MORECULAR PHARMACOLOGICAL STUDY OF SIGNAL TRANSDUCTION

内皮素（ET）和血管紧张素II （Ang II）激活引发的信号转导过程在许多心血管疾病，即充血性心力衰竭中起着至关重要的作用，在基因表达水平上对心肌细胞功能和疾病进展进行病理生理调节。α-肾上腺素受体的激活共享这些受体触发的信号转导。它们可能调节心脏肥厚和重塑的过程。因此，研究这类受体激活后的信号转导对了解心脏疾病的病理生理和制定治疗策略具有极其重要的意义。虽然由二酰基甘油（DAG）诱导的蛋白激酶C （PKC）的激活可能主要参与调节，但激活PKC和PKC抑制剂的酚酯，如calphostin C和chel…更多的红氨酸，在完整的心肌细胞中不能模仿受体刺激的调节作用。本研究旨在阐明信号转导，即PI水解，在完整心肌和肌细胞中调节心肌收缩力的作用。ET-1和Ang II引起细胞内Ca^<2+>动员增加和肌丝Ca^<2+>敏感性增加。据推测，PKC的激活和随后的Na^+/H^+交换剂的激活导致细胞内碱化和细胞内Ca^<2+ b>离子的继发性增加可能起着至关重要的作用，但由于缺乏药物工具，在完整心肌中缺乏具有足够高选择性的离子交换抑制剂，因此尚未获得令人信服的证据。在本研究中，明确了Na^+/H^+交换剂HOE642和KB-R9032的选择性抑制剂抑制ET-1的正性肌力作用（缩短的增加），而不影响异proterenol在负载indo-1的家兔单肌细胞中的作用。另一方面，Na^+/Ca^<2+>抑制剂KB-R7943可以抑制ET-1诱导的Ca^<2+>瞬态的增加。利用全细胞膜片钳法在兔肌细胞中发现ET-1对l型Ca^<2+>电流的影响不明显。用angii也得到了类似的结果。这些结果表明，ET-1和Ang II受体激活介导的离子交换器刺激在完整心肌细胞Ca^<2+>信号的调控中起着至关重要的作用。少

Signal transduction processes triggered by activation of endothelin (ET) and angiotensin II (Ang II) play a crucial role in a number of cardiovascular diseases, namely in congestive heart failure, for the pathophysiological regulation of myocardial cell function and progression of the disease at the level of gene expression. Activation of α-adrenoceptors shares signal transduction triggered by these receptors. They may regulate the process of cardiac hypertrophy and remodeling. Therefore the study on the signal transduction subsequent to activation of these classes of receptor is of extreme importance for understanding of pathophysiology of cardiac diseases and for constitution of therapeutic strategies. Although activation of protein kinase C (PKC) induced by diacylglycerol (DAG), the product of stimulation of PI hydrolysis resulting from receptor activation, may be primarily involved in the regulation, phorbol esters that activate PKC and PKC inhibitors, such as calphostin C and chel … More erythrine, do not mimic the regulatory effect of receptor stimulation in intact myocardial cells.The study was carried out to elucidate the role of signal transduction, namely PI hydrolysis, in regulation of myocardial contractility in intact myocardium and myocytes. ET-1 and Ang II elicit an increase in intracellular Ca^<2+> mobilization and an increase in myofilament Ca^<2+> sensitivity. It has been postulated that the activation of PKC and subsequent activation of Na^+/H^+ exchanger that leads to intracellular alkalinization and secondary increase in intracellular Ca^<2+> ions may play a crucial role, but compelling pieces of evidence have not yet been obtained because of lack of pharmacological tools, ion exchange inhibitors, with sufficiently high selectivity, in intact myocardium.In the present study, it was clarified that selective inhibitors of Na^+/H^+ exchanger HOE642 and KB-R9032 inhibited the positive inotropic effect (the increase in shortening) of ET-1 without affecting the effect of isoproterenol in rabbit single myocytes loaded with indo-1. On the other hand, the increase in Ca^<2+> transients induced by ET-1 was inhibited by the Na^+/Ca^<2+> inhibitor KB-R7943. It became evident that ET-1 did not cause a prominent effect on L-type Ca^<2+> current by means of whole cell patch clamp in rabbit myocytes. Similar results have been obtained also with Ang II. These results indicate that stimulation of ion exchangers mediated by receptor activation with ET-1 and Ang II plays a crucial role in regulation of Ca^<2+> signaling in intact myocardial cells. Less