Date of Award
Summer 1996
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Program/Concentration
Biomedical Sciences
Committee Director
Dieter K. Bartschat
Committee Member
Peter F. Blackmore
Committee Member
barbara Y. Hargrave
Committee Member
Gerald J. Pepe
Committee Member
Paul H. Ratz
Abstract
Low level lead (Pb2+) exposure may produce lasting deficits in learning and memory by altering calcium (Ca2+) dependent processes. Isolated presynaptic nerve terminals from rat hippocampus were loaded with the intracellular (Ca2+) indicator Fura-2. The changes in cytoplasmic free calcium ([Ca2+]i) were measured by stopped-flow fluorescence spectroscopy following depolarization with elevated potassium on a millisecond time scale (Lentzner et al., 1992). Depolarization promoted a rapid increase in Ca2+i which occured in two kinetically distinguishable phases: a fast component, representing the activity of rapidly inactivating Ca2+ channels (τ ~ 60 msec), and a slow component, which is comprised of slowly inactivating Ca2+ channels (τ ~ 1sec) and Na+/Ca2+ exchange operating in the "reverse" mode. Low concentrations of Pb2+ (0.1-0.5 μΜ ) blocked competitively both the rapidly and slowly inactivating channels. At higher concentrations (≥1μΜ) , Pb2+ permeated the rapidly inactivating channels. Pb2+ permeation was accompanied by a subsequent rise in intracellular Ca2+ even in the absence of extracellular Ca2+. The rise in Ca2+ was reduced by thapsigargin, suggesting Pb2+ activates the release of Ca2+ from intracellular stores, possibly an IP3 sensitive store. The Ca2+ release was greatest in younger animals and gradually declined during postnatal development.
DOI
10.25777/sj0e-0275
ISBN
9780591048674
Recommended Citation
Rhodes, Troy E..
"Lead Activation of a Developmentally Regulated Calcium Channel in Rat Hippocampal Nerve Terminals"
(1996). Doctor of Philosophy (PhD), Dissertation, , Old Dominion University, DOI: 10.25777/sj0e-0275
https://digitalcommons.odu.edu/biomedicalsciences_etds/72
Comments
A dIssertation Submitted to the Faculty of Old Dominion University and Eastern Virginia Medical School in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy in Biomedical Sciences.