抄録
Tris (hydroxymethyl) aminomethane (Tris) has been shown to inhibit selectively the Golgi apparatus and Golgi-endoplasmic reticulum-lysosomal system (GERL system) of several kinds of cells including pancreatic B cells. The present study was undertaken to assess the effect of Tris on insulin release and synthesis in pancreatic B cells.
Islets isolated from male Wistar rats by the collagenase method were incubated for 60 min at 37°C under 95% O2-5% CO2. In the presence of 8.3 mM glucose, the insulin secretion was 3.45±0.19 neislet·60 min. However, addition of 1 and 10 mM Tris reduced the insulin release to 2.33±0.31 and 1.27±0.19 neislet·60 min, respectively. Furthermore, the incorporation of 3H-leucine into the immunoreactive proinsulin and insulin fraction was lowered in the presence of 10 mM Tris compared to that in its absence in 2-hr incubation studies. The ratio of the radioactivity of the immunoreactive insulin fraction to the sum of that of the immunoreactive proinsulin and insulin fraction was reduced by 10 mM Tris.
Thus, Tris inhibited not only insulin secretion but also the conversion from proinsulin to insulin. The present study suggests that the Golgi apparatus and GERL system may play a role in insulin secretion and biosynthesis in pancreatic B cells, and that Tris may represent a useful agent for investigating the mechanism of conversion from proinsulin to insulin.
