【作者】 梁哲龙；

【导师】 崔勋；

【作者基本信息】 延边大学 ， 生理学， 2007， 硕士

【摘要】 高渗、高钾刺激对心房钠尿肽分泌的影响心脏作为内分泌器官，生成和分泌钠尿肽激素（natriuretic peptides）参与调节体液和血压。自从1981年De Bold等首次发现心房钠尿肽（atrial natriuretic peptide，ANP）以来，目前已确认人和动物体内存在钠尿肽家族（family of natriuretic peptide，NPs）激素。它包括四大成员，即ANP、脑钠尿肽（brain natriuretic peptide，BNP）、C型钠尿肽（C-type natriuretic peptide，CNP）和D型钠尿肽（dendroaspis natriureticpeptide，DNP）。这类激素共同的生物学作用是排钠，排尿，参与水盐平衡和血压调节、抑制细胞增殖、调节免疫和保护细胞以及脂质代谢等。尽管早期研究指出，心房血容量增加，心房肌牵张，心率加快和血压升高可刺激心房ANP的分泌。而且除了肾上腺素能、胆碱能及肽能受体对ANP分泌具有一定的调节作用外，内皮素（ET）-1通过其ET-A受体促进ANP的分泌。但ANP分泌的详细机制尚不甚清楚。临床及实验研究证实，高渗的氯化钠溶液可明显增加肾血流量，尿量及肌酐清除率，促进体内代谢尾产物的排泄，改善肾脏功能。其中具有排钠，排水效应的ANP发挥重要作用。而且一些研究表明，高渗刺激促进ANP的分泌，其作用主要受Ca²⁺调节。另外，Chan等在观察34名患有高血钾症的病人中发现，大多数肾素-血管紧张素-醛固酮系统受抑制患者血浆ANP的含量明显增加。这些研究结果表明，高渗、高K⁺对ANP分泌具有调节作用，但其机制尚不清楚。为此，本研究利用放射免疫技术，采用家兔离体搏动的心房灌流模型，观察和探讨高渗、高钾刺激对家兔心房ANP分泌的影响及其作用机制，为阐明和探讨ANP分泌机制及其功能研究提供理论依据。本项研究结果如下：1、不同浓度（30、60、100mmol／L）的甘露醇高渗液明显增加家兔心房ANP的分泌（分别P＜0.01）和心房搏出量（分别P＜0.01），并呈现剂量依赖性特征。但心房搏动压在30mmol／L时开始明显增加（P＜0.01），在60mmol／L时达到峰值（P＜0.01），在100mmol／L下反而呈现下降趋势，但仍高于对照循环（P＜0.01）。甘露醇高渗液对ANP分泌和心房机械活动的上述影响在60mmol／L下达到最佳效应。2、L-型Ca²⁺通道阻断剂nicardipine（1.0μmol／L），可阻断60mmol／L甘露醇高渗液诱导的ANP分泌增多和增加心房每搏出量的效应。而细胞内Ca²⁺库阻断剂ryanodine （1.0μmol／L）尽管阻断甘露醇（60mmol／L）高渗液诱导的心房搏出量增加作用，但未能改变其诱导的ANP分泌增多的效应（P＜0.01）。3、ATP敏感的K⁺通道(K_ATP)阻断剂glibenclamide（1.0μmol／L），未能改变甘露醇（60mmol／L）高渗液诱导的ANP分泌增多（P＜0.001）效应，但可阻断高渗引起的心房每搏出量增加作用（P＞0.05）。4、高K⁺缓冲液（120％K⁺ of HEPES buffer）明显增加家兔心房ANP的分泌（P＜0.01），但对心房每博输出量没有引起显著影响（P＞0.05）。5、ATP敏感的K⁺ (K_ATP)通道阻断剂glibenclamide （1.0μmol／L），能够阻断高钾诱导的ANP分泌增加效应（P＞0.05），而对心房播出量未能引起明显影响；电压门控的K⁺通道阻断剂TEA （tetraethylammonium chloride，TEA）抑制心房搏出量（P＜0.05）的同时也可阻断高K⁺诱导的ANP分泌增多效应（P＞0.05）。6、L-型Ca²⁺通道阻断剂nicardipine（1.0μmol／L），明显抑制心房搏出量（P＜0.01）的同时阻断高K⁺诱导的ANP分泌增多效应。以上结果提示：1、高渗、高K⁺刺激均促进家兔心房ANP的分泌。2、高渗刺激促进心房ANP分泌的作用与L-型Ca²⁺通道有关。3、高K⁺刺激引起心房ANP分泌增多的效应与ATP敏感的和电压门控的K⁺通道有关，且L-Ca²⁺型通道也在参与调节。更多还原

