Volumes and Na+/H+ antiporter activity of lymphocytes in patients with congestive heart failure

Area of Science:

• Cardiology
• Cell Biology
• Pharmacology

Background:

• Congestive heart failure (CHF) is associated with skeletal muscle abnormalities, including altered cellular volume and electrolytes.
• These cellular changes may contribute to peripheral vascular resistance dysregulation and clinical symptoms like muscular weakness in CHF.
• Previous treatments like diuretics and digoxin have been linked to these cellular abnormalities.

Purpose of the Study:

• To investigate the impact of angiotensin-converting enzyme (ACE) inhibitor therapy on cell volume and its regulation in CHF patients.
• To compare cell volume regulation in CHF patients treated with ACE inhibitors versus those on diuretics alone.
• To assess potential structural versus functional changes in cell volume regulation.

Main Methods:

• Measured electronic cell diameters of human mononuclear leukocytes (HML) using a Coulter Counter.
• Compared HML from CHF patients on ACE inhibitors (n=19) with those on diuretics (n=16) and normal volunteers (n=20).
• Assessed Na+/H+ antiporter activity via cell swelling in isotonic propionate, sensitive to ethylisopropylamiloride.

Main Results:

• HML diameters were significantly increased in both CHF patient groups compared to normal controls (P < 0.01 for ACE inhibitors, P < 0.05 for diuretics).
• No significant correlation was found between ejection fraction or digoxin therapy and average cell diameters.
• Ethylisopropylamiloride-sensitive swelling rates were normal in both patient groups, indicating normal Na+/H+ antiporter activity.

Conclusions:

• Increased HML size in CHF patients represents a structural cellular change, not a rapidly reversible functional abnormality.
• Neither ACE inhibitor therapy nor diuretic therapy significantly altered this increased cell size.
• Cell volume regulation, specifically Na+/H+ antiporter activity, appears preserved despite structural changes in HML.