Scrogin K E, Hatton D C, McCarron D A
Department of Medical Psychology, Oregon Health Sciences University, Portland 97201-3098.
Am J Physiol. 1991 Oct;261(4 Pt 2):R945-9. doi: 10.1152/ajpregu.1991.261.4.R945.
Blood pressure increases associated with salt loading in the spontaneously hypertensive rat (SHR) are attenuated with increased dietary calcium. To assess the cardiovascular effects of these nutrients during stress, blood pressure and sympathoadrenal responses to stress were compared in salt-sensitive SHRs fed diets containing normal (0.73%) or high (8.0%) NaCl combined with either low (0.2%) or high (2.0%) calcium. NaCl-loaded rats showed increased blood pressure and exaggerated plasma epinephrine changes during restraint stress. Elevated blood pressure responses to exogenous NE were also observed with high salt intake. Supplementary calcium reduced blood pressure and attenuated the hypertensive effect of NaCl during restraint stress. Animals fed the high calcium diets had lower plasma epinephrine levels while vascular reactivity was not affected. The results indicate that increased sympathoadrenal activity and vascular reactivity contribute to elevated blood pressure and exaggerated pressor responses produced by NaCl loading in the salt-sensitive SHR. However, the hypotensive effects of dietary calcium appear to be related to sympathoadrenal activity but not vascular reactivity.
自发性高血压大鼠（SHR）中，随着钠负荷增加而出现的血压升高会因膳食钙增加而减弱。为了评估应激期间这些营养素对心血管系统的影响，我们比较了喂食含正常（0.73%）或高（8.0%）氯化钠以及低（0.2%）或高（2.0%）钙饮食的盐敏感型SHR的血压和对应激的交感肾上腺反应。摄入氯化钠的大鼠在束缚应激期间血压升高，血浆肾上腺素变化加剧。高盐摄入时，对外源性去甲肾上腺素的血压反应也会升高。补充钙可降低血压，并减轻束缚应激期间氯化钠的升压作用。喂食高钙饮食的动物血浆肾上腺素水平较低，而血管反应性不受影响。结果表明，交感肾上腺活动增强和血管反应性增加导致盐敏感型SHR中因钠负荷而出现的血压升高和升压反应加剧。然而，膳食钙的降压作用似乎与交感肾上腺活动有关，而与血管反应性无关。
