electrophysiology rig

Question 1

what are the 5 control blocks on the instrument front panel?

Answer 1

1) voltage electrode (Vm)
2) bath electrodes (Im)
3) clamp
4) commands
5) current electrode

Question 2

what’s on the instrument rear panel?

Answer 2

1) BNC connector for GAIN TELEGRAPH INPUT
2) BNC connector for Ve X 10 output
3) an alarm on/off switch
4) binding posts for circuit ground and chassis ground

Question 3

voltage meter

Answer 3

reports the membrane voltage of the cell, range of +/- 199.9mV

Question 4

voltage probe connector

Answer 4

7-pin DIN connector for attachment of the voltage probe to the instrument

Question 5

Vm offset control

Answer 5

10-turn potentiometer providing up to +/- 200mV at the voltage probe input for offset of membrane junction potentials

Question 6

Vm electrode test control

Answer 6

used to determine the internal resistance of the voltage probe (10mV/M-ohm of probe resistance)

Question 7

Vm BUZZ push button

Answer 7

facilitates penetration of the voltage electrode by producing a 1kHz square wave at the pipette tip

Question 8

Vm x10 output BNC

Answer 8

reports the membrane voltage in mV multiplied by 10

Question 9

current meter

Answer 9

reads the voltage (Ve) of the current electrode when the clamp mode selector switch is off

Question 10

current meter (clamp mode selector switch set to slow or fast)

Answer 10

current meter displays the current sensed by the bath electrode

Question 11

gain select controls allows range of gain to be set from:

Answer 11

0.01 to 100

gain selector switch = 0.1 to 10, gain multiplier = 0.1, 1, 10x

Question 12

I monitor BNC

Answer 12

current outputs at full bandwidth (10 kHz)

Question 13

I monitor filtered BNC

Answer 13

current outputs filtered at 1 kHz by an integral 4-pole Bessel filter

Question 14

clamp mode selector: off

Answer 14

the clamp amplifier is disconnected from the current electrode, voltage difference between the current electrode and the bath electrode is read on the meter in the bath electrodes block

Question 15

clamp mode selector: slow

Answer 15

• useful for screening oocytes or when high clamp speeds are not required
• clamp speed = 0.5ms
• measured currents are displayed on the bath electrodes meter in uA

Question 16

clamp mode selector: fast

Answer 16

• used for most oocyte clamping
• clamp speed is limited by the resistance of the current electrode and the oocyte membrane capacitance
• fast clamp speed = 350us

Question 17

gain control

Answer 17

a single turn potentiometer which varies the full bandwidth open-loop gain from 0 to 2000

Question 18

Ve offset

Answer 18

range of +/- 200mV, used to adjust the offset voltage of the current electrode

Question 19

Ve x10 output BNC

Answer 19

monitors the voltage of the current electrode (x10) when the clamp mode selector switch is off

Question 20

gain telegraph output BNC

Answer 20

provides a DC voltage indicating the gain setting of the instrument, output varies from 0.2 to 2.6 volts in 200mV steps

Question 21

model cell

Answer 21

a simple circuit that mimics the properties of recording from an actual oocyte

Question 22

follicular layer

Answer 22

connective tissue that is rich in collagen

Question 23

collagenase

Answer 23

an enzyme that will break the peptide bonds of collagen, thus releasing individual oocytes

Question 24

denuded oocytes

Answer 24

individualized oocytes

Question 25

animal pole of oocytes

Answer 25

dark pigmentation, contains the nucleus

Question 26

vegetal pole of oocytes

Answer 26

lighter pigmentation, pale yellow colour

Question 27

what defines stage VI oocytes?

Answer 27

light-coloured band separating the animal and vegetal poles

Question 28

what does it mean if oocytes are covered with blood vessels?

Answer 28

the oocytes are undergoing resorption

Question 29

stage I oocytes

Answer 29

oocytes are clear and transparent (50-300um)

Question 30

stage II oocytes

Answer 30

oocytes are white and opaque (300-450um)

Question 31

stage III oocytes

Answer 31

oocytes are lightly pigmented all over (450-600um)

Question 32

stage IV oocytes

Answer 32

oocytes are starting to have yolk protein deposited into their cytoplasm and the pigment is primarily concentrated to the upper animal hemisphere (600-1000um)

Question 33

stage V oocyte

Answer 33

oocytes are accumulating yolk and have a darker pigmented colour (1000-1100um)

Question 34

stage VI oocyte

Answer 34

oocytes are fully grown and have progesterone receptors on their plasma membrane (1100-1300um)