Evidence for a Na+/Ca2+ exchange mechanism in the neuroendocrine cells of the locust corpus cardiacum

Tom Pannabecker, Ian Orchard

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The glandular lobe of the locust corpus cardiacum (CC) is a peripheral neuroendocrine gland consisting primarily of neurosecretory cells (NSCs), all of which synthesize, store, and release adipokinetic hormones (AKHs). An influx of extracellular Ca2+ into the NSCs provides an essential trigger for initiating AKH release. In this study we demonstrate that the Na+ gradient across the plasma membrane of these NSCs has a significant influence on the process of AKH release and on Ca2+ fluxes across the membrane. AKHs are released from NSCs when the corpus cardiacum is incubated in Na+-free saline or in K+-free saline with ouabain. The rate of 45Ca2+ efflux from the gland is reduced by 50% when glands are incubated in Na+-free saline compared to normal saline. The amount of 45Ca2+ uptake by Na+-loaded cells is nearly 100% greater in glands exposed to Na+-free saline compared to glands in normal saline. These results are most clearly interpreted by proposing that a Na+/Ca2+ exchange system is present in the NSCs. This system may provide an essential Ca2+ buffering mechanism by extruding Ca2+ from the NSCs following a stimulus-secretion cycle.

Original languageEnglish (US)
Pages (from-to)180-184
Number of pages5
JournalBrain Research
Volume458
Issue number1
DOIs
StatePublished - Aug 16 1988

Keywords

  • Adipokinetic hormone
  • Calcium
  • Corpus cardiacum
  • Insect
  • Locust
  • Neuroendocrine
  • Sodium-calcium exchange

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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