弹性蛋白酶对离体豚鼠乳头肌弹性组织收缩性和形态的影响。

Effects of elastase on contractility and morphology of elastic tissue in isolated guinea pig papillary muscles.

作者信息

Sato T, Imanishi S, Arita M, Shimada T

机构信息

Department of Physiology, Oita Medical University, Japan.

出版信息

Heart Vessels. 1993;8(2):71-8. doi: 10.1007/BF01744386.

DOI:10.1007/BF01744386

PMID:8314740

Abstract

Elastase (ELA) is an enzyme catalyzing the digestion of elastin, an essential constituent of elastic fibers. Using isolated guinea pig papillary muscles, we examined the effect of ELA (3 x 10(-7) -3 x 10(-4) g/ml) on resting tension (RT) and twitch tension (TT). The effects of ELA on elastic fibers located in the subendocardium were examined histologically. A relatively high concentration of ELA (3 x 10(-4) g/ml) increased TT transiently, with progressive decreases in RT. In contrast, a relatively low concentration (3 x 10(-5) g/ml) decreased both TT and RT straightforwardly. Much lower concentrations (3 x 10(-6) -3 x 10(-7) g/ml) did not reveal significant effects. The ELA-induced increases in TT were unaffected in the presence of atenolol (10(-5) g/ml), ouabain (10(-7) M) or ryanodine (10(-6)M). ELA did not increase the maximum rate of rise of slow action potentials recorded using standard microelectrodes. ELA (3 x 10(-5) g/ml) decreased the maximum TT obtained at optimal RT or Lmax, and decreased the slope of the ascending and descending limbs of the TT-RT relation curve (Frank-Starling's). Electron-microscopic findings revealed that subendocardial elastin was mostly digested at ELA concentrations of 3 x 10(-5) -3 x 10(-4) g/ml. These findings suggest that the decrease of RT by ELA may be, at least in part, caused by a decomposition of the elastic fibers. On the other hand, the increase of TT by ELA could not be attributed to a release of endogenous catecholamine, an inhibition of Na+, K(+)-pump, a release of Ca2+ from sarcoplasmic reticulum, or an increase of slow inward current.

摘要

弹性蛋白酶（ELA）是一种催化弹性蛋白消化的酶，弹性蛋白是弹性纤维的重要组成部分。我们使用分离的豚鼠乳头肌，研究了ELA（3×10⁻⁷ - 3×10⁻⁴ g/ml）对静息张力（RT）和收缩张力（TT）的影响。通过组织学方法研究了ELA对心内膜下弹性纤维的作用。相对较高浓度的ELA（3×10⁻⁴ g/ml）可使TT短暂增加，同时RT逐渐降低。相比之下，相对较低浓度（3×10⁻⁵ g/ml）则直接降低TT和RT。更低的浓度（3×10⁻⁶ - 3×10⁻⁷ g/ml）未显示出显著影响。在存在阿替洛尔（10⁻⁵ g/ml）、哇巴因（10⁻⁷ M）或ryanodine（10⁻⁶ M）的情况下，ELA诱导的TT增加不受影响。ELA并未增加使用标准微电极记录的慢动作电位的最大上升速率。ELA（3×10⁻⁵ g/ml）降低了在最佳RT或Lmax时获得的最大TT，并降低了TT-RT关系曲线（弗兰克-斯塔林曲线）上升和下降支的斜率。电子显微镜检查结果显示，在心内膜下弹性蛋白在ELA浓度为3×10⁻⁵ - 3×10⁻⁴ g/ml时大多被消化。这些发现表明，ELA导致的RT降低可能至少部分是由弹性纤维的分解引起的。另一方面，ELA导致的TT增加不能归因于内源性儿茶酚胺的释放、Na⁺、K⁺-泵的抑制、肌浆网中Ca²⁺的释放或慢内向电流的增加。