Mathematical simulation of gas transport and acid/base regulation by blood flowing in microvessels--the Cl-/HCO3-exchange across the red cell membrane.
Mathematical simulation of gas transport and acid/base regulation by blood flowing in microvessels--the Cl-/HCO3-exchange across the red cell membrane.
复制标题
对微血管中血液流动的气体运输和酸/碱调节（红细胞膜上的 Cl-/HCO3-交换）进行数学模拟。
DOI：
10.1007/978-1-4615-2468-7_22
复制
发表时间：
1994
影响因子：
--
通讯作者：
Olson,JS
中科院分区：
文献类型：
--
作者：
Huang,NS;Hellums,JD;Olson,JS
Prior workers have often treated the exchange of HCO3−and C1−by use of phenomenological permeability coefficients(1–4).However, discrepancies of several orders of magnitude between the Cl−permeability as measured by isotope exchange and by net (or conductive) flow with direct electrical measurements practically ruled out the possibility that anions as such diffuse across the membrane(5). Those data and other experimental evidence suggest that the exchange mechanism is carrier-mediated; the carrier is capable of one-for one exchange of anions, but does not permit the net flow of anions across the membrane. As a result, the permeability values are only “effective” and must be interpreted accordingly. Therefore, in this work, we studied a mediated-transport system. Most of the experimental evidence on the exchange kinetics point toward the single-site “ping-pong” mechanism with obligatory exchange(5–11)The general features of the ping-pong mechanism are illustrated in Figure 1. In the ping-pong mechanism, the anions take turns crossing the membrane rather than switching place simultaneously; and the protein has two structurally distinct states, an inward-facing state and an outward-facing state. Thus, it is an alternating site transporter possessing a single transport site which is alternatively exposed to the opposite sides of the membrane. This site can only cross the membrane when it is occupied by a substrate anion; it then undergoes a conformational change to face the opposite side of the membrane and releases the transported ion. The transported site can now bind another (or the same) anion and return to the original membrane face, release the anion to complete a cycle of anion exchange.
