Urethane influence in the urine formation in swiss rats and syrian hamster

Urethane is an anaesthetic agent with minimal cardiovascular and respiratory system depression with long-lasting (6-10h) effects. Its carcinogenic potential avoids it from veterinary use. Either, the knowledge of its effects over the circulating catecholamines (cortisone and corticosterone), with reflects in the muscles physiology, it is widely used in pharmacological studies in laboratory species. At the first minutes, Urethane induces a hyperglycaemia condition due the insulin concentration decrease, later than, the insulin concentration and the condition becomes in hypoglycaemia, but the Urethane interfering in the urine production mechanisms has not been described. It is accepted that the glycolic level would not interferes in the kidney function, except in chronic states, notably associated with insulin related diseases. The relative high biological half-life of 177Lu-Dotatate allows its use in biodistribution studies among small animals whose metabolic rates are so fast that would be impossible observe them with the most part of the labeled molecules. During the performance of a cross-species extrapolation study using Urethane as anaesthesia and 177Lu-Dotatate as metabolic tracer, was observed the Urethane influence over urine formation in Swiss rats and Syrian hamster (Mesocricetus auratus). The objective of this work is only describes the Urethane action over the urine production. Firstly, four male inbread Wistar Swiss rats (±250 g), are anesthetized, with around 1200 mg/kg, i.p., in groups of two. One rat from each group get ahead to the injection of 177Lu-Dotatate and Gamma camera in vivo study, the second ones, anesthetized, waited under warming lights until more than one hour to initiate the biodistribution study. The scintillographical images shown the radiopeptide stopped at the kidneys and the urinary empty in the animals who attempt more than one hour before enter to radiopharmaceutical injection and Gamma camera imaging procedures. The rates of transfer from the tail to the whole body were also significantly different in the two rat groups. A new set of experiments performed with five male inter outbread, Syrian hamsters (±50g), anesthetized one to one, each time, shown hamster sensibility in relation of Urethane concentration. The minimal dose that induced anaesthetic state in hamsters and followed the complete biodistribution study was 1000 mg/kg, i. p.. Whereas, higher recommended dose (1200 - 2000 mg/kg, i. v.) injection, caused the same blockage of urine production effect observed in longer post anaesthesia time in the rats. Considering the CNS (Central Nervous System) influence over the blood pressure and kidney function, these results were a sign that urine production rate could be related with the Urethane dose and the time after its injection. (author)