SM 191a/192a - Functions of the Renal Tubules I and II Flashcards
Activation of the CaSR [downregulates/upregulates] flow through the Na+/K+/2Cl- cotransporter
Explain
Activation of the CaSR downregulates flow through the Na+/K+/2Cl- cotransporter
This decreases the + to - gradient generated by the cotransporter that pulls Ca2+ into the interstitum, thus reducing the force that drives Ca2+ reabsorption
How is the inner-medullary collecting duct similar to the cortical collecting duct?
How is it different?
- Similar:
- Na+ reabsorption pathway
- K+ secretion pathway
- Na+ reabsorption and K+ secretion are reciprocal
- Water channels responsive to ADH
- Different:
- Medullary has ANP receptor on basolateral membrane; when bound to ANP, inhibits Na+ reabsorption
- Promotes naturesis
- Medullary has Urea transporter on apical membrane; reabsorbs urea, recycled back into the interstitium
- Contributes to high interstitial osmolality
- Medullary has ANP receptor on basolateral membrane; when bound to ANP, inhibits Na+ reabsorption
Competition for which transport protein leads to many drug-drug interactions?
P-gp
In the proximal convoluted tubule
(the primary site of secretion for drugs and drug metabolites)
Where in the kidney tubule does transcellular Ca2+ reabsorption occur?
Through which protein?
Distal covoluted tubule
- Apical
- TRPV5 channel
- Basolateral
- Ca2+/3Na+ exchanger
- Driven by Na+ gradient into the cell
- Ca2+/3Na+ exchanger
What are the effects of aldosterone binding to its cytoplasmic receptor?
Aldoserone/receptor complex is transported to the nucleus
- Acts as a transcription factor
- More Na+/K+ ATPases
- More ENaC (Na+ channels)
- More ROMK (K+ channels)
- -> increased Na+ reabsorption, K+ secretion via…
- Short-term mechanisms
- Increased SGK1 activity -> phosphorylates NEDD-2
- P-NEDD-2 cannot retrieve ENaC from the membrane
- => More ENaC to reabsorb Na+
- Later mechanisms
- Increased surface area of basolateral membranes
- -> Inreased Na+/K+ ATPase activity
- Short-term mechanisms