A rise in the intracellular Ca2+ concentration of isolated rat supraoptic cells in response to oxytocin.
AUTOR(ES)
Lambert, R C
RESUMO
1. Intracellular Ca2+ concentration ([Ca2+]i) was monitored in single cells isolated from adult rat supraoptic (SO) nuclei. The great majority of cells (85%) were neurones and most were immunoreactive to oxytocin or to vasopressin (AVP). 2. The resting [Ca2+]i of the majority (80%) of the neurones remained stable while 20% of the neurones displayed spontaneous [Ca2+]i oscillations which disappeared in low-Ca2+ (100 nM) EGTA buffer. 3. Addition of 100 nM oxytocin increased the [Ca2+]i in both stable and oscillating cells. Two types of responses were observed: (i) a sustained response with [Ca2+]i being maintained at an elevated level and (ii) a brief response with [Ca2+]i quickly returning to a near-resting level. Responses were reproducible, dose dependent and blocked with a specific oxytocin antagonist. 4. Removal of extracellular Ca2+ did not block the oxytocin response. In EGTA buffer, application of thapsigargin (200 nM) onto oxytocin-sensitive cells induced an increase in [Ca2+]i and inhibited the oxytocin response. These effects were not induced by other intracellular Ca2+ mobilizers such as tBuBHQ (see Methods) or caffeine. 5. In conclusion, half of the SO cells respond to oxytocin with a rise in [Ca2+]i. The effect is mediated by oxytocin receptors and results from release of Ca2+ from thapsigargin-sensitive stores.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1155685Documentos Relacionados
- Vasopressin-induced intracellular Ca2+ increase in isolated rat supraoptic cells.
- ATP stimulates Ca2+ uptake and increases the free Ca2+ concentration in isolated rat liver nuclei.
- Critical intracellular Ca2+ concentration for all-or-none Ca2+ spiking in single smooth muscle cells.
- Ca2+ and Sr2+ entry induced Ca2+ release from the intracellular Ca2+ store in smooth muscle cells of rat portal vein.
- Regulation of the cytosolic Ca2+ concentration by Ca2+ stores in single smooth muscle cells from rat cerebral arteries.