If We Were Able to Artificially Alter the Membrane Permeability

Multiple Choice

If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, .

A) heart rate would decrease, but blood pressure would rise due to the excess sodium present
B) potassium channels compensate and no change in heart rate would occur
C) tetanic contraction would occur due to the short absolute refractory period of cardiac muscle
D) threshold is reached more quickly and heart rate would increase