Effect of in vitro inorganic lead on dopamine release from superfused rat striatal synaptosomes
The effect of inorganic lead in vitro in several aspects of (/sup 3/H)dopamine release from superfused rat striatal synaptosomes was examined. Under conditions of spontaneous release, lead (1-30 microM) induced dopamine release in a concentration-dependent manner. The onset of the lead-induced release was delayed by approximately 15-30 sec. The magnitude of dopamine release induced by lead was increased when calcium was removed from the superfusing buffer. Lead-induced release was unaffected in the presence of putative calcium, sodium, and/or potassium channel blockers (nickel, tetrodotoxin, tetraethylammonium, respectively). Depolarization-evoked dopamine release, produced by a 1-sec exposure to 61 mM potassium, was diminished at calcium concentrations below 0.254 mM. The onset of depolarization-evoked release was essentially immediate following exposure of the synaptosomes to high potassium. The combination of lead (3 or 10 microM) with high potassium reduced the magnitude of depolarization-evoked dopamine release. This depression of depolarization-evoked release by lead was greater in the presence of 0.25 mM than 2.54 mM calcium in the superfusing buffer. These findings demonstrate multiple actions of lead on synaptosomal dopamine release. Lead can induce dopamine release by yet unidentified neuronal mechanisms independent of external calcium. Lead can also reduce depolarization-evoked dopamine release by apparent competition with calcium influx at the neuronal membrane calcium channel.
- Research Organization:
- Univ. of Cincinnati, OH
- OSTI ID:
- 5268603
- Journal Information:
- Toxicol. Appl. Pharmacol.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
DOPAMINE
SECRETION
LEAD
BIOLOGICAL EFFECTS
CALCIUM
IN VITRO
NERVE CELLS
POTASSIUM
RATS
TRITIUM COMPOUNDS
ALKALI METALS
ALKALINE EARTH METALS
AMINES
ANIMAL CELLS
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DRUGS
ELEMENTS
HYDROXY COMPOUNDS
LABELLED COMPOUNDS
MAMMALS
METALS
NEUROREGULATORS
ORGANIC COMPOUNDS
PHENOLS
POLYPHENOLS
RODENTS
SOMATIC CELLS
SYMPATHOMIMETICS
VERTEBRATES
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)
550201 - Biochemistry- Tracer Techniques