Mechanisms of Na and Ca Transport Across the Plasma Membrane of Squid Giant Axons

Na/Ca交换是一种膜结合机制，负责从细胞中排出净钙。钠/钙交换的重要性是显而易见的，因为它能够挤出大量的钙负荷；然而，这个系统的另一个基本方面是，在某些条件下，它具有“反向”工作的能力，促进了净钙获得和电离ı钙水平的相应增加。在牢房里。这一功能既与生理相关，也与病理相关，因为细胞内钙浓度调节心肌收缩和动脉肌肉收缩。因此，对Na/Ca交换功能的了解有助于深入了解高血压的发生发展机制。本工作旨在进一步表征Na/Ca交换器与载体的不对称性质(对细胞内和细胞外配体的不同反应能力)的关系。目的是确定这种不对称性是系统固有的，还是细胞内和细胞外相周围不同的离子和电环境的结果。这一分析将允许在完整细胞和分离质膜的膜泡中获得的数据之间进行比较，从而拓宽细胞和分子研究的领域。

The Na/Ca exchange is a membrane bound mechanism responsible for net Ca extrusion from the cells. The importance of the Na/Ca exchange is evident from its ability to extrude large Ca loads; however, an additional fundamental aspect of this system results from its capacity, under certain conditions, to work in "reverse" facilitating the net Ca gain and the corresponding increase in the levels of ionized ıCa! of the cell. The relevance of this function is both physiological and pathological, for the intracellular Ca concentrations regulate cardiac muscle contraction and the contraction of the arterial musculature. Therefore, the understanding of the Na/Ca exchange function can provide insights into the mechanisms leading to the development of hypertension. The present work intends to further characterize the Na/Ca exchanger in relation to the asymmetric properties of the carrier (different reactivity towards intra- and extracellular ligands). The aim is to establish if that asymmetry is intrinsic to the system or a consequence of the different ionic and electrical environments surrounding the intra- and extracellular phases of the cell. This analysis will allow a comparison between data obtained in intact cells and in the membrane vesicles from isolated plasma membranes, widening the field of cellular and molecular research.