Spatial Organization Types of Sinoatrial Node in Dogs with Different Body Functional Reserve Levels

The aim of the investigation was to reveal the spatial organization types of sinoatrial nodes in animals with different levels of body functional reserve after a single maximal exercise.

Materials and Methods. The research was carried out on 24 male mongrel dogs. Treadmill run under laboratory conditions was used to model a single maximal exercise. The exercise time was individual for each animal due to its cardio-respiratory system. A body functional reserve level was determined by the running time to refusal and the heart rate (HR) during the exercise. We studied the sinoauricular area structure using light and transmission electron microscopy. Tissue organization of myocardium was analyzed using the methods of stereology.

Results. According to HR dynamics, we distinguished two main types of functional response to maximal (excessive) exercise: type I, high HR during the running, and type II, low HR. The response types on exercise also differed in the running time and resting HR (p<0.05).

Based on stereological test findings we described the peculiarities of spatial organization of conductive and contractile myocardium in animals with different functional responses characterized by various ratios of the main tissue components. Stereological parameters in type I animals were similar to those in intact animals of a control group. Conductive and contractile myocardium in type II animals significantly differed in a relative volume of cardiomyocytes and connective tissue components from those in controls and type I animals.

Conclusion. The results of morphological studies of sinoauricular region in animals with different levels of functional body reserve compared to physiological parameters enable to predict the structural changes in the sinoatrial node area after an excess motor load.

