Heslinga J W, Allaart C P, Yin F C, Westerhof N
Laboratory for Physiology, Vrije Universiteit, Amsterdam, The Netherlands.
Am J Physiol. 1997 May;272(5 Pt 2):H2320-6. doi: 10.1152/ajpheart.1997.272.5.H2320.
If intramyocardial pressure (IMP) is the pressure that causes coronary flow to stop, i.e., "backpressure," then it should be equal to the zero-flow perfusion pressure intercept (Pzf). Therefore we determined Pzf and IMP at zero flow (IMPzf) in papillary muscles suspended isometrically in a bath, superfused with a well-oxygenated Tyrode solution (27 degrees C), and perfused with Tyrode solution via the septal artery. For the IMP (servo-null) measurements, we used unbeveled glass micropipettes with a tip diameter of 3-4 microns. During diastolic arrest and systolic contracture (2 mM Ba21), perfusion pressure steps were applied, and the corresponding flow and IMP values were recorded. Fitting of the relationships, yielded Pzf and IMPzf. In the diastolically arrested muscle, perfusion pressure affected IMP. Pzf was much higher in systolically contracted muscle than in diastolically arrested muscle. The IMPzf in both conditions was significantly smaller than Pzf. Thus, even in this preparation with no ventricular pressure, IMP increases during contraction. We conclude that IMP arises from contraction per se but is not the pressure that causes the flow to stop.
如果心肌内压力（IMP）是导致冠状动脉血流停止的压力，即“背压”，那么它应该等于零流量灌注压力截距（Pzf）。因此，我们在恒温浴中对等长悬挂的乳头肌进行了零流量（IMPzf）时Pzf和IMP的测定，用充分氧合的台氏液（27摄氏度）灌流浴槽，并通过间隔动脉用台氏液灌注乳头肌。对于IMP（伺服零位）测量，我们使用了尖端直径为3 - 4微米的无斜面玻璃微吸管。在舒张期停搏和收缩期挛缩（2 mM Ba2+）期间，施加灌注压力阶跃，并记录相应的流量和IMP值。通过对这些关系进行拟合，得出Pzf和IMPzf。在舒张期停搏的肌肉中，灌注压力会影响IMP。收缩期挛缩肌肉中的Pzf比舒张期停搏肌肉中的Pzf高得多。两种情况下的IMPzf均显著小于Pzf。因此，即使在这种没有心室压力的制备中，收缩时IMP也会增加。我们得出结论，IMP源于收缩本身，但并非导致血流停止的压力。
