What is the primary function of pressin in pharmacology?

• A. Antidiuretic, reabsorbs water into the kidneys
• B. Increases blood pressure during shock
• C. Acts as a bronchodilator
• D. Decreases anxiety in psychiatric disorders

Answer: (A)

The primary function of pressin, more commonly known as vasopressin or antidiuretic hormone (ADH), is to act as an antidiuretic, promoting the reabsorption of water in the kidneys. When vasopressin is released, it binds to receptors in the renal collecting ducts, leading to increased permeability to water. This results in more water being reabsorbed back into the bloodstream, which helps concentrate the urine and reduce the volume of water excreted by the kidneys. This mechanism is critical in maintaining the body’s fluid balance and regulating blood osmolarity.

The other options relate to various physiological processes but do not accurately describe the primary function of pressin. For example, while vasopressin can influence blood pressure, its principal role is focused on water reabsorption rather than direct blood pressure augmentation. Other compounds are typically more associated with bronchodilation and anxiety reduction, making the choice of vasopressin’s antidiuretic function the most appropriate and accurate answer.