Evidence for selective release of rodent islet amyloid polypeptide through the constitutive secretory pathway.

To determine the potential for differential release of islet amyloid polypeptide and insulin, we performed studies in rat islet monolayer cultures under conditions known to impair regulated beta-cell secretion. In inhibiting concentrations of epinephrine or the absence of calcium, islet amyloid polypeptide was secreted through a constitutive pathway while insulin was not. These findings suggest a mechanism for persistent islet amyloid polypeptide secretion and amyloid accumulation when regulated insulin release is impaired as in Type 2 (non-insulin-dependent) diabetes mellitus and insulinomas.