Intrasynaptosomal free calcium concentration during rat brain development: effects of hypoxia, aglycaemia, and ischaemia

Keelan, Julie and Bates, Timothy E. and Clark, John B. (1996) Intrasynaptosomal free calcium concentration during rat brain development: effects of hypoxia, aglycaemia, and ischaemia. Journal of neurochemistry, 66 (6). pp. 2460-7. ISSN 0022-3042

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Full text URL: http://dx.doi.org/10.1046/j.1471-4159.1996.6606246...

Abstract

The effects of hypoxia, aglycaemia, and hypoxia-aglycaemia on intrasynaptosomal free Ca2+ concentration ([Ca2+]i) have been investigated in rat brain synaptosomes prepared from animals aged 5, 10, 15, 20, 25, and 60 days. After 60 min of hypoxia there was no significant difference, when compared with controls, in basal [Ca2+]i or [Ca2+]i following depolarisation in all of the ages studied. Following 60 min of aglycaemia there was no significant difference from controls in [Ca2+]i of synaptosomes prepared from pups of < or = 20 days, although a significant rise in [Ca2+]i was seen in preparations from animals > 20 days old. Sixty minutes of hypoxia-aglycaemia led to a significant rise in [Ca2+]i only in preparations from animals 15-60 days old. With both aglycaemia and hypoxia-aglycaemia a progressive increase in the magnitude of the rise in [Ca2+]i was seen with development. These data suggest increases in [Ca2+]i in adult nerve terminals following prolonged aglycaemia and hypoxia-aglycaemia but no change following prolonged hypoxia. In contrast, no significant changes in [Ca2+]i values were apparent in neonatal nerve terminals under any of these conditions. In control synaptosomes with glucose and oxygen freely available, a decrease in resting and depolarised [Ca2+]i during development was seen, suggesting a change in calcium homeostasis within the nerve terminal as the brain develops. It is suggested that the mechanism underlying the relative resistance to ischaemic damage of neonatal brain as compared with adult brain may be related to the regulation of calcium at the nerve ending.

Item Type:Article
Additional Information:The effects of hypoxia, aglycaemia, and hypoxia-aglycaemia on intrasynaptosomal free Ca2+ concentration ([Ca2+]i) have been investigated in rat brain synaptosomes prepared from animals aged 5, 10, 15, 20, 25, and 60 days. After 60 min of hypoxia there was no significant difference, when compared with controls, in basal [Ca2+]i or [Ca2+]i following depolarisation in all of the ages studied. Following 60 min of aglycaemia there was no significant difference from controls in [Ca2+]i of synaptosomes prepared from pups of < or = 20 days, although a significant rise in [Ca2+]i was seen in preparations from animals > 20 days old. Sixty minutes of hypoxia-aglycaemia led to a significant rise in [Ca2+]i only in preparations from animals 15-60 days old. With both aglycaemia and hypoxia-aglycaemia a progressive increase in the magnitude of the rise in [Ca2+]i was seen with development. These data suggest increases in [Ca2+]i in adult nerve terminals following prolonged aglycaemia and hypoxia-aglycaemia but no change following prolonged hypoxia. In contrast, no significant changes in [Ca2+]i values were apparent in neonatal nerve terminals under any of these conditions. In control synaptosomes with glucose and oxygen freely available, a decrease in resting and depolarised [Ca2+]i during development was seen, suggesting a change in calcium homeostasis within the nerve terminal as the brain develops. It is suggested that the mechanism underlying the relative resistance to ischaemic damage of neonatal brain as compared with adult brain may be related to the regulation of calcium at the nerve ending.
Keywords:Synaptosomes, Calcium, Ca2+, Brain, Development, hypoxia, aglycemia
Subjects:A Medicine and Dentistry > A100 Pre-clinical Medicine
B Subjects allied to Medicine > B140 Neuroscience
C Biological Sciences > C141 Developmental Biology
Divisions:College of Science > School of Life Sciences
ID Code:5324
Deposited By: Timothy Bates
Deposited On:22 May 2012 08:18
Last Modified:22 May 2012 08:18

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