INFLUENCE OF CHRONIC NON-GASEOUS ACIDOSIS ON BONE TISSUE
Authors: Perepelytsia Yu. V. , Zakhartseva L. M. , Mikhnev V. A. , Ushko Ia. A. 
Published: October 2021

The urgency of the problem is due to the high prevalence among the population in all countries of the world and socio-economic losses associated with serious complications of osteoporosis. Chronic non-gaseous acidosis leads to disruption of many metabolic processes, which causes dysfunction of some organs, namely, can lead to decreased kidney function, exacerbate cardiovascular disease, the development of osteoporosis. Different types of non-gaseous acidosis are accompanied by changes in protein metabolism, which lead to the development of osteoporosis.

Aim: to study the structural features of the bone tissue of the femur in chronic non-gaseous acidosis.

Methods. The experiments were carried out on 60 intact white outbred male rats weighing 120-180 g, which were kept on a balanced diet of vivarium. Chronic non-gaseous acidosis was simulated by daily intragastric administration with a probe for 60 days 20 mmol/kg NH4CL. The control animals were injected with the same amount of tap water. Histological examination and osteometry were used to study the structure, length and thickness of the rat femur. Free, bound, and total oxyproline in rat urine was determined by biochemical method.

Results. In chronic non-gaseous acidosis after 6 months there is a tendency to reduce the length and thickness of the femur, but does not differ significantly from the control group. In the urine of rats of the experimental group, the total oxyproline increases mainly due to an increase in free oxyproline, which indicates the predominance of collagen degradation over repair. The histological structure of the bone is disturbed due to the thinning of the bone beams, the intercellular matrix is disorganized, in some places there is its "defibering" with the formation of foci of destruction and cylindrical "lumens". There is a violation of the crystalline structure of bone tissue, its uneven calcification, the formation of cracks in the bone beams.

Studied literature sources and our research indicate that chronic non-gaseous acidosis has a pathogenic effect on the histological structure of bone. Acidosis is a stress factor that increases the level of glucocorticoids. Glucocorticoids inhibit type I collagen synthesis and increase the expression of collagenase 3, which promotes collagen degradation. Collagen is a source of amino acids that are the substrate for renal ammoniogenesis. Renal ammoniogenesis is a compensatory mechanism in chronic non-gaseous acidosis, which required for restores the normal ratio between fixed cations and anions blood plasma. Thus, the violation of the organic basis of bones is the body's adaptation to chronic non-gaseous acidosis.

Conclusions. Chronic non-gaseous acidosis simultaneously leads to thinning and disorganization of the intercellular matrix, disruption of the crystal structure of bone tissue, which indicates its important role in the development of osteoporosis. In chronic non-gaseous acidosis, the concentration of oxyproline in the urine increases, which is a marker of the destruction of collagen in the organic matrix of bone.