Factors contributing to increases in circulating hypertensive peptides in genetic hypertension

1)探讨高盐摄入对SHR和WKY肾交感神经活动（RSNA）心肺气压反射控制的影响。与盐摄入正常的WKY相比，盐摄入正常的SHR组刺激（<DELTA>左舒张末压）-反应（<DELTA> RSNA）关系向更高的压力范围转移。高盐摄入降低了SHR和WKY的反射增益。然而，盐负荷引起的增益变化在SHR和wky之间具有可比性。2)我们还研究了心房钠素肽（ANP）的释放对体外轨道拉伸的响应。我们发现，首先，尽管静息张力保持增加，但ANP释放随时间逐渐减少，这表明ANP释放对心房拉伸的反应发生了适应。其次，我们发现，当心房在地尔硫卓<10^(-5)> M的介质或无钙介质中拉伸时，ANP不发生释放。然而，尽管地尔硫卓<10^(-5)> m，但以300次/分钟的频率重复拉伸会增加ANP释放。这些结果表明，活跃的肌肉收缩或钙进入肌细胞并不是ANP释放的先决条件。

1) We investigated the effects of high salt intake on cardiopulmonary baroreflex control of renal sympathetic nerve activity (RSNA) in SHR and WKY. The stimulus ( <DELTA> LV end-diastolic pressure)-response ( <DELTA> RSNA) relationship in SHR with normal salt intake was shifted toward a higher pressure range compared with that in WKY with normal salt intake. High salt intake decereased the gain of the reflex both in SHR and WKY. However, changes in the gain caused by salt loading were comparable between SHR and WKY.2) We also examined release of atrial natriuretic peptide (ANP) in response to atrail stretch in vitro. We found, first, that ANP release decreased gradually with time despite that an increase in resting tension was maintained, Which suggests that adaptation occures in ANP release in response to atrial stretch. Second, we found that ANP release did not occure when the atria were stretched in the medium with diltiazem <10^(-5)> M or the calciums-free medium. However, repetitive stretch at a frequency of 300 beats/min increased ANP release despite the presence of diltiazem <10^(-5)> M. These results indicate that active muscle contraction or calcium entry into myocytes is not prerequisite for ANP release.