Development of an in vitro model using calcium imaging to investigate antidotal efficacy against saxitoxin. Report September 1994-September 1996
Studies were conducted to investigate the utility of a novel in vitro system to monitor the efficacy of potential antidotes against sodium channel neurotoxins. Intracellular free calcium levels were measured in PC-12 (rat adrenal pheochromocytoma) cells utilizing a calcium imaging system with Fura-2 as the ratiometric calcium-sensitive indicator. Elevations in Ca(++) induced by high extracellular potassium (K(+)) and 4-aminopyridine (4-AP) were demonstrated, thus confirming the responsiveness of the system. Saxitoxin (STX), however, did not produce any alteration in Ca(++), perhaps due to a relatively low level of neuronal activity, i.e., impulse generation, in the in vitro state. Therefore, we attempted to activate PC-12 cells using the sodium channel agonist veratridine (VER) to determine whether STX could reduce enhanced Ca(++) levels. Although VER generally increased Ca(++), this response was somewhat variable and thus could not be used to demonstrate STX-induced toxic effects. Such variability may be inherent to cell lines; thus, the use of primary cultures is recommended to develop an in vitro system using Ca(++) levels as an endpoint to evaluate the efficacy of antidotes against sodium channel toxins.
- Research Organization:
- Army Medical Research Inst. of Chemical Defense, Aberdeen Proving Ground, MD (United States)
- OSTI ID:
- 562742
- Report Number(s):
- AD-A-328112/8/XAB; TRN: 80050058
- Resource Relation:
- Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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