Garden - Patch clamp

Question 1

What are the 5 functional measurements of electrical properties in mammalian cells?

Answer 1

1. resting membrane potential -20mV to -90mV
2. cellular membrane resistance -100MO-1GO
3. membrane capacitance - 10-100pF
4. currents at nerve/muscle synapse
5. single channel conductance

Question 2

Nmae the four steps of the patch clamp technique

Answer 2

• single channel activity
• conductance
• open probability
• voltage and calcium sensitivity

Question 3

explain the three points associated with single channel conductance

Answer 3

• single channel amplitude
• measure lots of openings in the presence of AcH
• gaussian fit to amplitude distrubution

Question 4

what are the four patch clamp technqiues

Answer 4

1. subcellular
2. cellular
3. networks
4. in vivo

Question 5

for patch clamp and voltage and ion selecitivty, list the membrane potential, ionic conditions and ionic slecitivity

Answer 5

membrane potential: 120 mV
ionic conditions: physiological gradient, 5/135 mM KCL, symmetrical. 140/140 mM KCL
ionic selectivity: K»Na or Ca

Question 6

whats the slope conductance for single channel

Answer 6

250 pS

Question 7

what does a gaussian fit reveal

Answer 7

reveals time spent open or closed state

Question 8

name the three points associated with multiple channel recordings and the total current equation

Answer 8

1. you control the ionic conditions
2. you control the membrane voltage
3. if you record mulitple channels of the same type then ..
   Total current = i.Nf.Po
   i = single channel amplitude
   Nf = Number of functional channels
   Po = channel open probability

Question 9

discuss the metabolic regulation of potassium channels in the hypothalamus and the association with rodents

Answer 9

Ventro-Medial Nucleus (VMN) and the lateral hypothalamic area (LH)
1. the roden VMN
2. glucose sensing neurons with KATP channels like betal cells
3. obese rats show dysfunctional responses

Question 10

what are the in vivo classification of VMNH neurons

Answer 10

1. 9-sub populations
2. constructed from extracellular recordings of single cells in vivo
3. of the 271 cells recorded 90% could be classified in one of the 9 subpopulations

Question 11

what are some problems for in-vivo

Answer 11

1. approach
2. whole cell configuration
3. behaviour
4. loss of seal

Question 12

what are the post-translational modifications of potassium channels

Answer 12

1. BKCa channels and neuroscience
2. function and dysfunction
3. splice variants
4. phosphorylation
5. palmitoylation

Question 13

what is BK channels molecular biology and structure

Answer 13

• single gene slo or KCNMA1 codes for the BK channel’s pore forming a-subunit
• 4 a-subunits make up a single functional channel
• alternative splicing of a-subunits pre-mRNA
  
  • multiple exons
  • alter voltage and/or ca2+ sensitivity of the channel
  • control surface expression