The a subunit has a positively charged Arg side chain that forms an electrostatic interaction with the negatively charged carboxylate of Asp on the adjoining c subunit

TLS Online TPP Program

#Id: 5550

#Unit 7. System Physiology – Animal

The second half of the distal tubule and the subsequent cortical collecting tubule have two distinct cell types:  principal cells and intercalated cells

TLS Online TPP Program

#Id: 5551

#Unit 7. System Physiology – Animal

The principal cells reabsorb sodium and water from the lumen and secrete potassium ions into the lumen

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#Id: 5552

#Unit 7. System Physiology – Animal

The principal cells are the primary sites of action of the potassium-sparing diuretics, including spironolactone, eplerenone, amiloride, and triamterene

TLS Online TPP Program

#Id: 5553

#Unit 7. System Physiology – Animal

Intercalated cells play a major role in acid-base regulation and constitute 30 to 40 percent of the cells in the collecting tubules and collecting ducts

TLS Online TPP Program

#Id: 5554

#Unit 7. System Physiology – Animal

There are two types of intercalated cells: type A and type B

TLS Online TPP Program

#Id: 5555

#Unit 7. System Physiology – Animal

Type A intercalated cells  secrete hydrogen ions by a hydrogen-ATPase transporter and by a hydrogen-potassium-ATPase transporter are especially important in eliminating hydrogen ions while reabsorbing bicarbonate in acidosis