Gay R G, Raya T E, Lancaster L D, Lee R W, Morkin E, Goldman S
Department of Internal Medicine, Veterans Administration Medical Center, Tucson 85723.
Am J Physiol. 1988 Jan;254(1 Pt 2):H81-8. doi: 10.1152/ajpheart.1988.254.1.H81.
The cardiovascular system of hypothyroid, normal, and hyperthyroid rats was studied by evaluation of the peripheral venous circulation and left ventricular (LV) systolic and diastolic performance in rats. Cardiac index (CI) and CI during a volume load were measured in open-chest rats. When compared with control, hypothyroid rats showed a decrease in heart rate, aortic pressure, LV systolic pressure, first derivative for LV pressure (LV dP/dt), CI, and CI during a volume load. LV pressure-volume relation was shifted to the right, muscle stiffness was unchanged, and LV relaxation was prolonged. There was a decrease in mean circulatory filling pressure (MCFP) to 6.3 +/- 0.2 from 7.6 +/- 0.2 mmHg in control rats. This was associated with an 11% decrease in unstressed vascular volume and 12% decrease in total blood volume but no change in venous compliance. In hyperthyroid rats there was an increase in heart rate, LV systolic pressure, LV dP/dt, CI, and CI during a volume load. LV chamber stiffness was increased, but muscle stiffness and LV relaxation were unchanged. There was an increase in MCFP to 9.5 +/- 0.3 mmHg and a decrease in venous compliance to 2.65 +/- 0.12 compared with 3.20 +/- 0.09 ml.mmHg-1.kg-1 in control rats. Unstressed vascular volume and total blood volume were unchanged. In conclusion, hyperthyroid rats have augmented LV systolic function and altered diastolic function which, combined with changes in the venous circulation, result in increased venous return and thus cardiac output. In hypothyroid rats both LV systolic and diastolic function are altered. When combined with changes of the venous circulation the changes result in a decrease in cardiac output.
通过评估大鼠的外周静脉循环以及左心室（LV）的收缩和舒张功能，对甲状腺功能减退、正常和甲状腺功能亢进大鼠的心血管系统进行了研究。在开胸大鼠中测量了心脏指数（CI）以及容量负荷时的CI。与对照组相比，甲状腺功能减退大鼠的心率、主动脉压力、左心室收缩压、左心室压力的一阶导数（LV dP/dt）、CI以及容量负荷时的CI均降低。左心室压力-容积关系右移，肌肉僵硬度未改变，左心室舒张延长。平均循环充盈压（MCFP）从对照组大鼠的7.6±0.2 mmHg降至6.3±0.2 mmHg。这与无应激血管容量减少11%和总血容量减少12%相关，但静脉顺应性无变化。甲状腺功能亢进大鼠的心率、左心室收缩压、LV dP/dt、CI以及容量负荷时的CI均增加。左心室腔僵硬度增加，但肌肉僵硬度和左心室舒张未改变。与对照组大鼠的3.20±0.09 ml·mmHg⁻¹·kg⁻¹相比，MCFP增加至9.5±0.3 mmHg，静脉顺应性降低至2.65±0.12。无应激血管容量和总血容量未改变。总之，甲状腺功能亢进大鼠的左心室收缩功能增强且舒张功能改变，这与静脉循环的变化相结合，导致静脉回流量增加，从而使心输出量增加。甲状腺功能减退大鼠的左心室收缩和舒张功能均发生改变。当与静脉循环的变化相结合时，这些变化导致心输出量减少。
