Abstract— Synaptosomes prepared by differential and Ficoll density gradient centrifugation took up d‐galactose by two saturable transport systems: one. a high affinity system with a Km of 0‐25 mn and Vmax of 075 nmol/mg protein 3 min, the other, a low affinity system with a Km of 47 mM and a Vmaxof 135 nmol/mg protein/3 min. The high affinity system was inhibited by 1‐5 mM phlorizin but was unaffected by the absence of sodium ion or the presence of 1 mM ouabain. The low affinity system was unaffected by phlorizin or ouabain. Both systems were inhibited by high concentrations of glucose. 2‐deoxyga‐lactose. and inositol, and by 2.4‐dinitrophcnol. Galactose was rapidly converted in synaptosomes to phos‐phorylatcd intermediates and was more slowly oxidized to 14CO2

Six men with prolactin-secreting pituitary macroadenomas and deficiencies of pituitary hormones other than gonadotrophins were treated with bromocriptine for 6 months. During treatment the serum prolactin concentration decreased markedly in all six patients, and in four adenoma size decreased and visual function improved. Two patients who were hypothyroid before bromocriptine treatment were euthyroid during the sixth month of treatment, and the one patient who was hypoadrenal before treatment was euadrenal during treatment. Two of the six men who had subnormal growth hormone secretion before treatment had normal growth hormone secretion during treatment. We conclude that pituitary hormonal functions may improve during bromocriptine treatment for prolactin-secreting pituitary macroadenomas. This improvement may result from decompression of other pituitary cells, because correction of hypothyroidism by bromocriptine was accompanied by conversion from an absent to a normal thyrotrophin response to thyrotrophin-releasing hormone.

The uptake of inositol by rat brain synaptosomes occurs via an unsaturable process that even at substrate concentrations as low as 1 μM is unable to achieve a concentration gradient indicative of active transport. Dinitrophenol, ouabain and cytochalasin B did not affect uptake of the cyclitol. The data indicate that inositol uptake by rat synaptosomes occurs by diffusion or by a system with an affinity so low it is difficult to discern. The low capacity, saturable inositol uptake system observed in rabbit brain slices may reflect a species difference or uptake by elements of the slice other than neuronal membranes.