What is the primary action of loop of Henle agents?

The primary action of loop of Henle agents, such as loop diuretics, is to block the absorption of sodium and chloride in the ascending limb of the loop of Henle in the nephron. This action leads to an increase in the excretion of water, sodium, and chloride, effectively promoting diuresis (increased urine production). By preventing the reabsorption of these electrolytes, loop diuretics cause the renal tubules to excrete more sodium and water, which is beneficial in the management of conditions like heart failure where fluid retention is a concern.

This mechanism is crucial in reducing blood volume and thus lowering blood pressure and alleviating the symptoms associated with fluid overload. Therefore, while other options may pertain to related physiological responses, none address the primary action of these agents as clearly as the blockage of sodium and chloride absorption does.