1. Perrino C., Gargiulo G., Pironti G., Franzone A., Scudiero L., De Laurentis M., Magliulo F., Ilardi F., Carotenuto G., Schiattarella G.G., Esposito G. Cardiovascular effects of treadmill exercise in physiological and pathological preclinical settings. Am J Physiol Heart Circ Physiol 2011; 300(6): H1983–H1989, http://dx.doi.org/10.1152/ajpheart.00784.2010.
2. Wilson M.G., Ellison G.M., Cable N.T. Basic science behind the cardiovascular benefits of exercise. Heart 2015; 101(10): 758–765, http://dx.doi.org/10.1136/heartjnl-2014-306596.
3. Zilinski J.L., Contursi M.E., Isaacs S.K., Deluca J.R., Lewis G.D., Weiner R.B., Hutter A.M. Jr., d’Hemecourt P.A., Troyanos C., Dyer K.S., Baggish A.L. Myocardial adaptations to recreational marathon training among middle-aged men. Circ Cardiovasc Imaging 2015; 8(2): e002487, http://dx.doi.org/10.1161/CIRCIMAGING.114.002487.
4. Stepien R.L., Hinchcliff K.W., Constable P.D., Olson J. Effect of endurance training on cardiac morphology in Alaskan sled dogs. J Appl Physiol 1998; 85(4): 1368–1375.
5. D’Andrea A., Caso P., Sarubbi B., Limongelli G., Liccardo B., Cice G., D’Andrea L., Scherillo M., Cotrufo M., Calabrò R. Right ventricular myocardial adaptation to different training protocols in top-level athletes. Echocardiography 2003; 20(4): 329–336, http://dx.doi.org/10.1046/j.1540-8175.2003.03038.x.
6. Kukielka M., Seals D.R., Billman G.E. Cardiac vagal modulation of heart rate during prolonged submaximal exercise in animals with healed myocardial infarctions: effects of training. Am J Physiol Heart Circ Physiol 2006; 290(4): H1680–H1685, http://dx.doi.org/10.1152/ajpheart.01034.2005.
7. Ferasin L., Marcora S. Reliability of an incremental exercise test to evaluate acute blood lactate, heart rate and body temperature responses in Labrador retrievers. J Comp Physiol B 2009; 179(7): 839–845, http://dx.doi.org/10.1007/s00360-009-0367-z.
8. Kemi O.J., Wisløff U. Mechanisms of exercise-induced improvements in the contractile apparatus of the mammalian myocardium. Acta Physiol (Oxf) 2010; 199(4): 425–439, http://dx.doi.org/10.1111/j.1748-1716.2010.02132.x.
9. La Gerche A., Burns A.T., Mooney D.J., Inder W.J., Taylor A.J., Bogaert J., Macisaac A.I., Heidbüchel H., Prior D.L. Exercise-induced right ventricular dysfunction and structural remodelling in endurance athletes. Eur Heart J 2012; 33(8): 998–1006, http://dx.doi.org/10.1093/eurheartj/ehr397.
10. Carneiro-Júnior M.A., Prímola-Gomes T.N., Quintão-Júnior J.F., Drummond L.R., Lavorato V.N., Drummond F.R., Felix L.B., Oliveira E.M., Cruz J.S., Natali A.J., Mill J.G. Regional effects of low-intensity endurance training on structural and mechanical properties of rat ventricular myocytes. J Appl Physiol 2013; 115(1): 107–115, http://dx.doi.org/10.1152/japplphysiol.00041.2013.
11. Kim K.S., Ardell J.L., Randall W.C., Pomeroy G., Calderwood D. Cardiac responses to exercise in the dog before and after destruction of the sinoatrial node. Eur J Appl Physiol Occup Physiol 1986; 55(3): 253–258, http://dx.doi.org/10.1007/bf02343796.
12. Stein R., Medeiros C.M., Rosito G.A., Zimerman L.I., Ribeiro J.P. Intrinsic sinus and atrioventricular node electrophysiologic adaptations in endurance athletes. J Am Coll Cardiol 2002; 39(6): 1033–1038, http://dx.doi.org/10.1016/s0735-1097(02)01722-9.
13. Baldesberger S., Bauersfeld U., Candinas R., Seifert B., Zuber M., Ritter M., Jenni R., Oechslin E., Luthi P., Scharf C., Marti B., Attenhofer Jost C.H. Sinus node disease and arrhythmias in the long-term follow-up of former professional cyclists. Eur Heart J 2008; 29(1): 71–78, http://dx.doi.org/10.1093/eurheartj/ehm555.
14. Monfredi O., Dobrzynski H., Mondal T., Boyett M.R., Morris G.M. The anatomy and physiology of the sinoatrial node — a contemporary review. Pacing Clin Electrophysiol 2010; 33(11): 1392–1406, http://dx.doi.org/10.1111/j.1540-8159.2010.02838.x.
15. Radzievskiy A., Priymakov A., Oleshko V., Yashanin N. About accumulation, expenditure and redistribution of functional reserves in a human body. Nauka v olimpiyskom sporte 2002; 3–4: 110–119.
16. Davidenko D.N. A problem of sportsman’s body adaptation reserves. Uchenye zapiski universiteta im. P.F. Lesgafta 2005; 18: 15–24.
17. Lee M.C., Wood R.H., Welsch M.A. Influence of short-term endurance exercise training on heart rate variability. Med Sci Sports Exerc 2003; 35(6): 961–969, http://dx.doi.org/10.1249/01.mss.0000069410.56710.da.
18. Ostojic S.M., Stojanovic M.D., Calleja-Gonzalez J. Ultra short-term heart rate recovery after maximal exercise: relations to aerobic power in sportsmen. Chin J Physiol 2011; 54(2): 105–110, http://dx.doi.org/10.4077/CJP.2011.AMM018.
19. Rathore N.S., Moolchandani A., Sareen M., Rajput D.S. Effect of treadmill exercise on some physiological and hematological parameters in German Shepherd dogs. Veterinary Practitioner 2011; 12(1): 38–39.
20. Neves F.J., Carvalho A.C., Rocha N.G., Silva B.M., Sales A.R., de Castro R.R., Rocha J.D., Thomaz T.G., Nóbrega A.C. Hemodynamic mechanisms of the attenuated blood pressure response to mental stress after a single bout of maximal dynamic exercise in healthy subjects. Braz J Med Biol Res 2012; 45(7): 610–616, http://dx.doi.org/10.1590/S0100-879X2012007500083.
21. Piccione G., Casella S., Panzera M., Giannetto C., Fazio F. Effect of moderate treadmill exercise on some physiological parameters in untrained Beagle dogs. Exp Anim 2012; 61(5): 511–515, http://doi.org/10.1538/expanim.61.511.
22. D’Ascenzi F., Pelliccia A., Natali B.M., Zacà V., Cameli M., Alvino F., Malandrino A., Palmitesta P., Zorzi A., Corrado D., Bonifazi M., Mondillo S. Morphological and functional adaptation of left and right atria induced by training in highly trained female athletes. Circ Cardiovasc Imaging 2014; 7(2): 222–229, http://doi.org/10.1161/CIRCIMAGING.113.001345.
23. Biryukova O.V., Baranov N.A., Vasyagina T.I. Adaptive response of the heart and peripheral vasculature on single physical exercises in experiment. Sovremennye tehnologii v medicine 2015; 7(2): 55–61, http://dx.doi.org/10.17691/stm2015.7.2.07.
24. Vasyagina T.I., Edeleva N.K., Biryukov Yu.V. Cresyl violet and basic fuchsin staining technique for semi-thin sections of large areas for light microscopy. Morfologiya 2011; 140(5): 74.
25. Silkin Yu.R. Strukturno-funktsional’naya organizatsiya miokarda levogo zheludochka pri adaptatsii organizma k dvigatel’nym nagruzkam. Avtoref. dis. … dokt. med. nauk [Structural and functional left ventricular myocardial organization in body adaptation to motor loads. DSc Thesis]. Moscow; 2000.
26. Vysochin Yu.V., Denisenko Yu.P. Modern concepts of physiological mechanisms of urgent sportsmen’s adaptation to exercises. Teoriya i praktika fizicheskoy kul’tury 2002; 7: 2–6.
27. Kornyakova V.V., Konway V.D. The role of infringement of metabolism purines in damage of cardiomyocytes in rats under physical activities. Omskiy nauchnyy vestnik 2012; 1(108): 96–99.
28. Gritsyuk T.V. Morfofunktsional’nye izmeneniya v dvigatel’nykh neyronakh spinnogo mozga, serdechnoy i skeletnoy myshtsy nepolovozrelykh belykh krys pri vozdeystvii fizicheskikh nagruzok i v usloviyakh primeneniya fitopreparatov. Avtoref. dis. … kand. med. nauk [Morphofunctional changes in motor neurons of spinal cord, cardiac and skeletal muscles of immature white mice when exposed to exercises and under phytopreparation therapy. PhD Thesis]. Saint Petesburg; 1994.

Vasyagina T.I., Biryukova О.V. Spatial Organization Types of Sinoatrial Node in Dogs with Different Body Functional Reserve Levels. Sovremennye tehnologii v medicine 2016; 8(2): 40, https://doi.org/10.17691/stm2016.8.2.05