ATP pumps and ion exchangers Flashcards
Explain the NCX and role in intracellular Ca concentration. What can this cause? When does this reverse? What can this lead to?
Expels 1 Ca2+ for 3Na+ in so is electrogenic, can initiate depolarisation.
Role in cell toxicity during ischaemia/reperfusion
At depolarised membrane potentials it reverses the mode of operation - toxicity
Why do you find accumulation of Ca2+ in cardiac myocytes post MI?
Due to NCX reversal and accumulation.
Why do cancer cells have increased usage of NHE?
Because the alkalinity it produces is beneficial to growth factors and then further activated by growth factors
Name 4 ion channels/pumps that are involved in pH regulation intracellularly, and name the 3 that are in all/most cells
NaKATPase - sets Na gradient
NHE - NaH+ exchanger - Na in H+ out acid extruder
AE - Anion exchanger Cl- in HCO3- out base extruder
NBC - Na and HCO3 in H and Cl- out
NaHCO3- cotransporter both in
In all/most cells are
NaKATPase, NHE and AE
Name the pumps/channels involved in intracellular calcium control
PMCA NCX SERCA VOCCs Mitochondrial uniport at high Ca2+ levels.
How would you control the cell volume to make a cell shrink/swell? How many molecules of water follow 1 osmotically active ion?
Use channels with osmolytes crossing so water follows either in or out
e. g. NHE
e. g. HCO3- Cl exchanger
no one mechanism - regulated with osmotically active ions - 6 molecules of water for 1 osmotically active ion crossing.
How would you resist cellular swelling?
Equal ions either side to prevent movement of water in.
What channels and ion movements are involved in Na+ reabsorption in the kidney thick ascending, distal convoluted tubule, and cortical collecting duct?
1) Ascending limb (2:3) NKCC2 ROMK vs KClT CIC NaKATPase
2) Distal convoluted tubule (3:4) ROMK ENaC TRPM6 (Mg/Ca) vs NCX ClC NaKATPase ROMK
3) Cortical collecting duct Aquaporins ENaC ROMK (opp way) ClC vs ROMK (opp way) NaKATPase ClC
What does Thiazide do where does it act?
NCCT blocker - hypertension
What does Amiloride do where does it act?
ENaC blocker - hypertension
What does Spironolactone do where does it act?
Blocks on ROMK, ENaC, and NaKATPase to reduce severe hypertension
What do ADH and Aldosterone act on? What two effects does this have on cardiovascular system?
ADH - Aquaporins - increase water reabsorption
Aldosterone - ENaCs, ROMK, NaKATPase
increase Na reabsorption
= increased BP and BVol
What does Frusemide do where does it act?
on NKCC2 loop dieuretic
