The human leucocyte sodium pump in adrenocortical insufficiency

Area of Science:

• Endocrinology
• Cellular Physiology
• Mineralocorticoid Research

Background:

• Cortisol and related compounds influence sodium balance.
• Adrenocortical insufficiency presents with hormonal deficiencies affecting electrolyte homeostasis.

Purpose of the Study:

• To investigate leukocyte sodium efflux and intracellular electrolyte content in patients with adrenocortical insufficiency.
• To determine the effect of glucocorticoid replacement therapy on cellular sodium balance.

Main Methods:

• Measurement of ouabain-sensitive 22Na+ efflux rate constant in leukocytes.
• Quantification of intracellular sodium and potassium content.
• In vitro incubation of normal leukocytes with dexamethasone.

Main Results:

• Patients with secondary hypoadrenalism exhibited reduced sodium pump activity (lower 22Na+ efflux rate constant).
• Hypoadrenalism was associated with increased intracellular sodium and decreased intracellular potassium-to-sodium ratios.
• Replacement therapy with cortisol, prednisolone, or dexamethasone corrected these cellular defects.
• In vitro dexamethasone increased Na+/K+-ATPase activity in normal leukocytes.

Conclusions:

• Glucocorticoid deficiency impairs cellular sodium balance by affecting sodium pump activity.
• Glucocorticoids play a crucial role in regulating intracellular sodium and potassium levels.
• The effects of cortisol on sodium distribution may be mediated via the Na+/K+-ATPase pump.