KINETICS OF THE PROCESSES OF GROWTH OF LINEAR SIZES AND NUMBERS OF CARDIOMYOCYTES IN THE MYOCARDIUM COMPLEX (LV + MZP) BEFORE AND AFTER THE RAT-BIRTH

Zahoruiko G. E., Zahoruiko Yu. V., Shmulich A. V.

BIOLOGY

Scentific article

Wistar rats were used: 15-16 and 20-21 diurnal embryos, newborns, 2.5 and 5, 7.5 and 10, 15, 20, 25, 30, 35, 40 and 45 day-old rats. From compact and trabecular layers of the myocardium of rats of different ages, ultrafine sections were prepared. In a series of negatives (6x9) cm2 obtained at 2000х, Vv (in%) of dark (d) and light (l) CMCs was determined in the parenchyma (LV + MZP). At the location of the nucleus, a smaller diameter (d, μm) of CMC images was measured. According to the formula: Vcmc = Vс (μm3) • 100% / Vvс (%) determined the volumes of CMC (μm3). Here Vn is the volume of the nucleus (μm3), and Vv is the relative volume of the CMC core (%). The number of CMCs in the parenchyma (LV+MZP) was determined by the formula: Nсmc = mpar / ρ • Vcmc. Here mpar is the parenchyma mass (mg), ρ = 1.05 g / cm3 = 1.05 mg / 109 μm3 is the average value of myocardial density, Vcmc is the CMC volume (μm3). It was found that in the process of embryogenesis, the content of moderately dehydrated d-CMC increases in the parenchyma of the myocardium, which are in a state of physiological rest. The highest value of Vv d-CMC is equal to 41%, it is determined in the parenchyma of the trabecular myocardium of newborns. In the process of postnatal development of rats (1-7.5) days, activation of the contractile function of reserve “resting” d-CMC occurs, the relative volume of which decreases from 41% to 0%. Vv dual-core CMC in the parenchyma of the myocardium increases from 5% in newborns to 100% by 15 days after the birth of the rat. In the process of ontogenesis (15 days before birth and 45 days after), a continuous increase in the linear dimensions of CMC in a compact and trabecular myocardium is observed. For hypertrophic CMC of a compact myocardium, characteristic growth of longitudinal dimensions, in trabecular myocardium – growth of transverse sizes of myocytes. By 20 days after the birth of the rat, the differences in the linear characteristics of CMC of the compact and trabecular myocardium are leveled. After the birth of the rat, the proliferation of CMC in the parenchyma (LV + MZP) gradually fades to 15 days. For this period of time the number of CMC increases 2.5 days, (from 0.724 to 1.56) x 107. After 15 days, Ncmc ≈const. Consequently, the increase in the number of CMCs in the parenchyma myocardium complex (LV + MZP) is completed by 15 days after the birth of Wistar rats.

Wistar rats, ontogeny, heart, cardiomyocytes

1. Dovgal HV, Shevchenko IV. Yltrastrukturni osnovi kardiotoksichnoy dii acetaty svincy na morfogenez serdca. Visnik probl. biol. i med. 2018;2(144);306-10. [in Ukrainian].
2. Lushnikova EL, Nepomnyashchikh LM, Young NA. Strukturnaya reorganizaciya miokarda krys i chislennost’ kardiomiocitov pri deystvii doksorybicina і triterpenoidov. Fundаmentalnie issledovaniya. 2011;6;98-102. [in Russian].
3. Postnikova OA. Gisto-stereologicheskiy i ultrastrukturniy analiz gipertrofii miokarda krys. Wistar, SHR, W\SSM [avtoreferat]. Novosibirsk, 1999. 27 s. [in Russian].
4. Gnatyuk MS, Tatarchuk LV, Prishlyak AM. Víkoví osoblivostí zmín yaderno-tsitoplazmatichnikh vídnoshen v kardíomíotsitakh sertsya doslídnikh tvarin. Tavrich. mediko-biol. vestnik. 2010;13(4);29-32. [in Ukrainian].
5. Nepomnyashchikh LM, Lushnikova YeL. Morfometriya i stereologiya gipertrofii serdtsa. Novosibirsk: «Nauka»; 1986. 304 s. [in Russian].
6. Avtandilov GG. Osnovy kolichestvennoy patologicheskoy anatomii. M.: «Meditsina»; 2002. 240 s. [in Russian].
7. Zahoruiko GE, Zahoruiko YuV. Vozrastnye izmeneniya razmerov i chisla kardiomiocitov, ix yader v processe prenatalnogo i rannego postnatalnogo razvitiya serdca krys. Visnik probl. biol. i med. 2017;3(141):304-11. [in Ukrainian].
8. Najdich AM. Neodnorodnost levogo zheludochka i remodelirovanie miokarda. Byull. Sibir. mediciny. 2006;1;38-45. [in Russian].
9. Scheider W, Portfeld T. Physiol. Med. Biol. 2000;45:459-78.
10. Zahoruiko GE, Zahoruiko YuV, Shmulich AV. Zakonomernosti kinetiki rosta massy serdca, kompleksa (LZh+MZhP) i parenximy miokarda v prenatalnom i postnatalnom ontogeneze krys. Visnik probl. biol. i med. 2018;2(144);87-90. [in Russian].
11. Rumyantsev PP. Kardiomiotsity v protsessakh reproduktsii, differentsirovki i regeneratsii. L.: «Nauka»; 1982. 288 s. [in Russian].
12. Zahoruiko GYe, Zahoruiko YuV. Morfometricheskiy analiz prenatalnogo i postnatalnogo sozrevaniya kardiomiotsitov krys. Vísnik problem bíol. í med. 2017;2(136):290-4. [in Russian].

«Bulletin of problems biology and medicine» Issue 4 part 1 (146), 2018 year, 36-39 pages, index UDK 612.172 : 611.127-018

10.29254/2077-4214-2018-4-1-146-36-39