Munch D F, Comer H T, Downey J M
Am J Physiol. 1980 Sep;239(3):H438-42. doi: 10.1152/ajpheart.1980.239.3.H438.
Studies of cardiac mechanics, metabolism, and coronary hemodynamics have traditionally been carried out in rhythmically beating hearts. We have developed an isolated rabbit heart preparation that is free from contractions and allows a stable graded ventricular pressure to be established. Rabbit hearts were rapidly excised and perfused at constant pressure with heated (39 degrees C) Tyrode solution bubbled with 98% O2-2% CO2. A latex balloon was inserted into the left ventricle (lv) to adjust lv volume and measure pressure. Nine hearts were depleted of calcium by reducig the calcium concentration in the Tyrode's from 5 to 0.078 mM. When barium (Ba2+) was added to the perfusate, the hearts spontaneously developed pressure that was free of an overriding beat (contracture). The intensity of the contracture increased in a sigmoid fashion as the barium concentration was increased. During contracture balloon pressure ranged between 33.8 +/- 5.0% (SE) (Ba2+ 0.5 mM) and 79.0 +/- 4.5% (Ba2+ 1.5 mM) of control systolic developed pressure Ventricular pressure-volume curves were linear (r > 0.98) and indicated increased ventricular stiffness as barium concentration increased. We believe that barium-induced contracture is a good model of systolic cardiac muscle interactions.
传统上，心脏力学、代谢和冠状动脉血流动力学的研究都是在有节律跳动的心脏上进行的。我们开发了一种离体兔心标本，该标本无收缩现象，并能建立稳定的分级心室压力。兔心被迅速取出，在39摄氏度下，用含98%氧气-2%二氧化碳的泰罗德溶液以恒压灌注。将一个乳胶气球插入左心室以调节左心室容积并测量压力。通过将泰罗德溶液中的钙浓度从5 mM降低到0.078 mM，使9颗心脏缺钙。当向灌注液中加入钡（Ba2+）时，心脏自发产生压力，且无主导搏动（挛缩）。随着钡浓度的增加，挛缩强度呈S形增加。在挛缩过程中，气球压力在对照收缩期产生压力的33.8±5.0%（标准误）（Ba2+ 0.5 mM）至79.0±4.5%（Ba2+ 1.5 mM）之间。心室压力-容积曲线呈线性（r>0.98），表明随着钡浓度的增加，心室僵硬度增加。我们认为钡诱导的挛缩是收缩期心肌相互作用的一个良好模型。
