Smooth muscle cells from the arterial wall of placental chorion were studied at 39-40-week gestation. The content of mono- and binuclear tetraploid myocytes was higher in sites of arterial branching and turns (27.3% vs. 4.4% straight parts of the arteries; DNA cytophotometry data). Mitoses were found only in these arterial regions (0.18%). Regional changes in the sizes of diploid and polyploid myocytes were detected, associated with the blood flow pattern in the chorion; myocyte hypertrophy was 17-fold more incident in sites of arterial turns and branching than in straight arteries. Possible causes of changes in the proliferative characteristics and subsequent growth of the chorionic arterial wall myocytes are discussed.

Brain and kidneys from 15 control and 70 experimental puppies with hemodynamic model of coarctation of the aorta were examined. The number of regulatory muscle formations was increased in the brain and decreased in the kidneys during modeling of aorta coarctation associated with hyper- and hypotension in the corresponding basins. The location of these structures in cerebral and renal distribution and resistance vessels is analyzed.

In coarctation of the aorta tangential tension of the wails of renal arteries and arterioles decreases, which leads to a drop in the glycogen content and activity of respiratory enzymes in medial leiomyocytes and accumulation of glycosaminoglycans in the media. This is accompanied by atrophy and sclerosis of the vessels. The observed changes disappear after surgical correction.Key Words: coarctation of aorta; renal arteries; tangential tension; reversibility Structural changes occurring in the blood vessels of vital organs associated with circulation disorders caused by congenital cardiac disorders have been poorly investigated. The information on the reversibility of these changes is scarce. However, this issue is of theoretical and practical importance, since the condition of a patient and results of surgery depend on the state of his/her vascular bed.Our goal was to examine structural changes of renal arteries and arterioles in experimental coarctation of the aorta and after its correction, and to find out how these changes are related to tangential tension of the vascular wall. MATERIALS AND METHODSCoarctation of the aorta was modeled in 20 puppies as described previously [4]. The animals were observed for 6-12 months, after which 10 dogs were removed from the experiment, and I0 dogs were subjected to repeated surgery with dissection of the narrowed site and implantation of a fluorolan-lavsan prosthesis. These dogs were observed for 6-12 months. Control group consisted of I0 dogs of the same age. Department of Operative Surgery with Topographic Anatomy, Department of Pathological Anatomy, Yaroslavl State Medical AcademyThe dogs were euthanized by bleeding under Promedol-ether anesthesia. Samples were taken from various sites of the kidneys, fixed in 10% neutral formalin and Camoy's fluid, and embedded in paraffin. Sections were stained with hematoxylin and eosin and by the method of Masson and Hart. Interlobar, arcuate, and interlobular arteries and afferent and efferent glomerular arterioles were measured with the ocular-micrometer. The thickness of arterial media and the cross-section area were calculated from conventional formulas [1]. Smooth muscle cells were counted in the media of interlobular arteries. The size of these cells was assessed by the size of their nuclei. Glycogen in the media of renal vessels was revealed by PAS-reaction; glycosaminoglycans (GAG) were identified by the method of Hate. Activities of succinate dehydrogenase (SDG) and cytochrome oxidase (CCO) were measured on cryostat sections using nitro blue tetrazolium. The enzyme activities and glycogen and GAG contents in the kidneys were calculated as described [7]. Blood pressure in renal arteries was measured with a mercury manometer before sacrifice. Tangential tension of the renal artery wall was calculated from the following formula: T = PxR/dx133.3, where P is the pressure (mm Hg), R is the radius of blood vessel (g), d is the thickness of arterial wall (g), and 133.3 is the correction factor for SI units. The results were process...

AnnotationHistological, morphometric, cytophotometry and statistical methods studied isolated smooth muscle cells at sites of the renal arteries with different hemodynamic conditions in newborns. It is shown that the population of smooth muscle cells on the straight sections of the renal arteries represented subpopulations of small, medium and large mononuclear cells. In the area of the arteries blood fl ow dividers, characterized by turbulence, twists, recycling and complex distribution of shear stress on the vascular wall, there is a pronounced polymorphism in the structure of the arteries of the population. Smooth muscle cells in these hemodynamic conditions, undergo hypertrophy and hyperplasia polyploidization. Phenotypic modulation myocytes occurring in arteries with high branching, anastomosing, many turns may initiate the development of hypertension, heart failure, ischemia, diabetes and obesity.