Objective: The aim: Studying changes in the ultrastructure of blood circulatory capillaries of the myocardium of mature rats with hypothyroidism and arterial hypertension.
Patients and methods: Materials and methods: Experiments were conducted on (240 days) 10 ISIAH (inherited stress-induced arterial hypertension) line rats with AH (arterial hypertension), 10 Wistar line rats with congenital hypothyroidism and 10 intact animals. Arterial pressure was measured, and the development of hypothyroidism was controlled by the immune enzyme method. The study of the left ventricle myocardium of the rat heart was carried out by electron microscopic and morphometric studies.
Results: Results: In in rats with AH the following changes were observed in the blood capillaries of the myocardium: decrease in the number of capillaries; disturbance of blood circulation; the number of organelles of the biosynthetic plan and structures involved in the transendothelial transfer of substances decreased in endothelial cells; lysis and edema of the latter; mucinous perivascular edema, confirmed by the accumulation of fine-fibrillar structures, collagen fibers, cellular detritus. By the same term, in the group with congenital hypothyroidism, dystrophic-destructive changes in the blood capillaries of the myocardium acquired the highest degree, which resulted in a decrease in their number due to destruction. Ultrastructure of the biosynthetic plan organelles and structures of the transendothelial transfer of substances were in decompensated state.
Conclusion: Conclusions: The rats (in 240 days) with AH and congenital hypothyroidism express breakdown of compensatory processes in the capillaries of the myocardium. This is manifested by the further dilution of capillaries, the development of hypoxic state in them as well as mucinous edema of interstitium, the decrease of activity of biosynthetic and transport processes.
Keywords: hypertension; blood capillaries; congenital hypothyroidism; electron microscopy; myocardium.