Mechanisms of sodium balance: total body sodium, surrogate variables, and renal sodium excretion

摘要

The present focus areas include uneven, nonosmotic distribution of increments in TBS primarily in "skin," long-term instability of TBS dining constant Na~+ intake, and physiological regulation of renal Na~+ excretion primarily by neurohumoral mechanisms dependent on ECV rather than arterial pressure. Under physiological conditions the nonosmotic distribution of Na~+ seems conceptually important, but quantitatively ill defined long-term variations in TBS represent significant deviations from steady state, but the importance is undetermined; and the neurohumoral mechanisms of sodium homeostasis competing with pressure natriuresis are essential for systematic analysis of short-term and long-term regulation of TBS. Sodium homeostasis and blood pressure regulation are intimately related. Real progress is slow and will accelerate only through recognition of the present level of ignorance. Nonosmotic distribution of sodium, pressure natriuresis, and volume-mediated regulation of renal sodium excretion are essential intertwined concepts in need of clear definitions, conscious models, and future attention.