[The effect of ascorbic acid on adrenergic lipolysis]

The effect of ascorbic acid on basal and adrenergic lipolysis was studied in rat epididymal adipose tissue in vitro. When adipose tissue was incubated with isoprenaline (ISO) for 1.5 h, the concentration-lipolytic effect curves of ISO were practically the same in the presence or absence of ascorbic acid used in concentration 100 and 1000 micrograms/ml. The lipolytic effect of ISO was not substantially altered even in the experiments in which adipose tissue was incubated with ISO for 4.5 h, but ascorbic acid (1000 micrograms/ml) was added only 1.5 h before the end of incubation. On the other hand, the contact of adipose tissue for 4.5 h with high concentration of ascorbic acid (1000 micrograms/ml) induced significant decrease of maximum adipokinetic effect of ISO. Contrary to catecholamine stimulated lipolysis, the basal rate of lipolysis was enhanced by ascorbic acid. Inhibition of maximum lipolytic effect of catecholamines (isoprenaline and noradrenaline-NOR) and oxedrine (isopropylnoroxedrine) was also seen when adrenomimetics were added to incubation medium 1.5 h before the end of 4.5 h incubation of adipose tissue with ascorbic acid. Decreased reactivity of adipose tissue to catecholamines persisted when the tissue, after 3 h incubation with ascorbic, was transferred into fresh medium with ISO and ascorbic acid. Preincubation of ascorbic acid (3h) in the incubation medium without adipose tissue, followed by subsequent addition of the tissue and catecholamines (NOR, ISO) and 1.5 h lasting incubation, did not influence the adipokinetic effect of NOR and ISO. These facts indicate that ascorbic acid decreases the lipolytic effect of catecholamines as a result of its effect on adipose tissue but not on the incubation medium.(ABSTRACT TRUNCATED AT 250 WORDS)