心钠素前体分子内调控对心肌Na^＋—K^＋—ATP酶的作用

目的：研究利钾尿肽及心钠素前体分子内调控作用对心肌Ｎａ＋Ｋ＋ＡＴＰ酶的作用。方法：将大鼠心肌匀浆后，分别加入利钾尿肽、心钠素以及利钾尿肽＋心钠素，用比色法测定Ｎａ＋Ｋ＋ＡＴＰ酶活性。将大鼠心脏悬挂于Ｌａｎｇｅｎｄｏｒｆ灌流装置，分别以利钾尿肽、心钠素、利钾尿肽＋心钠素为灌流液，灌注心脏，用四道生理仪观测左心室内压、左心室收缩最大速率，左心室舒张最大速率，心率及冠脉流量。结果：心钠素虽然对Ｎａ＋Ｋ＋ＡＴＰ酶有抑制作用（抑制率２６．２％），但是，与对照无显著性差异（Ｐ＞０．０５）。利钾尿肽显著抑制酶的活性（抑制率４６．５％，Ｐ＜０．０１）这种抑制作用可被心钠素抵消（抑制率１７．６％，Ｐ＞０．０５）。利钾尿肽可以增加左心室收缩和舒张最大速率以及左室内压，而这种强心作用可因心钠素的加入而消失或减弱。结论：利钾尿肽可以抑制心肌Ｎａ＋Ｋ＋ＡＴＰ酶的活性，产生强心作用，心钠素可以抵消以上作用。

ROLE OF INTRAMOLECULAR REGULATION OF ATRIAL NATRIURETIC FACTORS PROHORMONE IN Na K ATPase OF MYOCARDIUM

Aim: To study the role of kaliuretic peptide (KP) and intramolecular regulation of atrial natriuretic factors prohormone in Na K ATPase of myocardium. Methods: After homogenation, the myocardium of rats was divided into 3 groups and treated with KP, atrial natriuretic peptide (ANP) and KP plus ANP respectively. The activity of Na K ATPase was determined by coloremetry. The hearts of rats were hung on the Langendorff perfusing apparatus and perfused with KP, ANP, KP ANP respectively. Left ventricle press (LVP), maximal systolic and diastolic velocity of left ventricle, heart rate and coronary flow were observed by 4 leadphy siologic analyzeer. Results: ANP had inhibitory effect on Na K ATPase, inhibition rate (IR) was 26.2%, but not significantly (P>0.05). KP inhibited the activity of the enzyme (IR was 46.5%, P<0.01) and the effect could be retarded by ANP(IR was 17.6%, P>0.05). KP could increase the maximal systolic and diastolic velocity of the left ventricle and LVP and this effect would disappear or attenuate with ANP. Conclusion: KP can inhibit myocardial Na K ATPase activity and produce cardiotonic effect, which can be offseted by ANP.