Aiello E A, Grassi de Gende A O
Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina.
Jpn Heart J. 1995 May;36(3):377-88. doi: 10.1536/ihj.36.377.
The uptake and release of Ca2+ were studied in EGTA-skinned aortic strips from spontaneously hypertensive rats (SHR strain: SAP = 191 +/- 5 mmHg, n = 27) and normotensive control rats (WKY strain: SAP = 131 +/- 2 mmHg, n = 25). 45Ca uptake was measured as a function of time (0.5 to 30 min.), at pCa 6.6, in the presence of 10 mM of K oxalate. Skinned aortic strips of SHRs accumulated more Ca2+ after 30 min of uptake than those of WKY rats (0.66 +/- 0.05 vs 0.52 +/- 0.03 nmole.mg-1 wet tissue; p < 0.05). A lower activity of the transport system in the hypertensive group was evidenced by the fraction of these maximal uptake values accumulated after 2 minutes of uptake, 56% compared with 98% in the normotensive group. 45Ca release was assayed in skinned aortic strips preloaded for 30 minutes with 45Ca in the absence of K oxalate and desaturated with washing solutions containing 3 nM free Ca2+. 30 mM of caffeine, 5 microM of norepinephrine or 10 microM of IP3 resulted in greater increases in the rates of Ca2+ efflux in WKY than in SHR aortic strips. Net effluxes of Ca2+ upon stimulation with all these drugs were statistically significant only in the hypertensive group due to its slightly but consistently higher Ca2+ content. Changes in both rate of efflux and net efflux induced by 30 mM of caffeine could be blocked by 0.6 mM of ryanodine. The sarcoplasmic reticulum is characterized in the genetically hypertensive rats by a low transport activity of its Ca(2+)-ATPase, a high Ca2+ content and a Ca2+ release mechanism with low responsiveness to stimulation by caffeine, norepinephrine and IP3.
在自发性高血压大鼠（SHR品系：收缩压=191±5mmHg，n=27）和正常血压对照大鼠（WKY品系：收缩压=131±2mmHg，n=25）的EGTA处理的主动脉条中研究了Ca2+的摄取和释放。在10 mM草酸钾存在下，于pCa 6.6条件下，测定45Ca摄取量随时间（0.5至30分钟）的变化。摄取30分钟后，SHR的去表皮主动脉条比WKY大鼠积累了更多的Ca2+（0.66±0.05对0.52±0.03纳摩尔·毫克-1湿组织；p<0.05）。高血压组转运系统活性较低的证据是摄取2分钟后积累的这些最大摄取值的比例，高血压组为56%，而正常血压组为98%。在不存在草酸钾且用含3 nM游离Ca2+的洗涤溶液去饱和的情况下，对预先加载45Ca 30分钟的去表皮主动脉条进行45Ca释放测定。30 mM咖啡因、5 microM去甲肾上腺素或10 microM肌醇三磷酸（IP3）导致WKY大鼠主动脉条中Ca2+流出速率的增加比SHR大鼠主动脉条更大。由于高血压组Ca2+含量略高但持续较高，用所有这些药物刺激后Ca2+的净流出在高血压组中仅具有统计学意义。30 mM咖啡因诱导的流出速率和净流出的变化可被0.6 mM的兰尼碱阻断。在遗传性高血压大鼠中，肌浆网的特征是其Ca(2+)-ATP酶的转运活性低、Ca2+含量高以及对咖啡因、去甲肾上腺素和IP3刺激的反应性低的Ca2+释放机制。
