NADP+ INFLUENCE FOR ELECTROPHYSIOLOGICAL PROPERTIES OF CARDIOMYOCYTES OF C57BL/6 AND MDX MICE
V.M. Mikhailov,1 G.I. Mamaeva 2
1 Institute of Cytology RAS, St. Petersburg and 2 City Hospital N 31, St. Petersburg;
e-mail: vmikhailov@mail.cytspb.rssi.ru
We have studied the influence of NADP+ on routine ECG in 6 months old C57BL/6 and mdx mice. The animals were anestheized by ether before
ECG recording. ECG registration was made with the speed of 100 mm per sec. The first ECG recording was made before intraperitoneal NADP+ injection in a dose
of 13 or 80 mg/kg. The second ECG recording was made in 10 min after NADP+ injection. Then anesthesia was cut off. The mice were occasionally anestheized 45-60
min later and the third ECG was recorded in 1 h after injection of NADP+. ECG recording was made at a speed of 100 mm/s in the standard leads I, II and III and in the
unipolar leads AvR, AvL and AvF. Values of standard ECG characteristics such as the P wave, intervals PQ, QT, RR, and QRS complex in milliseconds were measured in standard
lead II. We did not observe any differences between ECG magnitudes of 2-3 months old C57BL/6 and mdx mice during trial experiments. Mice of both lines had sinus rhythm of heart
rate. QRS complex in mdx mice mice had a tendency to be larger compared with that in C57BL/6 mice. Heart rates fluctuated between 722 ± 22 and 681 ± 23 beats per
minute. NADP+ influences was studied in 6 months old mice male. The increase in the RR interval and decreased heart rate from 697 ± 2 to 461 ± 23 and 491 ± 28
beats per min for C57BL/6 mice (P < 0.01) and from 722 ± 28 beats per minute to 454 ± 31 beats per min for mdx mice were registered in 10 min after NADP+ injection
in a dose of 80 mg/kg. The increase in the RR interval can be explained by an increase in the interval QT. A statistically significant reduction in the QT interval leading to a decrease
in the RR interval was observed in mdx mice in 1 h after NADP+ injection. NADP+ in a dose 13 mg/kg did not change mdx mice mice ECG
properties significantly. ECG of mdx mice mice were characterized by negative repolarization of T wave in 37 % between all leads. A deal of leads with the negative T
wave repolarization decreased up to 3 % in 1 h after NADP+ injection in a dose of 80 mg/kg. The results have shown that cytomembranes of ventricular cardiac
myocyte and the degree of oxidative stress are the main touches of NADP+ influence in the cases of C57BL/6 and mdx mice mice hearts.
Key words: C57BL/6 and mdx mice, cardiomyopathy, ECG, interval QT, NADP+, T wave repolarization
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