THE ECONOMY OF ISOMETRIC FORCE DEVELOPMENT, MYOSIN ISOENZYME PATTERN AND MYOFIBRILLAR ATPASE ACTIVITY IN NORMAL AND HYPOTHYROID RAT MYOCARDIUM
THE ECONOMY OF ISOMETRIC FORCE DEVELOPMENT, MYOSIN ISOENZYME PATTERN AND MYOFIBRILLAR ATPASE ACTIVITY IN NORMAL AND HYPOTHYROID RAT MYOCARDIUM
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DOI：
10.1161/01.res.56.1.78
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发表时间：
1985-01-01
影响因子：
20.1
通讯作者：
ALPERT, NR
中科院分区：
文献类型：
--
作者：
HOLUBARSCH, C;GOULETTE, RP;ALPERT, NR
饮水中加入0.8 mg/ml丙硫尿嘧啶可诱导Wistar-Kyoto大鼠甲状腺功能减退。以12次/分（21度）等距收缩，测量丙硫脲嘧啶处理和对照大鼠左心室乳头肌制剂的初始热量、总活动相关热量和静息热率。C)，采用Hill型、平面真空沉积的Bi和Sb型亲热菌。在丙基硫脲嘧啶制剂中，相对于对照，峰值时间张力从288 .+-增加。27（平均值+-）SD)至411。25 ms (P < 0.001)， dp/dtmax从38.3±-下降。9.5至20.4 .+-。3.5 g .cntdot。mm-2/s (P < 0.001)，峰值发展张力从6.11 +-下降。1.75至4.64 .+-。0.89 .cntdot。mm-2 （P < 0.05）。在丙基硫脲嘧啶制剂中，当归一化到峰值抽搐张力或张力时间积分时，初始热量分别显著（P < 0.001）降低了27%或43%。在乳头肌被破伤风的实验中，丙硫脲嘧啶制剂的总活动相关热量与张力时间积分的线性函数斜率降低了43% (P < 0.001)，表明等长张力维持的经济程度有所提高。丙硫脲嘧啶组左心室壁肌球蛋白同工酶以及乳头状肌心肌的主要肌球蛋白同工酶为V3型，而对照组为V1型。肌纤维肌动球蛋白ca - mg刺激的ATP活性显著（P < 0.02）低于55 .+-。18（对照）至31 .+-。8 nmol Pi离子/mg。分钟(丙基硫氧嘧啶)。肌原纤维肌球蛋白钙刺激的ATP活性也从294 .+-显著（P < 0.01）降低。98（对照）至85。25 nmol Pi离子/mg。分钟(丙基硫氧嘧啶)。有证据表明丙硫脲嘧啶心肌产生和维持力量的经济性增加，这与肌球蛋白的结构变化（同工酶模式的改变）和肌纤维ATP活性的相关变化是平行的。观察到的肌热数据反映了丙硫脲嘧啶心肌的过桥循环减慢，考虑到产生力量的经济性增加，这并不一定被解释为有害的。
Hypothyroidism was induced in Wistar-Kyoto rats by adding propylthiouracil to the drinking water (0.8 mg/ml). Initial heat, total activity-related heat and resting heat rate were measured in left ventricular papillary muscle preparations of propylthiouracil-treated and control rats contracting isometrically at 12 beats/min (21.degree. C), using Hill type, planar vacuum-deposited Bi and Sb thermophiles. In the propylthiouracil preparations, relative to control, time-to-peak tension increased from 288 .+-. 27 (mean .+-. SD) to 411 .+-. 25 ms (P < 0.001), dp/dtmax decreased from 38.3 .+-. 9.5 to 20.4 .+-. 3.5 g .cntdot. mm-2/s (P < 0.001) and peak developed tension decreased from 6.11 .+-. 1.75 to 4.64 .+-. 0.89 .cntdot. mm-2 (P < 0.05). In the propylthiouracil preparations, initial heat was significantly (P < 0.001) reduced by 27 or 43% when normalized to peak twitch tension or tension-time integral, respectively. In experiments where the papillary muscles were tetanized, the slope of the linear function of total activity-related heat vs. tension-time integral was decreased by 43% (P < 0.001) in the propylthiouracil preparations, indicating an improved economy of isometric tension maintenance. The predominant myosin isoenzyme of the left ventricular wall, as well as the papillary muscle myocardium, was the V3 variety in the propylthiouracil animals, in contrast to V1 in the controls. Myofibrillar actomyosin Ca-Mg-stimulated ATP activity was significantly (P < 0.02) decreased from 55 .+-. 18 (control) to 31 .+-. 8 nmol Pi ion/mg .cntdot. min (propylthiouracil). The myofibrillar myosin Ca-stimulated ATP activity was also significantly (P < 0.01) decreased from 294 .+-. 98 (control) to 85 .+-. 25 nmol Pi ion/mg .cntdot. min (propylthiouracil). Evidence of increased economy of force generation and maintenance in propylthiouracil myocardium, which is paralleled by structural changes of myosin (shifts in the isoenzyme pattern) and associated changes of myofibrillar ATP activity was found. The observed myothermal data reflect slowed crossbridge cycling in propylthiouracil myocardium, which must not necessarily be interpreted as being detrimental, in view of the increased economy of force generation.