VANADYL SULFATE DIFFERENTLY INFLUENCES INSULIN-RESPONSE TO GLUCOSE INISOLATED PANCREAS OF NORMAL RATS AFTER IN-VIVO OR IN-VITRO EXPOSURE

The effect of the antidiabetic agent vanadyl sulphate (VOSO4) on the e ndocrine pancreas function of normal rats was studied using the isolat ed pancreas preparation. A short-term (8 days) i.p. treatment (15 mg/k g per day) resulted in attenuation of high glucose-stimulated insulin release, at day 9 but also at days 19, i.e., after full recovery of ap petite and weight, while blood and pancreas vanadium concentrations we re still elevated. Six months of oral VOSO4 treatment (0.75 mg/ml in d rinking water) resulted in elevated vanadium concentrations while gluc ose-stimulated insulin release was attenuated as compared to pair-fed animals. Conversely, when directly perfused in pancreas, VOSO4 potenti ated glucose-stimulated insulin release. These apparently opposite eff ects may be related to the ability of VOSO4 to exert both peripheral i nsulinomimetic effects - leading to chronic reduction in insulin deman d -, and a direct pancreatic insulinotropic activity.