Creating a Cardiac Pacemaker by Gene Therapy - Biopacemaking - page 54

Fig. 4. Occurrence of sustained escape ventricular rhythms in dogs exposed to vagal
stimulation following inoculation of their left posterior fascicles with control adenovirus (a) or
with an adenoviral construct incorporating HCN2 (b) . Escape rhythm in the latter group of
animals is faster, and originates from the left posterior fascicle. Reproduced with permission
from Ref. 71
search for the biological pacemaker, mainly because its effects are limited to diastolic
depolarization and do not affect repolarization, in contrast to I K1 . Further refinement of
biological pacemakers will require a number of issues to be further addressed, of
which an interesting one would be the interplay of an overexpressed I f with an
underexpressed I K1 .