How are the mechanisms of action of frusemide and losartan in treating hypertension different?

Answer 1

Frusemide is a loop diruetic. It prevents the reabsorption of NaCl at the ascending limb of the loop of Henle. Less sodium will result in less water in retained in the body so the blood volume decreases. Although the mechanisms of diruetics is not exactly known, it is believed that it causes a reduction in blood volume which leads to decreased blood pressure. It is also believed that reducing the amount of Na+ in the body leads to a reduction of intracellular Ca2+, resulting in the muscles being less receptive to endogenous vasoconstrictors.

Losartan is an angiotensin receptor blocker. It blocks the angiotensin I receptor. This leads to less angiotensin II being produced. Angiotensin II itself is a vasodilator and it can also cause aldosterone and the antidiruetic hormone to be released. Both aldosterone and the antidiruetic hormone leads to the kidney to retain salt and this leads to more water being retained in the body resulting in a greater blood volume and a greater blood pressure. As Losartan inhibits angiotensin I receptors, it can prevent the release of angiotensin II and hence these effects.