Tanaka M, Schmidlin O, Yi S L, Bollen A W, Morris R C
Department of Medicine, General Clinical Research Center, University of California, 1202 Moffitt Hospital, San Francisco, CA 94143-0126, USA.
Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14748-52. doi: 10.1073/pnas.94.26.14748.
The stroke-prone spontaneously hypertensive rat (SHRSP) is a genetically determined model of "salt-sensitive" stroke and hypertension whose full phenotypic expression is said to require a diet high in Na+ and low in K+. We tested the hypothesis that dietary Cl- determines the phenotypic expression of the SHRSP. In the SHRSP fed a normal NaCl diet, supplementing dietary K+ with KCl exacerbated hypertension, whereas supplementing either KHCO3 or potassium citrate (KB/C) attenuated hypertension, when blood pressure (BP) was measured radiotelemetrically, directly and continually. Supplemental KCl, but not KB/C, induced strokes, which occurred in all and only those rats in the highest quartiles of both BP and plasma renin activity (PRA). PRA was higher with KCl than with KB/C. These observations demonstrate that with respect to both severity of hypertension and frequency of stroke the phenotypic expression of the SHRSP is (i) either increased or decreased, depending on whether the anionic component of the potassium salt supplemented is, or is not, Cl-; (ii) increased by supplementing Cl- without supplementing Na+, and despite supplementing K+; and hence (iii) both selectively Cl--sensitive and Cl--determined. The observations suggest that in the SHRSP selectively supplemented with Cl- the likelihood of stroke depends on the extent to which both BP and PRA increase.
易中风自发性高血压大鼠（SHRSP）是一种由基因决定的“盐敏感型”中风和高血压模型，据说其完整的表型表达需要高钠低钾饮食。我们检验了膳食氯离子决定SHRSP表型表达的假设。在喂食正常氯化钠饮食的SHRSP中，用氯化钾补充膳食钾会加剧高血压，而当通过无线电遥测直接连续测量血压（BP）时，补充碳酸氢钾或柠檬酸钾（KB/C）可减轻高血压。补充氯化钾而非KB/C会诱发中风，中风发生在所有且仅在血压和血浆肾素活性（PRA）最高四分位数的大鼠中。与KB/C相比，氯化钾组的PRA更高。这些观察结果表明，就高血压的严重程度和中风频率而言，SHRSP的表型表达（i）要么增加要么减少，这取决于补充的钾盐的阴离子成分是否为氯离子；（ii）在不补充钠离子且补充钾离子的情况下，通过补充氯离子而增加；因此（iii）既是选择性氯离子敏感的又是由氯离子决定的。这些观察结果表明，在选择性补充氯离子的SHRSP中，中风的可能性取决于血压和PRA升高的程度。
