Physiology
It is partly responsible for the regulation of potassium, sodium, calcium, and pH. It is the primary site for the kidneys' hormone based regulation of calcium (Ca).
On its apical surface (lumen side), cells of the DCT have a thiazide-sensitive Na-Cl cotransporter and are permeable to Ca, via TRPV5 channel. On the basolateral surface (blood) there is an ATP dependent Na/K antiport pump, a secondary active Na/Ca transporter-- antiport, and an ATP dependent Ca transporter. The basolateral ATP dependent Na/K pump produces the gradient for Na to be absorbed from the apical surface via the Na/Cl synport and for Ca to be reclaimed into the blood by the Na/Ca basolateral antiport.
- It regulates pH by absorbing bicarbonate and secreting protons (H+) into the filtrate, or by absorbing protons and secreting bicarbonate into the filtrate.
- Sodium and potassium levels are controlled by secreting K+ and absorbing Na+. Sodium absorption by the distal tubule is mediated by the hormone aldosterone. Aldosterone increases sodium reabsorption. Sodium and chloride (salt) reabsorption is also mediated by a group of kinases called WNK kinases. There are 4 different WNK kinases, WNK1, WNK2, WNK3, and WNK4.
- It also participates in calcium regulation by reabsorbing Ca2+ in response to parathyroid hormone. PTH effect is mediated through phosphorylation of regulatory proteins and enhancing the synthesis of all transporters within the distal convoluted tubule.
- Arginine vasopressin receptor 2 is also expressed in the DCT.
Read more about this topic: Distal Convoluted Tubule
Famous quotes containing the word physiology:
“A physician’s physiology has much the same relation to his power of healing as a cleric’s divinity has to his power of influencing conduct.”
—Samuel Butler (1835–1902)
“I have more in common with a Mexican man than with a white woman.... This opinion ... chagrins women who sincerely believe our female physiology unequivocally binds all women throughout the world, despite the compounded social prejudices that daily affect us all in different ways. Although women everywhere experience life differently from men everywhere, white women are members of a race that has proclaimed itself globally superior for hundreds of years.”
—Ana Castillo (b. 1953)
“If church prelates, past or present, had even an inkling of physiology they’d realise that what they term this inner ugliness creates and nourishes the hearing ear, the seeing eye, the active mind, and energetic body of man and woman, in the same way that dirt and dung at the roots give the plant its delicate leaves and the full-blown rose.”
—Sean O’Casey (1884–1964)