Abstract

Rational treatment and thorough diagnostic classification of acid-base disorders requires quantitative understanding of the mechanisms that generate and dissipate loads of acid and base. A natural precondition for this tallying is the ability to quantify the acid content in any specified fluid. Physical chemistry defines the pH-dependent charge on any buffer species, and also on strong ions on which, by definition, the charge is pH-invariant. Based, then, on the requirement of electroneutrality and conservation of mass, it was shown in 1914 that pH can be calculated and understood on the basis of the chemical composition of any fluid. Herein we first show that this specification for [H⁺] of the charge-balance model directly delivers the pH-dependent buffer-capacity as defined in the literature. Next, we show how the notion of acid transport as proposed in experimental physiology can be understood as a change in strong ion difference, ΔSID. Finally, based on Brønsted-Lowry theory we demonstrate that by defining the acid content as titratable acidity, this is equal to SID_ref – SID, where SID_ref is SID at pH 7.4. Thereby, any chemical situation is represented as a curve in a novel diagram with titratable acidity = SID_ref – SID as a function of pH. For any specification of buffer chemistry, therefore, the change in acid content in the fluid is path invariant. Since constituents of SID and titratable acidity are additive, we thereby, based on first principles, have defined a new framework for modeling acid balance across a cell, a whole organ, or the whole-body.

摘要

酸碱失调的合理治疗和彻底诊断分类需要定量了解产生和消散酸碱负荷的机制。这种计数的自然先决条件是能够量化任何指定流体中的酸含量。物理化学定义了任何缓冲物质的 pH 依赖电荷，以及强离子，根据定义，强离子的电荷是 pH 不变的。然后，根据电中性和质量守恒的要求，1914 年表明可以根据任何流体的化学成分计算和理解 pH 值。在这里，我们首先表明 [H ⁺] 的电荷平衡模型直接提供文献中定义的 pH 依赖性缓冲容量。接下来，我们将展示如何将实验生理学中提出的酸转运概念理解为强离子差异 ΔSID 的变化。最后，根据 Brønsted-Lowry 理论，我们证明通过将酸含量定义为可滴定酸度，这等于 SID _ref – SID，其中 SID _ref是 pH 7.4 时的 SID。因此，任何化学情况都表示为新图表中的曲线，其中可滴定酸度 = SID _ref– SID 作为 pH 的函数。因此，对于任何缓冲化学规格，流体中酸含量的变化都是路径不变的。由于 SID 的成分和可滴定酸度是相加的，因此我们根据第一原理定义了一个新的框架，用于模拟细胞、整个器官或全身的酸平衡。