Logo image
Back
Secretion from rat neurohypophysial nerve terminals (neurosecretosomes) rapidly inactivates despite continued elevation of intracellular Ca 2
Journal article   Peer reviewed

Secretion from rat neurohypophysial nerve terminals (neurosecretosomes) rapidly inactivates despite continued elevation of intracellular Ca 2

Alessandro Fatatis, Lynne Holtzclaw, Kemal Payza and James T. Russell
Brain research, v 574(1), pp 33-41
1992
DOI: https://doi.org/10.1016/0006-8993(92)90796-C
Featured in Collection :   UN Sustainable Development Goals @ Drexel

Abstract

Calcium imaging Cytoplasmic free calcium Nerve terminal Neurohypophysis Neurosecretosome
Cytoplasmic calcium concentration was measured in neurosecretory nerve terminals (neurosecretosomes) isolated from rat neurohypophyses by fura-2 fluorescence measurements and digital video microscopy. Hormone release and cytoplasmic calcium concentration were measured during depolarizations induced by elevated extracellular potassium concentration. During prolonged depolarizations with 55 mM [K +] 0, the cytoplasmic calcium concentration remained elevated as long as depolarization persisted, while secretion inactivated after the initial sharp rise. The amplitude and duration of the increase in [Ca 2+] i was dependent on the degree of depolarization such that upon low levels of depolarizations (12.5 mM or 25 mM [K +] 0), the calcium responses were smaller and relatively transient, and with higher levels of depolarization (55 mM [K +] 0) the responses were sustained and were higher in amplitude. Responses to low levels of depolarization were less sensitive to the dihydropyridine calcium channel blocker, nimodipine, while the increase in [Ca 2+] i induced by 55 mM [K +] 0 became transient, and was significantly smaller. These observations suggest that these peptidergic nerve terminals possess at least two different types of voltage-gated calcium channels. Removal of extracellular sodium resulted in a significant increase in [Ca 2+] i and secretion in the absence of depolarizing stimulus, suggesting that sodium-calcium exchange mechanism is operative in these nerve terminals. Although the [Ca 2+] i increase was of similar magnitude to the depolarization-induced changes, the resultant secretion was 10-fold lower, but the rate of inactivation of secretion, however, was comparable.

Metrics

5 Record Views
11 citations in Web of Science
10 citations in Scopus

Details

UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#3 Good Health and Well-Being

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Neurosciences
Logo image