Membrane Retrieval after Immediately Releasable Pool (IRP) Exocytosis is produced by Dynamin-Dependent and Dynamin-Independent/Protein Kinase C-Dependent Mechanisms

BAYONÉS, LUCAS; SAMUEL ALFONSO-BUENO; MONTENEGRO, MAURICIO; MOYA-DÍAZ, JOSÉ; CASPE, OCTAVIO; GALLO, LUCIANA I.; FERNANDO D. MARENGO

JOURNAL OF NEUROCHEMISTRY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

0022-3042

The importance of the immediately releasable pool (IRP) of vesicles was proposed to reside in the maintenance of chromaffin cell secretion during the firing of action potentials at basal physiological frequencies. To accomplish this duty, IRP should be replenished as a function of time. We have previously reported that an action potential-like stimulus (APls) triggers the release of ~50% IRP, followed by a fast dynamin-dependent endocytosis and an associated rapid replenishment process. In this work we investigated the endocytosis and IRP replenishment produced after the exocytosis of variable IRP fractions in mice primary chromaffin cell cultures. Exocytosis and endocytosis were estimated by membrane capacitance measurements obtained in patch-clamped cells. In addition to the dynamin-dependent fast endocytosis activated after the application of APls or 5 ms squared depolarizations, we found that depolarizations lasting 25-50 ms, which release >80% of IRP, are related with a fast dynamin-independent, Ca2+- and protein kinase C (PKC)-dependent endocytosis (time constant