Effect of hydrogen ion concentration on corticosteroid secretion

Area of Science:

• Endocrinology
• Physiology
• Acid-Base Balance

Background:

• Corticosteroid secretion is regulated by various factors, including adrenocorticotropic hormone (ACTH).
• The direct influence of acid-base balance on adrenal steroidogenesis is not fully understood.
• Understanding these mechanisms is crucial for managing endocrine and metabolic disorders.

Purpose of the Study:

• To investigate the direct effects of extracellular hydrogen ion (H+) concentration on corticosteroid secretion.
• To determine how changes in acid-base balance influence basal and ACTH-stimulated hormone release from the canine adrenal gland.

Main Methods:

• Isolated, perfused canine adrenal glands were used to control perfusate composition.
• Extracellular H+ concentration was manipulated by altering partial pressure of carbon dioxide (PCO2) or bicarbonate ([HCO3-]) levels.
• Secretion of aldosterone, corticosterone, 18-hydroxycorticosterone, and cortisol was measured under basal and ACTH-stimulated conditions.

Main Results:

• Alkalosis significantly inhibited ACTH-stimulated aldosterone secretion.
• A positive correlation was observed between H+ concentration and aldosterone secretion, but a negative correlation with corticosterone and 18-hydroxycorticosterone secretion in response to ACTH (pH range 7.19-7.85).
• Neither acidosis nor alkalosis directly affected basal or ACTH-stimulated cortisol secretion.

Conclusions:

• Extracellular H+ concentration directly modulates ACTH's effect on aldosterone secretion via the adrenal cortex.
• Acid-base disturbances specifically impact the zona glomerulosa in canine adrenal glands.
• H+ concentration may influence late stages of aldosterone biosynthesis.