Angiotensin Converting Enzyme (ACE)

Key Physiological Role:

• Renin-Angiotensin System (RAS): ACE acts as a key component of the RAS, a system that manages fluid and electrolyte balance.
• Vasoconstriction: By forming angiotensin II, it increases contraction of vascular smooth muscle.
• Aldosterone Stimulation: It triggers the release of aldosterone, which causes the kidneys to retain sodium and water, increasing blood volume and pressure.
• Bradykinin Breakdown: It inactivates bradykinin, a peptide that would otherwise relax blood vessels.

ACE Inhibitors (ACEI):

These medications are commonly used to manage blood pressure and treat conditions like heart failure and kidney disease.

• Mechanism: They reduce the conversion of angiotensin I to angiotensin II, leading to lower blood pressure, decreased vascular resistance, and decreased salt/water retention.
• Examples: Common medications include lisinopril, captopril, enalapril, and ramipril.
• Side Effects: Potential side effects may include a dry cough, high potassium levels (hyperkalemia), and increased creatinine.

Clinical Significance & Testing:

• Sarcoidosis Marker: High serum ACE levels are used to monitor active sarcoidosis, a granulomatous disease.
• Disease Monitoring: Elevated levels can be found in 50–80% of patients with active sarcoidosis, and levels are used to assess treatment response.

ACE and COVID-19:

It is theorized that ACE inhibitors may have a potential role in treating COVID-19 related lung injury. Some research indicates that patients with severe COVID-19 might have higher serum ACE levels, leading to increased risk of lung damage, although more study is needed.

Other Forms:

• Germinal ACE: A specific form found in the testes, crucial for sperm maturation and motility.

Commonly Used ACE Inhibitors:

• Benazepril
• Captopril
• Enalapril
• Lisinopril
• Perindopril
• Ramipril
• Trandolapril
• Zofenopril.