【Abstract】 Effects of hypertonic and hyperkalemic solution of ANP secretion in beating rabbit atriaAs an endocrine gland, the heart generating and secreting natriuretic peptides （NPs） and participate in regulating body fluid and blood pressure. Since 1981 De Bold et al discovered atrial natriuretic peptide （ANP） in the atria, there are four members in NPs including ANP, BNP （brain natriuretic peptide, BNP）, CNP （C-type natriuretic peptide, CNP） and DNP （dendroaspis natriuretic peptide, DNP）. It was known that all of the NPs members incorporate a seventeen-residue intra-molecular disulfide loop of amino acids and involved in vasorelaxation, decreasing blood pressure, diuresis and natriuresis, inhibition of cellular proliferation, regulating immunization, protecting cell and lipolysis by combining with natriuretic peptide receptor which is stored in heart, blood vessel, central nervous system, lymph tissue, reproductive organs and kidney.Previous studies shown that rising atrial blood volume, stretching atrial myocytes, accelerating heart rate or rising blood pressure may increasing atrial ANP secretion and adrenergic, cholinergic and peptidic receptors were involved in regulating atrial secretion of ANP. Furthermore, （ET）-1 which can promote to ANP secretion via the receptor of ET-A is regarded to be the most important factor that regulates atrial ANP secretion.Clinical and experimental data shown that hypertonic solution （NaCl） obviously increased renal blood flow, urine volume and creatinine and promoted to excreting of internal metabolites and improved nephric function while it was demonstrated that ANP led a principal roles in it. In addition, some experiments suggested that hyperosmolality promoted ANP secretion mainly by Ca2⁺ regulation. Chan et al discovered that the most patients with an inhibition of renin-aldosterone system （SAS） showed high levels of internal ANP release by observing 34 patients with hyperkalemia. However, the mechanism by which hypertonicity and hyperkalemia regulate ANP secretion is not clear. Therefore, the purpose of present study is to define the effects of hypertonicity and hyperkalemia on the regulation of atrial ANP secretion in perfused beating rabbit atria. The results of the present study showed that:1、Perfusion with hypertonic solution, constituted by 30, 60, 100 mmol/L mannitol respectively, significantly increased ANP secretion （all P＜0.01） and the atrial stroke volume （all P＜0.01） by dose-dependent manner. The changes in atrial pulse pressure was also significantly increased at 30 mmol/L mannitol （P＜0.01） and reached the peak at 60 mmol/L mannitol （P＜0.01） and showed decreasing tendency at 100 mmol/L mannitol （but higher than the control levels, P＜0.01 vs control）. The most effects of hypertonic solution on ANP secretion and atrial dynamics were observed at 60 mmol/L minnitol.2、L-type Ca²⁺ channel blocker nicardipine （1.0μmol/L） blocked the effect of hypertonic solution-induced increase of ANP secretion and stroke volume. However, ryanodine （1.0μmol/L）, a blocker of myocytic sarcoplasmic reticulum Ca²⁺ release, failed to modulation of ANP secretion with decreased in atrial stroke volume （P＜0.01）.3、ATP-sensitive potassium channel (K_ATP) blocker glibenclamide （1.0μmol/L） failed to modulation of hypertonic solution-induced increase of ANP secretion with significantly inhibited in atrial stroke volume.4、Hyperkalemic solution （120% K⁺ of HEPES buffer） significantly increased ANP secretion （P＜0.01） without changes in atrial stroke volume （P＞0.05）.5、ATP-sensitive potassium channel blocker glibenclamide （1.0μmol/L） blocked the effect of hyperkalemia-induced increase of ANP secretion without changes in atrial stroke volume. Voltage-dependent potassium channel blocker TEA （tetraethylammonium chloride） also blocked the effect of hyperkalemia-induced increase of ANP secretion with decreased in atrial stroke volume （P＜0.05）.6、L-type Ca²⁺ channel blocker nicardipine （1.0μmol/L） obviously attenuated the effect of hyperkalemic solution-induced increase of ANP secretion with inhibited in atrial stroke volume （P＜0.01）.These results indicate that:1、Hypertonic and hyperkalemic solution stimulated ANP secretion in perfused beating rabbit atria.2、Hypertonic solution-induced increment of ANP secretion via Ca²⁺-dependent signaling pathway.3、ATP sensitive- and voltage-gated K⁺ channel were involved in the regulation of hyperkalemic solution-promoted atrial ANP secretion in perfused beating rabbit atria and L-type Ca²⁺ channel was also involved in it.更多还原