2.1 Electrophysiological mapping in vivo
The achieved range of blood [K+] was from 2.33 to 6.42 mM. On the
axis from the ischemic zone to the normal zone, two variants of the
distribution of ATs and ARIs were observed at different levels of
[K+]. In the animals with blood [K+] <4.7 mM
(low-normal potassium), the affected area with ST-segment elevation was
heterogeneous, and as a result three electrophysiological zones were
discerned in the mapped area: an ischemic zone with ST-segment elevation
and activation delay, a border zone with ST-segment elevation and no
activation delay, and a normal zone without electrophysiological
abnormalities. The animals with blood [K+] >4.7 mM
(normal-high potassium) had only the ischemic and normal zones and did
not have any transitional area (Fig.1). CV gradually decreased from the
normal to ischemic zone in all animals (Fig.2).
The normal-high potassium animals had more pronounced activation delay
(greater ATs) in the ischemic zone as compared to low-normal potassium
animals (Fig.1), while ARIs were longer in the low-normal potassium rats
in the normal, border, and ischemic zones (Fig.1, 3A). CV at lower
[К+] was greater in all zones of myocardium as compared to CV at
higher [К+] (Fig.2, 3B). It was found that the ARIs and CV were
inversely associated with blood [K+] in linear regression analysis
with adjustment for a zone of myocardium (B = -2.34 95% CI
‑3.448 – ‑1.284), p<0.001; and B = -0.024 95% CI -0.039 –
-0.009, p=0.002, respectively) (Fig.3).
The extrasystolic burden at the 1st min of reperfusion
was greater in animals with low-normal potassium (7.5±2.0 bpm) as
compared to animals with normal-high potassium (1.2±0.4 bpm, p=0.006).
Reperfusion ventricular tachycardia (VT) and fibrillation (VF) incidence
did not differ between the groups (χ2 = 0.079, p=0.779).