Question: 

Garlic is well known as a natural remedy with beneficial effects against high blood pressure. However, the mechanisms how garlic exerts its hypotensive effects are poorly understood. The regulation of blood pressure in the kidney is linked to transepithelial sodium reabsorption from the primary urine and particularly the activity of epithelial sodium channels (ENaC). Therefore we questioned whether there might be any impact of compounds from garlic on the activity of ENaCs.

Methodology: 

Human ENaCs, consisting of the a, b and g subunits, were heterologously expressed in Xenopus oocytes. Transmembrane currents (I_M) were recorded by the two-electrode voltage-clamp technique. Garlic extract (GE) was made from 5 g of fresh garlic in 10 ml of oocyte ringer solution on ice for 1 hour and further diluted with oocyte ringer.

Results: 

The application of GE led to a dose-dependent decrease of I_M of ENaC expressing oocytes, peaking at 80 % inhibition with the highest concentration (1 % GE). The effect was not apparent on water-injected control oocytes. The decrease of I_M due to GE was not reversible and was fully sensitive to the ENaC inhibitor amiloride.

Conclusion: 

These data indicate that compounds from GE irreversibly inhibit the activity of ENaCs. Decreasing sodium reabsorption in the kidney epithelium might represent a mechanism for diuresis, natriuresis and consequently hypotension as attributed to the beneficial effects of garlic.