In an oxygen-sensitive animal cell a particular class of ‘leak’ or ‘background’

Question

In an oxygen-sensitive animal cell a particular class of ‘leak’ or ‘background’ K+ channels contributes significantly to the resting potential of approximately –72 mV. Exposure to medium containing low oxygen (hypoxia) causes some of these K+channels to close. Assuming EK = -85 mV, answer the following:

a) Predict the effect of hypoxia on membrane potential of this cell.

b) What is the effect of hypoxia on membrane resistance?

c) What is the “driving force” on K+ in the resting cell and what is its direction? What happens (qualitatively) to the magnitude of this driving force during hypoxia?

d) What cellular mechanism would this cell need to maintain the steady state?

Explanation / Answer

a. effect of hypoxia on membrane potential;

answer; the resting memberane potential is primarily controlled by the selective permeability of the potassium channels .Hypoxic state causes the depolarization of the cell . the leak channels lack voltage dependence

b.What is the “driving force” on K+ in the resting cell and what is its direction? What happens (qualitatively) to the magnitude of this driving force during hypoxia?

when an ion is not in equlibrium state the electrochemichal driving force act on the ion ,causing the net movement of ion across the electrochemichal gradient . the driving force is quantified by the difference between the memberane potential and ion equlibrium potential . the driving force is the net electromotive force that act on the ion

Vd =Vm -Vek

= -72- 85 = -13 mv

the direction of the movement is towards the hyperpolarisation during hypoxia that is teh influx of the ions into cell is more , there will be rapid depolarization of the channels occurs .

c.What cellular mechanism would this cell need to maintain the steady state?

there will be slow firing of the potassium channels ,leading to slow depolarisation state of the leading to maintain steady state .

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