventricular systolic function after intensive enduranceexercise may be caused by ventricular injury,with more serious injury in the right ventricular than inthe left. Moderate exercises don＇t cause ventricular injury,thus there is little or no influence on ejec-tion fraction.（4）Long-term（8 or 16 weeks）moderate or intensive endurance exercises can increase theright ventricular collagen volume fraction,which may indicate cardiac fibrosis following right ventricularinjury but not in the left ventricular. The bi-ventricular collagen volume fraction at sixteenth week inME and IE rats are greater than corresponding rats at eighth week. It may result from the hypertrophyof bi-ventricular cardiomyocyte after 8-week training,followed by increase in the extracellular matrixbut not cardiac fibrosis.