Endocrine Abstracts

Distribution of K+ contrasts with Na+: Na+ is predominantly extracellular (EC) and K+ is intracellular (IC ~98% = ~3,500 mmoles). High IC K+ is needed for regulation of cell volume, pH, enzyme function, DNA/protein synthesis, and growth. Low EC K+ (plasma K+; PK), and the associated steep transmembrane K+ gradient, is largely responsible for the membrane potential difference (p.d.) of excitable and non-excitable cells; any change in the gradient (doubling or halving PK) will d...