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A mathematical model of acid-base balance and ion transport for mammalian brain tissue and differential effects of cerebrospinal fluid composition on the control of ventilation.

机译：哺乳动物脑组织酸碱平衡和离子迁移的数学模型，以及脑脊液成分对通气控制的不同影响。

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摘要

A model describing acid-base balance and ion transport in a nucleated mammalian cell and its associated extracellular fluid (ECF) was developed from simple biophysical concepts. The model predicts intracellular fluid (ICF) electrolyte concentrations, pH and membrane potential. Three versions of the model were constructed: in two versions, the ECF concentrations are set by the modeler before ICF variables are solved for. These versions are termed the in vitro and in vitro/Donnan models, as they most closely resemble a cell being perfused with artificial ECF. In the in vitro/Donnan model, HCO{dollar}sb3sp-{dollar} distribution is governed by a Donnan equilibrium. While the in vitro/Donnan model predicts non physiological values of ICF pH and K{dollar}sp+{dollar}, it responds to acid-base disturbances in a manner similar to actual cells. The in vitro model predicts physiological values of intracellular pH and K{dollar}sb+{dollar}, but fails to adequately describe acid-base behavior. A third version was constructed in which the ECF and ICF concentrations could be solved for simultaneously, permitting interaction between the two compartments. This model predicted physiological values for ECF ions and pH, and for ICF pH and K{dollar}sp+{dollar}, but not for ICF Na{dollar}sp+{dollar} and Cl{dollar}sp-{dollar}.; Experiments were performed in which the effects of cerebrospinal fluid (CSF) pH versus ionic composition on central respiratory chemosensitivity could be differentiated. It was established that perfusions over the ventral surface of the brain with acidic mock CSF solutions caused significant increases in both tidal volume (V{dollar}sb{lcub}rm T{rcub}{dollar}) and minute ventilation (V{dollar}sb{lcub}rm E{rcub}{dollar}). When some of the chloride in the acidic perfusate was replaced with the impermeant anion isethionate there were greater increases (p = 0.05) in both V{dollar}sb{lcub}rm T{rcub}{dollar} and V{dollar}sb{lcub}rm E{rcub}{dollar} at an identical pH. The PCO{dollar}sb2{dollar} of the fluid perfusing the brain was held constant. These findings suggest that the two acidic perfusates exert different effects on ECF H{dollar}sp+{dollar}, the putative stimulus for the chemoreceptors. When HCO{dollar}sb3sp-{dollar}/Cl{dollar}sp-{dollar} exchange was blocked with an anion transport inhibitor, the difference in V{dollar}sb{lcub}rm T{rcub}{dollar} between the two acidic perfusates was abolished, suggesting a role for this exchanger in determining central chemoreceptor input.
机译：从简单的生物物理概念发展了一个模型，该模型描述了有核哺乳动物细胞及其相关的细胞外液（ECF）中的酸碱平衡和离子运输。该模型预测细胞内液（ICF）的电解质浓度，pH和膜电位。构建了模型的三个版本：在两个版本中，建模者在求解ICF变量之前设置ECF浓度。这些版本被称为“体外”和“体外/唐南模型”，因为它们最类似于被人工ECF灌注的细胞。在体外/唐南模型中，HCO {dollar} sb3sp- {dollar}的分布受Donnan平衡支配。尽管体外/唐南模型预测了ICF pH和K {dollar} sp + {dollar}的非生理值，但它以类似于实际细胞的方式对酸碱紊乱做出了反应。体外模型可预测细胞内pH和K {dollar} sb + {dollar}的生理值，但无法充分描述酸碱行为。构造了第三种形式，其中可以同时解决ECF和ICF浓度问题，从而允许两个部分之间的相互作用。该模型预测了ECF离子和pH以及ICF pH和K {dollar} sp + {dollar}的生理值，但未预测ICF Na {dollar} sp + {dollar}和Cl {dollar} sp- {dollar}的生理值。进行了实验，可以区分脑脊液（CSF）pH与离子组成对中枢呼吸道化学敏感性的影响。已经确定，用酸性模拟CSF溶液灌注脑腹面会导致潮气量（V {dollar} sb {lcub} rm T {rcub} {dollar}）和通气量（V {dollar} sb {lcub} rm E {rcub} {dollar}）。当酸性灌流液中的某些氯化物用不渗透的阴离子羟乙磺酸盐替代时，V {dollar} sb {lcub} rm T {rcub} {dollar}和V {dollar} sb {在相同pH值下的lcub} rm E {rcub} {dollar}。灌注到大脑的液体的PCO {dollar} sb2 {dollar}保持恒定。这些发现表明，两种酸性灌流液对ECF H {dollar} sp + {dollar}（化学感受器的假定刺激）发挥不同的作用。当HCO {dollar} sb3sp- {dollar} / Cl {dollar} sp- {dollar}的交换被阴离子转运抑制剂阻止时，两者之间V {dollar} sb {lcub} rm T {rcub} {dollar}的差异取消了两种酸性灌注液，表明该交换剂在确定中央化学感受器输入中的作用。

著录项

  • 作者

    Davidson, Teresa Lynn.;

  • 作者单位

    University of Virginia.;

  • 授予单位 University of Virginia.;
  • 学科 Biology Animal Physiology.; Engineering Biomedical.; Biophysics Medical.
  • 学位 Ph.D.
  • 年度 1989
  • 页码 138 p.
  • 总页数 138
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生理学;生物医学工程;生物物理学;
  • 关键词

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