Final answer:
The function of the Na+ K+ 2Cl- symporter in the ascending loop of Henle is influenced by ionic gradients created by Na+/K+ ATPase pumps and can be affected by diuretics and hormonal regulation.
Step-by-step explanation:
The Na+ K+ 2Cl- symporter in the ascending nephron loop is an important part of renal physiology and urinary concentration mechanism. This symporter is affected mainly by the ionic gradients established by the Na+/K+ ATPase pumps in the basolateral membrane of the nephron cells, which actively transport Na+ out of the cell, creating a concentration gradient for Na+ to enter the cell on the apical side via the Na+ K+ 2Cl- symporter. The action of this symporter contributes to the countercurrent multiplier system of the loop of Henle that generates high medullary osmolality, essential for water reabsorption.
Factors that can influence the function of the Na+ K+ 2Cl- symporter include the presence of diuretics like furosemide, which inhibit the symporter's activity, and various hormonal controls such as aldosterone, which can indirectly affect symporter activity through alterations in K+ and Na+ handling in other parts of the nephron.