Burlington R F, Dean M S, Jones S B
Department of Biology, Central Michigan University, Mt. Pleasant 48859.
Am J Physiol. 1989 Feb;256(2 Pt 2):R357-65. doi: 10.1152/ajpregu.1989.256.2.R357.
An isovolumic Langendorff preparation was used to perfuse rat and ground squirrel (Spermophilus tridecemlineatus) hearts at 37, 27, 17, and 7 degrees C. Perfusion pressure (PP) was randomly increased or decreased (40, 60, 70, 110, 120, or 140 mmHg) from a control PP of 90 mmHg. Coronary flow (CF) was measured immediately after each PP change (initial CF) and after stable flow was observed (final CF). Compared with initial flow, final CF was decreased at high PPs or increased at low PPs (autoregulation) in hearts from both species, but rat hearts did not autoregulate CF or develop left ventricular systolic pressure (LVSP) at 7 degrees C. Squirrel hearts generated LVSP at all temperatures and perfusion pressures. LVSP and initial CF were proportional to PP in both species, but squirrel heart LVSP was independent of PP at 7 degrees C. Myocardial O2 consumption (MVO2) was highly correlated with CF in all hearts at 37 degrees C but not at lower temperatures. Squirrel hearts were more efficient (MVO2 vs. HR X LVSP) than rat hearts at low temperatures but less efficient at 37 degrees C. The intrinsic temperature adaptations displayed by squirrel hearts would support continued myocardial function when body temperature and blood pressure fluctuate throughout the stages of hibernation.
采用等容Langendorff灌流法，在37℃、27℃、17℃和7℃下对大鼠和地松鼠（三线松鼠）的心脏进行灌流。灌流压力（PP）从90 mmHg的对照PP随机升高或降低（40、60、70、110、120或140 mmHg）。每次PP改变后立即测量冠状动脉流量（CF）（初始CF），并在观察到稳定流量后测量（最终CF）。与初始流量相比，两种动物心脏在高PP时最终CF降低，在低PP时最终CF升高（自动调节），但大鼠心脏在7℃时不自动调节CF或产生左心室收缩压（LVSP）。地松鼠心脏在所有温度和灌流压力下均能产生LVSP。两种动物的LVSP和初始CF均与PP成正比，但地松鼠心脏LVSP在7℃时与PP无关。在37℃时，所有心脏的心肌耗氧量（MVO2）与CF高度相关，但在较低温度下则不然。在低温下地松鼠心脏比大鼠心脏更高效（MVO2与心率×LVSP），但在37℃时效率较低。当体温和血压在冬眠各阶段波动时，地松鼠心脏所表现出的内在温度适应性将支持心肌功能的持续运行。
