Distensibility of left atrium in normotensive and spontaneously hypertensive rats.
Distensibility of left atrium in normotensive and spontaneously hypertensive rats.
复制标题
正常血压和自发性高血压大鼠左心房的扩张。
DOI：
--
复制
发表时间：
1980
期刊：
影响因子：
--
通讯作者：
P. Thoren
中科院分区：
文献类型：
--
作者：
S. Ricksten;T. Yao;B. Ljung;P. Thoren
在自发性高血压大鼠（SHR）左心房机械感受器重置。因此，SHR的左心房压力必须几乎是血压正常大鼠的两倍，才能产生相当程度的受体激活和反射交感神经抑制。本研究旨在探讨这种重置是否是由于SHR心房扩张性降低所致。因此，静态负载长度的关系进行了研究，从11对雄性SHR和Wistar京都大鼠（WKR）的离体左心房条。每次实验后，将条带固定在4 mN的被动张力下，并在组织学上测定平均壁厚。此外，在SHR和WKR无搏动的离体左心房上研究了压力-容积关系。扩张性在此定义为当舒张压从2.5 mmHg快速（0.5- 1 s，“动态”扩张）或缓慢（3 min，“静态”扩张）增加至12.5 mmHg时的体积增加%。SHR和WKR的心房壁厚度无显著差异，但SHR在80%以上的伸长期间施加的每横截面积的被动力（mN）更大（P <0.05）。SHR的“动态”容积扩张性显著低于SHR（P <0.01），而“静态”容积扩张性无显著差异。SHR左心房壁动态扩张性降低至少可以部分解释快速充盈期心房受体的重调定。
In spontaneously hypertensive rats (SHR) left atrial mechanoreceptors are reset. Thus, left atrial pressure must be almost twice as high in SHR as in normotensive rats to produce comparable degrees of receptor activation and reflex sympathetic inhibition. The present study was performed to investigate whether this resetting is due to a decreased atrial distensibility in SHR. Static load-length relationships were therefore investigated on isolated left atrial strips from 11 pairs of male SHR and Wistar Kyoto rats (WKR). After each experiment the strips were fixed at a passive tension of 4 mN and the average wall thickness was determined histologically. Furthermore, pressure-volume relationships were studied on non-beating, isolated left atria from SHR and WKR. Distensibility was here defined as % volume increase when LAP was increased from 2.5 to 12.5 mmHg either rapidly (0.5--1 s, "dynamic" distension) or slowly (3 min, "static" distension). Atrial wall thickness did not differ significantly in SHR and WKR, but the passive force (mN) per cross sectional area exerted during elongation above 80% was greater (P less than 0.05) in SHR. Also the "dynamic", but not the "static" volume distensibility was significantly lower in SHR (P less than 0.01). The decreased dynamic distensibility of SHR left atrial walls can at least partly explain the resetting of the atrial receptors activated during the rapid filling phase.