The solubility of calcite and aragonite in seawater at various salinities, temperatures, and one atmosphere total pressure

作者：Alfonso Mucci · 发表于：American Journal of Science · 年份：1983 · DOI：10.2475/ajs.283.7.780 · 被引用次数：1178 · 研究领域：Ion channel regulation and function、Ion Transport and Channel Regulation、Nitric Oxide and Endothelin Effects

We have previously identified the suramin analog 4,4′,4″,4″′-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis-benzene-1,3-disulfonic acid (NF449) as a low nanomolar potency antagonist of recombinant P2X1 receptors. Here, we characterize, by two-electrode voltage-clamp electrophysiology, three isomeric suramin analogs designated para-4,4′,4″,4″″-(carbonylbis(imino-5,1,3-benzenetriylbis (carbonylimino)))tetrakis-benzenesulfonic acid (NF110), meta-(3,3′,3″,3″″-(carbonylbis(imino-5,1,3-benzenetriylbis (carbonylimino)))tetra-kis-benzenesulfonic acid (NF448), and ortho-(2,2′,2″,2″″-(carbonylbis(imino-5,1,3-benzenetriylbis (carbonylimino)))tetra-kis-benzenesulfonic acid (MK3) with respect to their potency in antagonizing rat P2X receptor-mediated inward currents in Xenopus laevis oocytes. Meta, para, and ortho refer to the position of the single sulfonic acid group relative to the amide bond linking the four symmetrically oriented benzenesulfonic acid moieties to the central, invariant suramin core. NF448, NF110, and MK3 were >200-fold less potent in blocking P2X1 receptors than NF449, from which they differ structurally only by having one instead of two sulfonic acid residues per benzene ring. Although the meta- and ortho-isomers retained P2X1 receptor selectivity, the para-isomer NF110 exhibited a significantly increased activity at P2X3 receptors (Ki ∼ 36 nM) and displayed the following unique selectivity profile among suramin derivatives: P2X2+3 = P2X3 > P2X1 > ...