Cell membrane of a cell is freely permeable to three ions X, Y and Z. At resting membrane potential, the respective equilibrium potentials of Xand Y are -30mV and -40 mV.What will happen to the membrane potential if a drug is infused which can block the permeability of Z?
(A) Depolarisation (B) Hyperpolarization (C) No change (D) Hyperpolarization following repolarization
(A) Ans. A. DepolarisationRef: Guyton & Hall 13' ed., ch-5, pg. 61-63.In this question if Z has a reversal potential or original RMP was more negative (e.g., -70 or -90 mV) then closure of C ion channels would shift the RMP closer to reversal potential of A, B thus depolarising the cell