Insulin processing by cultured hepatocytes
Blackard, W.G.; Smith, R.M.; Jarett, L.
American Journal of Physiology 250(2 Pt 1): E148-E155
1986
ISSN/ISBN: 0002-9513 PMID: 3513607 Document Number: 272225
The chloroquine-sensitive and chloroquine-insensitive steps in insulin degradation by cultured hepatocytes have been explored by employing low temperature to retard processing. Under the standard conditions (90 min association and 60 min dissociation) chloroquine inhibited insulin degradation at 15.degree. C but not at 37.degree. C. However, if the association and dissociation periods were short so that only early degradation was examined, marked inhibition of insulin degradation by chloroquine could also be observed at 37.degree. C. This inhibitory effect was observed only during the first 15 min, being masked by increased insulin degradation subsequently. An increase in slowly dissociable insulin, as well as a twofold increase in volume density of multivesicular bodies (MVB), occurred in the presence of chloroquine at both 37 and 15.degree. C. Rapid insulin processing from the slowly dissociable compartment of 37.degree. C masked chloroquine's effect on insulin processing under usual conditions at that temperature. At physiological temperature the chloroquine-sensitive step is not obligatory for insulin degradation by hepatocytes.