Peculiarities of transtubular transport of calcium and phosphates in the dynamics of the development of alloxan-induced experimental Diabetes Mellitus

Olha Olenovych; Anatoliy Gozhenko; Yelyzaveta Tkach

Olha Olenovych Department of Clinical Immunology, Allergology and Endocrinology, Bukovinian State Medical University, Chernivtsi, Ukraine
Anatoliy Gozhenko State Enterprise Ukrainian Scientific Research Institute of Transport Medicine of Ministry of Health of Ukraine, Odesa, Ukraine
Yelyzaveta Tkach Department of Internal Medicine, Clinical Pharmacology and Occupational Diseases, Bukovinian State Medical University, Chernivtsi, Ukraine

Keywords: alloxan, experimental diabetes mellitus, renal function, calcium, phosphates

Abstract

The objectives of the research were to study the peculiarities of the intrarenal mechanisms of calcium and phosphates homeostasis regulation under the condition of experimental diabetes. The experiments were carried out on 54 white non-linear mature male rats – 24 animals with 11-, 26- and 46-day long alloxan-induced experimental diabetes mellitus and 30 intact animals of the control. Creatinine, sodium, calcium and phosphates in the urine were determined. Electrolytes excretion, calcium-phosphorus, calcium- and phosphorus-creatinine, sodium-calcium and sodium-phosphorus ratios in urine were calculated. The study’s results demonstrated the increase of sodium-dependent excretion of calcium and phosphates, mainly hyperfusional in nature, on the 11th day of the experiment provided by the distal tubules with underlying functional overstrain of the tubulo-tubular feedback. The predominance of sodium-dependent distal counter-transport of calcium was preserved on the 26th day of the experiment, while phosphate reabsorption was related mainly to the proximal tubules. Reabsorptive defect of phosphates in the proximal and distal tubules was a probable reason for the increase of their urine content and maximal strain of phosphate homeostasis mechanisms on the 46th day of the experiment, preserved concerning calcium. These results evidence the preserved compensatory and functional autoregulatory renal mechanisms for calcium and phosphate exchange.