[DIFFERENCES OF EXENATIDE EFFECTS ON GLYCEMIA AND RENAL WATER AND ION EXCRETION IN FROGS AND RATS].

The aim of the present study was to compare effects of glucagon-like peptide-1 (GLP-1) mimetic exenatide on glucose and water-salt homeostasis in animals with different level of renal tubular proximal reabsorption - rats (Rattus norvegicus) and frogs (Rana temporaria). Following glucose tolerance test, in rats exenatide promoted rapid recovery of normoglycemia, whereas in frogs delayed this process. In water-loaded rats exenatide essentially augmented solute-free water clearance and enhanced natriuresis in furosemide-treated rats.-In frogs exenatide did not alter urinary flow rate, urinary sodium excretion and solute-free water clearance under water diuresis and furosemide treatment. It is suggested that the invol- vement of GLP- 1 in regulation of water-salt homeostasis in mammals should be preceded by key evoluti- onary transformation - increase in glomerular filtration rate and proximal tubular reabsorption.