[Comparing the effect of neuronal type Na+channel block on pacemaker activity of C57BL6/J mouse sinoatrial and atrioventricular node]

ABSTRACT

In resent years, neuronal type Na+ channel is one of the important currents for action potential depolarization phase in heart cells. In this study neuronal type Na+ channel is blocked by low concentration of TTX to compare the effect of TTX blocker on pacemaker activity of sinoatrial node [SAN] and atrioventricular node [AVN] of mouse heart. In this experimental study the pacemaker activity of distinct intact SAN and AVN, was recorded before and during consuming 100 nM TTX and cycle length [CL] was measured. Data was analyzed using T test. 100 nM TTX increased CL on SAN preparations by 22.2 +/- 6% and on AVN preparations by 52.5 +/- 13.5%. These changes were significant in the two nodes. It is passible to conclude that; the neuronal type Na+ channel was present in the two nodes, and the effect of TTX on CL of the two nodes was different