- Na/K ATPase
- Alpha and beta subunit
- Alpha
- Coordinate cation transport
- 3Na efflux, 2K influx
- Maintain Na K concentration gradient
- In epithelial cells
- Drive Na and K transport
- In non-epithelial cells
- Determine resting membrane potential
- Allow depolarisation
- Allow electrical signalling
- Bind and hydrolyse ATP to release energy to drive transport
- Drugs targeting Na/K ATPase
- Digoxin
- Increasing cardiac contractility
- Inhibits ATPase enzyme of Na/K ATPase
- Preventing hydrolysis
- Removes energy supply
- Inhibit Na efflux, K influx
- Rise in intracellular Na
- Rise in intracellular Ca
- Enhancing actin-myosin interaction
- Increasing cardiac contractility
- ?Significant inotropic in heart failure treatment
- Enhances vagal activity
- Slow conduction via atrioventricular node
- Used in rate control in atrial fibrillation
CARRIERS THAT UTILISE SECONDARY ACTIVE TRANSPORT MECHANISMS
- Energy from electrochemical gradient of one ion
- Na/K/2Cl cotransporter
- Mediates Na transport across epithelia
- Thick ascending limb of the loop of Henle
- Reabsorption 25% Na
- Drugs targeting Na/K/2Cl co transporter
- Loop diuretics (frusemide)
- Causes natriuresis
- Block Na/K/2 Cl cotransporter
- Reducing Na and K reabsorption
- Disease caused by abnormal Na/K/2Cl co transporter
- Bartter's syndrome
- Rare
- Profound hypokalaemia in infancy
- Na/Cl co-transporter
- Mediates Na transport across epithelia
- Distal tubule
- Reabsorption of 10% Na
- Drugs targeting Na/Cl co-transporters
- Thiazide diuretics
- Causes natriuresis
- Blocks Na/Cl co-transporter
- Reducing Na and Cl reabsorption
- Disease caused by abnormal Na/Cl co-transporters
- Gitelman's syndrome
- Hypokalaemia in adults
No comments:
Post a Comment