حلزون باغي F77 اثرات سرب و آلومينيوم بر تحرك پذيري و ويژگي هاي بيوالكتريك سلول

The Effects of Lead and Aluminium on the Neuronal Excitability and Bioelectrical Characteristics of F77 Neuron in the Helix Aspersa

The effects of A13+ and Pb2+ were examined on the calcium spikes of Helix aspersa F77 neuron, using two microelectrode current clamp technique. These results show that in the normal Ringer, the action potential is sodium-calcium dependent. The important role of calcium ions in the depolarizing phase of the action potential was observable as long duration action potentials with a plateau, when Na+ and K+ ions were eliminated and sodium-potassium channel blockers were used. Nifedipine (1µM), a specific L-type calcium channel blaker, decreased action potential duration (P<0.01). Application of lead (0.6 and 3 µM) led to significant decrease in threshold and duration of action potential (P<0.05). The effects of lead were not dose dependent. Aluminum (150µM ) at pH between 6.8 to 6.9, affected excitability and bioelectrical characteristics of F77 neurons. The resting membrane potential, firing threshold, peak, amplitude, duration and frequency of action potentials were reduced significantly in the presence of aluminium. In summary, the results of this study demonstrate that lead and aluminum exert at least a part of their neurotoxic actions by alterning the neuronal excitability and action potential characteristics.