Equations for O2 and CO2 solubilities in saline and plasma: combining temperature and density dependences

Solubilities of respiratory gasses in water, saline, and plasma decrease with rising temperatures and solute concentrations. Henry’s Law, C = α·P, states that the equilibrium concentration of a dissolved gas is solubility times partial pressure. Solubilities in the water of a solution depend on temperature and the content of other solutes. Blood temperatures may differ more than 20°C between skin and heart, and an erythrocyte will undergo that range as blood circulates. The concentrations of O2 and CO2 are the driving forces for diffusion, exchanges, and for reactions. We provide an equation for O2 and CO2 solubilities, α, that allows for continuous changes in temperature, T, and solution density, , in dynamically changing states:a(T, sol, , , β)=[1–⋅(sol–)β]⋅(C1⋅e–k1T+C2⋅e–k2T) This two-exponential expression with a density scalar , and a density exponent β, accounts for solubility changes due to density changes of an aqueous solution. It fits experimental data on solubilities in water, saline, and plasma over temperatures from 20 to 40°C, and for plasma densities, sol up to 1.020 g/ml with ~0.3% error. The amounts of additional bound O2 (to Hb) and CO2 (bicarbonate and carbamino) depend on the concentrations in the local water space and the reaction parameters. During exercise, solubility changes are large; both sol and T change rapidly with spatial position and with time. In exercis...
Source: Journal of Applied Physiology - Category: Physiology Authors: Tags: INNOVATIVE METHODOLOGY Source Type: research