Dynamics of insulin release and microtubular-microfilamentous system. II. Effect of vincristine.

In order to document the participation of microtubules in the dynamics of insulin release, the secretory response of the isolated perfused rat pancreas was measured after various times of exposure to vincristine (2.10-5M). After a short exposure time (25 min), both phases of glucose-induced insulin release were increased. After longer pretreatment (60 min), this facilitating effect disappeared and a slight, insignificant reduction of both phases of the secretory response to glucose was observed. A still longer exposure time (120 min) provoked a more marked and significant inhibition of the early and late phases of insulin release. The same enhancing effect after short pretreatment with vincristine was noticed when gliclazide was used as the insulinotropic agent. The ultrastructural studies indicated a progressive disappearance of microtubules concomitantly with an increase in number and size of vincristine-induced paracrystalline deposits. These findings suggest that microtubules indeed participate in the dynamics of insulin release, a reduction of both phases of insulin secretion being caused by an extended disruption of the microtubular apparatus, whereas a more limited disturbance of the microtubular system appears to be associated with facilitated insulin release in response to either glucose or sulfonylurea. © 1974 Springer-Verlag.In VitroJournal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe