Following the observation ( 1 ) that administration of 2-Deoxy-D-Glucose (2-DG) to the eviscerated-nephrectmized rabbit decreases the amount of glucose required to maintain a constant blood sugar level, data have been presented to support the hypothesis that 2-DG acts as a metabolic blocking agent inhibiting glucose utilization. Thus, in spite of the increased blood glucose level following 2-DG in the rat(2), dog(3) and man (4), a condition results which has been termed "cellular hypoglycemia" or cellular glucopenia (2). Since the blood sugar level can affect secretion of adrenal medullary hormones we have tested the effect of 2-DG on secretion of adrenaline and noradrenaline in the intact rat. When positive results were found, additional experiments were carried out in rats with denervated adrenal glands.Material and methods. 2-DG was obtained from the Aldrich Chemical Co., Milwaukee, Wis., through the courtesy of the Cancer Chemotherapy National Service Center, NIH, Bethesda. In all instances 2-DG was administered subcutaneously ( s.c.) in water solution (50 mgiml). In control animals a corresponding quantity of distilled water was injected. Regular insulin (Insulin Vitrum) was injected undiluted S.C. B l d glucose concentrations were determined colorimetrically using condensation with 0-toluidine( 5 ) ; in this procedure 2-DG gives only one-tenth of the color produced by equal quantities of glucose within the range of 50-1000 mg %. Tail vein blood was used.Adrenaline and noradrenaline production were judged by urinary excretion of free catechol amines, estimated fluorimetrically (6). To obtain sufficient amounts, urine was collected over 8-12 hours from groups of 2-4 ~ *This work was supported by grants from Swedish Medical Research Council, Magn. Bergwall Foundation and The AhlCn Foundation. rats in metabolic cages. At the end of each experiment the catecholamine content of the adrenals was estimated by the same procedure after extraction with 3 % trichloracetic acid but without absorption on alumina.The adrenal glands were denervated either by spinal cord transsection at the level of 0:7, or by division of the splanchnic nerves immediately below the diaphragm via the abdominal approach. Intraperitoneal barbi turate anaesthesia of short duration (Citodon-Na, Leo) was used. The rats were killed by decapitation.Inbred male ratsj 175-275 g , maintained on a diet of known composition, were used. During the acute experiment no food was given, but free access to water was allowed.Results. It was clearly shown that 2-DG, when administered in sufficiently high doses to maintain an elevated blood sugar level for a longer period of time, produces a marked increase in adrenaline secretion. Thus, when 2-DG was given in a dose of 50 mg per 100 g body weight twice over an 11 hour period, urinary adrenaline increased about 40 times (Table I) ; urinary noradrenaline excretion was doubled. Secretion of adrenal medullary hormones apparently was intense enough to make resynthesis lag behind, as revealed by pronounced lowering o...