Yamada M, Hanai H, Kaneko E, Fujita M
First Department of Medicine, Hamamatsu University School of Medicine, Japan.
Proc Soc Exp Biol Med. 1993 Sep;203(4):440-5. doi: 10.3181/00379727-203-43620.
Recently, hypertension research has focused on altered cytosolic free Ca2+, [Ca2+]i, in cells of spontaneously hypertensive rats (SHR). In this work, a mechanism(s) responsible for regulating [Ca2+]i was studied with duodenal epithelial cells isolated from SHR and their control, normotensive Wistar-Kyoto rats (WKY). The equal specific activity of sucrase, an enzyme characteristic of microvilli, in both mucosal scrapings and isolated cells from SHR and WKY suggested that mucosal density of enterocytes was not largely different between the two strains. [Ca2+]i of the isolated cells was estimated with fura-2. Upon incubation in the presence of CaCl2, [Ca2+]i increased to a larger extent in SHR than in WKY cells. Ca2+ efflux based on measurements of [Ca2+]i was decreased in SHR cells. Correspondingly, it was found that 45Ca efflux at 10 sec was lower for SHR cells than for WKY cells. Specific activities of Ca(2+)-stimulated and Ca2+/calmodulin-stimulated ATPases in basolateral plasma membrane preparations were reduced in SHR cells. These results indicated that Ca2+ efflux was decreased by reduction in Ca(2+)-pumping ATPase activity in SHR enterocytes.
最近，高血压研究聚焦于自发性高血压大鼠（SHR）细胞中胞质游离Ca2+（[Ca2+]i）的改变。在这项研究中，利用从SHR及其对照正常血压的Wistar-Kyoto大鼠（WKY）分离的十二指肠上皮细胞，研究了调节[Ca2+]i的机制。SHR和WKY的黏膜刮片及分离细胞中蔗糖酶（微绒毛的一种特征性酶）的比活性相同，这表明两品系肠上皮细胞的黏膜密度没有很大差异。用fura-2测定分离细胞的[Ca2+]i。在CaCl2存在下孵育时，SHR细胞的[Ca2+]i升高幅度大于WKY细胞。基于[Ca2+]i测量的Ca2+外流在SHR细胞中减少。相应地，发现SHR细胞在10秒时的45Ca外流低于WKY细胞。SHR细胞基底外侧质膜制剂中Ca2+刺激的ATP酶和Ca2+/钙调蛋白刺激的ATP酶的比活性降低。这些结果表明，SHR肠上皮细胞中Ca2+泵ATP酶活性降低导致Ca2+外流减少。
