Graves J S, Gutknecht J
J Gen Physiol. 1976 May;67(5):579-97. doi: 10.1085/jgp.67.5.579.
Using cultured cells of the marine alga, Halicystis parvula, we measured the concentrations of 11 inorganic ions in the vacuolar sap and the electrical potential difference (PD) between the vacuole and the external solution. In normal cells under steady-state conditions a comparison of the electrochemical equilibrium (Nernst) potential for each ion with the PD of -82 mV (inside negative) indicates that Na+ and K+ are actively transported out of the vacuole whereas all anions are pumped into the cell. Although the [K+] in the vacuole is only 9 mM, the cytoplasmic [K+] is about 420 mM, which suggests that the outwardly directed pump is at the tonoplast. Using large Halicystis cells we perfused the vacuole with an artificial seawater and conducted a short-circuit analysis of ion transport. The short-circuit current (SCC) of 299 peq - cm-2-s-1 is not significantly different from the net influx of Cl-. There is a small, but statistically significant net efflux of K+ (less than 1 pmol-cm-2.-1), while the influx and efflux of Na+ are not significantly different. Therefore, the SCC is a good measure of the activity of the Cl- pump. Finally, we measured the volumetric elastic modulus (epsilon) of the cell wall by measuring the change in cell volume when the internal hydrostatic pressure was altered. The value of epsilon at applied pressures between 0 and 0.4 atm is about 0.6 atm, which is at least 100-fold lower than the values of epsilon for all other algae which have been studied.
我们使用海洋藻类小海囊藻（Halicystis parvula）的培养细胞，测量了液泡液中11种无机离子的浓度以及液泡与外部溶液之间的电势差（PD）。在稳态条件下的正常细胞中，将每种离子的电化学平衡（能斯特）电势与-82 mV（内部为负）的PD进行比较表明，Na⁺和K⁺被主动转运出液泡，而所有阴离子被泵入细胞。尽管液泡中的[K⁺]仅为9 mM，但细胞质中的[K⁺]约为420 mM，这表明向外的泵位于液泡膜上。我们使用大型小海囊藻细胞，用人工海水灌注液泡，并对离子转运进行短路分析。299 peq·cm⁻²·s⁻¹的短路电流（SCC）与Cl⁻的净内流没有显著差异。有少量但在统计学上显著的K⁺净外流（小于1 pmol·cm⁻²·s⁻¹），而Na⁺的内流和外流没有显著差异。因此，SCC是Cl⁻泵活性的良好指标。最后，我们通过测量内部静水压力改变时细胞体积的变化来测量细胞壁的体积弹性模量（ε）。在0至0.4 atm的施加压力下，ε的值约为0.6 atm，这比所有其他已研究藻类的ε值至少低100倍。
