EFFECTS OF PULSATILE GLUCOSE STIMULI ON LONG-TERM INSULIN SECRETORY PATTERNS IN ISLETS OF LANGERHANS MICRODISSECTED FROM SYRIAN-HAMSTERS

The long-term effects of continuous and pulsatile glucose stimulation of islets of Langerhans microdissected from Syrian hamsters were exami ned. In the presence of a continuous glucose stimulus insulin secretio n peaked during the first 3 h of stimulation followed by a decrease. I n the presence of 11.2 mM glucose a second smaller peak of insulin sec retion was observed 14-16 h after the perifusion started. Irrespective of the glucose concentration, insulin secretion then steadily decreas ed and reached very low levels by the end of the 48-h perifusion. Howe ver, glucose stimulus provided in a pulsatile manner appeared to reduc e this rate of decrease in insulin secretion. Thus, after 48 h, islets exposed to the pulsatile glucose stimulus showed greater insulin resp onsiveness to glucose than those exposed to a constant glucose stimulu s.