Aim of the study was to evaluate the activity of the adenosine A2A-receptor during lithokinetic therapy in patients with stones localized in the upper third of the ureter.
Material and methods. The study was prospective and included 61 patients with stones in the upper third of the ureter. Within 7 days, patients underwent standard LCT, including α1A-blocker, NSAIDs and antibiotics. According to the data of visual control of calculus traffic, the cohort of patients was divided into two groups: with effective (group 1) and ineffective (group 2) calculus elimination. The activity of the adenosine A2A-receptor was studied in vitro on platelet suspension. Platelet aggregation was assessed by the turbidimetric method on a ChronoLog analyzer (USA).
Results. At the time of hospitalization, A2A-receptor hyporeactivity was detected in patients. After 7 days of standard LCT in patients of the 1st group, elimination of calculi from the upper third of the ureter was observed; the effect was achieved with hyperreactivity of the A2A-receptor. The kinetics of adenosine biogenesis and intracellular signaling associated with the stimulation of the A2A receptor underlie the rapid and slow elimination of stones.
Conclusion. Standard LCT can influence on the activity of the adenosine A2A-receptor, which modulates the relaxation of ureteral SMCs. Analysis of the purine nucleotides transformation in the wall of the urinary tract during obstruction, and study of the adenosine effect on the muscle tone of SMC during prolonged dilatation of the ureter will allow to evaluate the perspective of using A2А-receptor agonists to improve the tactics of conservative treatment of nephrolithiasis.

Keywords: adenosine A2A-receptor, ureteral motility, lithokinetic therapy, nephrolithiasis