Rc. Ruhe et al., STIMULUS-SECRETION COUPLING AND INSULIN-SECRETION IN AGING - EVALUATION OF GLUCOSE-OXIDATION AND ATP-SENSITIVE POTASSIUM CHANNEL RESPONSIVENESS, Mechanism of ageing and development, 71(3), 1993, pp. 161-167
The purpose of this study was to evaluate possible age-related alterat
ions in the glucose-stimulus/insulin-secretion coupling mechanism of i
slets of Langerhans. To this end, the interaction among insulin secret
ion, glucose oxidation, and ATP-sensitive potassium (K-ATP) channel re
sponsiveness was determined in islets of Langerhans isolated from 6-,
12-, and 26-month-old male Fischer 344 (F344) rats. Groups of 20 islet
s were incubated for 40 min at 37 degrees C in a buffer containing: (1
) either 1.7 or 11.1 mM glucose; (2) 1.2 mu M glyburide and either 1.7
or 11.1 mM glucose; (3) 5 mu M epinephrine and 11.1 mM glucose; or (4
) 1.2. mu M glyburide, 5 mu M epinephrine, and either 1.7 or 11.1 mM g
lucose. Insulin release of islets incubated in the presence of glyburi
de and 1.7 or 11.1 mM glucose was greater than that of islets incubate
d in glucose alone, while glucose oxidation did not increase. Epinephr
ine inhibited insulin release and glucose oxidation at 11.1 mM glucose
and abolished glyburide-enhanced insulin release at 11.1 mM glucose.
No effect of age was observed in any of the treatment categories. Thes
e results indicate that if age-related alterations are occurring in gl
ucose-stimulus/insulin-secretion coupling, then such alterations are n
ot associated with changes in K-ATP channel-mediated responsiveness.