Mechanism of Action

Both agents appear to affect Na+ reabsorption in the cortical collecting duct. A site in the connecting tubule also may be involved. Although amiloride has been more extensively studied than triamterene, both diuretics specifically block the apical membrane epithelial Na+ channel (ENaC) (Fig. 21-5).The reduced rate of Na+ reabsorption diminishes the gradient that facilitates K+ secretion. K+ secretion by the collecting duct principal cells is a passive phenomenon that depends on and is secondary to the active reabsorption of Na+.

In addition to their effects on distal Na+ and K+ transport, all of the K+-sparing diuretics inhibit urinary H+ secretion by the late distal tubule and cortical collecting duct. The mechanism of this inhibitory action is not totally clear.

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Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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