CRYOPRESERVATION OF ISOLATED RAT ISLETS OF LANGERHANS IN THE PRESENCEOF ETHYLENE-GLYCOL OR DIMETHYL-SULFOXIDE - EVALUATION OF TOXICITY ANDTHE DYNAMIC PATTERN OF SUBSEQUENT INSULIN RELEASE IN-VITRO

The toxic effect of ethylene glycol (EG) on the pattern of dynamic ins ulin release from rat pancreatic islets with or without freezing was i nvestigated in comparison with that of dimethyl sulfoxide (Me(2)SO). S ixty islets were perifused (1 ml/min) consecutively with D-glucose (1. 67 mM for 30 min followed by 16.7 mM for 60 min and 1.67 mM for 60 min ) after exposure to 2.0 M EG or Me(2)SO for 1 h at either 22 or 0 degr ees C. During the second period of perifusion, the insulin output from islets exposed to Me(2)SO or EG at 22 degrees C decreased to 53 and 5 1% of that from nontreated control islets, respectively. On the other hand, the islets exposed to EG at 0 degrees C exhibited 86% of the con trol insulin output under the same perifusion conditions, and this app eared to be higher than that of islets exposed to Me(2)SO (60%) at 0 d egrees C. Frozen islets, after exposure to 2.0 MEG or Me(2)SO for 1 h at 0 degrees C, responded positively to 16.7 mM D-glucose, and the typ ical biphasic pattern of insulin secretion was observed. The insulin o utput from these islets during the second period of perifusion was not comparable to that from unfrozen control islets. In particular, the m ean insulin output of EG-cryopreserved islets during the second period accounted for 99% of that from unfrozen control islets. The present f indings suggest the possible use of EG as an alternative cryoprotectan t to Me(2)SO. (C) 1996 Academic Press, Inc.