Effect of TEA and 4-AP on Primary Sensory Neurons in a Crustacean Model

Background and Objective: Pharmacological agents 4-aminopyridine (4-AP) and tetraethylammonium chloride (TEA) block different subsets of voltage-gated potassium (K+) channels. The potassium channels in the chordotonal organs in crab limbs are sensitive to both blockers. These organs serve as a model of proprioceptive sensation and have rapidly and slowly-adapting sensory neurons. Since 4-AP is used clinically in the treatment of amyotrophic lateral sclerosis and multiple sclerosis, a better understanding of its action on proprioceptive models will increase our knowledge of the potential effects in mammalian systems. Materials and Methods: To assess the action of these blockers on the function of proprioceptive sensory neurons, the neurons were evoked by movements associated with the joint while applying these compounds individually or in combination. The model organism was the blue crab (Callinectes sapidus). Results: Both 4-AP and TEA individually and in combination decreased the activity of evoked compound action potentials in isolated nerves. Conclusion: The blockers appeared to act on electrical induction and conduction within the axons, suggesting that the crab limb proprioceptive organs can be used as a model for future pharmacological investigations to increase our understanding of mechanosensitive channels and neuronal activity.