[The maintenance of insulin secretory response of long-term cultured pancreatic islets to glucose, acetylcholine and epinephrine (author's transl)].

The present study was performed to investigate whether long-term cultured rat pancreatic islets possess a postcultural insulin secretory response to hormones and neurotransmitters in spite of their lack of stimulation during the culture period. We also investigated the method of maintaining the insulin secretory response of islets cultured in a physiological concentration of glucose. The tissue culture media were TCM 199 supplemented with 5.5 mM glucose (A medium), 5.5 mM glucose plus 1 mM adenosine (B medium), 16.7 mM glucose (C medium), and 16.7 mM glucose plus 1 mM adenosine (D medium). Short-term incubation after the culture period of 14 days showed that the islets cultured in B, C and D media maintained the same insulin secretory responsiveness to 8.3 mM glucose and/or 5 microM acetylcholine and also to 1 microM epinephrine as did non-cultured islets. A similar response was found among the islets maintained in B, C and D media. An insulin secretory response to epinephrine and phentolamine was deficient in islets cultured in A medium, whereas it was maintained in those cultured in C medium. The responsiveness of the islets cultured in C medium to the concomitant stimulation by epinephrine and phentolamine was not different from that of the non-cultured islets. It was thus concluded that the addition of adenosine in the culture medium containing the physiological concentration of glucose was as effective in amintaining the insulin secretory ability of the islets as was the culture medium containing a high concentration of glucose, and it was suggested that even the pancreatic islets cultured in these media, though separated from the innervation might preserve acetylcholine and adrenergic receptors similar to freshly isolated islets. Considering the action of adenosine, the necessity of enhancing ATP and C-AMP concentrations in B cells was also suggested in order to maintain the insulin secretory ability of cultured pancreatic islets.