自发性高血压大鼠和Wistar-Kyoto正常血压大鼠培养的主动脉平滑肌细胞中质膜钙泵介导的钙外流和大量胞质游离钙

Plasma membrane calcium pump-mediated calcium efflux and bulk cytosolic free calcium in cultured aortic smooth muscle cells from spontaneously hypertensive and Wistar-Kyoto normotensives rats.

作者信息

Monteith G R, Kable E P, Chen S, Roufogalis B D

机构信息

Department of Pharmacy, University of Sydney, NSW, Australia.

出版信息

J Hypertens. 1996 Apr;14(4):435-42.

PMID:8761891

Abstract

OBJECTIVE

To compare the efficacy of the calcium pump-mediated calcium efflux pathway in spontaneously hypertensive rats (SHR) with that in Wistar-Kyoto normotensive rats (WKY), at rest and after angiotensin II stimulation.

DESIGN

The intracellular free calcium concentration and calcium-45 efflux were measured in parallel, in cultured aortic smooth muscle cells isolated from 10-week-old male SHR and WKY rats.

METHODS

The intracellular free calcium concentration and calcium-45 efflux were studied in confluent vascular smooth muscle cells in culture. Experiments were performed in the absence of added extracellular calcium and sodium. Fura-2 was used to measure basal and angiotensin II-stimulated intracellular free calcium concentration. Effluxed calcium-45 was measured over 5s intervals to determine basal and angiotensin II-stimulated calcium efflux rates in SHR and in WKY rats.

RESULTS

No significant difference between SHR and WKY rats was observed in basal intracellular free calcium concentration or 100nmol/l angiotensin II-stimulated peak intracellular free calcium concentration. However, significantly elevated basal and 100 nmol/l angiotensin II-stimulated calcium-45 efflux rates were found in SHR. The calcium-45 efflux rates in SHR were elevated when the efflux was normalized with respect to the bulk intracellular free calcium concentration. The time taken to reach the maximum calcium-45 efflux rate after angiotensin II stimulation was reduced in SHR compared with that in WKY rats and was dose-dependent in both rat strains.

CONCLUSION

The calcium-pump mediated calcium efflux pathway appears to be more efficient in SHR. This may be the result of post-translational modification, enhanced calcium pump sites in a critical region of the membrane, or the presence of a pool of calcium near the plasma membrane that is not readily detected by cytosolic Fura-2 but is higher in SHR both before and after angiotensin II stimulation.

摘要

目的

比较自发性高血压大鼠（SHR）与Wistar-Kyoto正常血压大鼠（WKY）在静息状态及血管紧张素II刺激后钙泵介导的钙外流途径的功效。

设计

对从10周龄雄性SHR和WKY大鼠分离的培养主动脉平滑肌细胞同时测量细胞内游离钙浓度和45钙外流。

方法

在培养的汇合血管平滑肌细胞中研究细胞内游离钙浓度和45钙外流。实验在无细胞外钙和钠添加的情况下进行。用Fura-2测量基础及血管紧张素II刺激后的细胞内游离钙浓度。以5秒间隔测量流出的45钙，以确定SHR和WKY大鼠的基础及血管紧张素II刺激后的钙外流速率。

结果

在基础细胞内游离钙浓度或100nmol/l血管紧张素II刺激后的峰值细胞内游离钙浓度方面，SHR和WKY大鼠之间未观察到显著差异。然而，在SHR中发现基础及100nmol/l血管紧张素II刺激后的45钙外流速率显著升高。当45钙外流相对于总体细胞内游离钙浓度进行归一化时，SHR中的45钙外流速率升高。与WKY大鼠相比，SHR中血管紧张素II刺激后达到最大45钙外流速率所需的时间缩短，且在两种大鼠品系中均呈剂量依赖性。