Earthworm Action Potential Conduction Velocity:
The Effects of Various Salts and Neurotransmitters
When it comes to performing action potential experiments within the lab, the giant nerve fibers of an earthworm are an important tool for success. They yield a high success rate when compared to other organisms (Kladt, Hanslik, & Heinzel, 2010), and provide a more ethical means of testing how various neurotransmitters affect action potentials, instead of direct use on humans for pharmaceutical purposes. However, other than their usefulness in the lab, they are also an important contributor to ecosystems. Earthworms are known for their abilities as ecosystem engineers to break down organic material and mix the nutrients from this material throughout …show more content…
To avoid interference, we set up in a room with as few other computers as possible, and we set a noise filter within the program with the low cutoff value of 65Hz, and the high cutoff value of 10,000 Hz. Our solutions were prepared in advance, and were made from stock solutions diluted with appropriate amounts of distilled water to reach the desired concentration, as calculated by M_i V_i=M_f V_f, where Mi is initial stock molarity, Mf is the desired concentration of 0.00001M, and where Vi is the initial volume of stock solution used, and Vf is the total volume after dilution with distilled water. We made a surplus volume of what was to be injected, in case we did not see an effect with the 0.1mL dose. We selected the dose of 0.1mL based on a trial injection of 0.3mL of sodium chloride, which was too much fluid and caused the worm to swell excessively and killed it, but found that the volume of 0.1mL of sodium chloride only caused minor swelling, and that the worm survived the injection. In our experiment, we used a separate earthworm for each solution that we prepared for testing. Each earthworm was first anesthetized in a 10% ethanol bath and then dried off, followed by making recordings of their action potentials across a ten second span of time. The stimulus amplitude within the software was adjusted to the threshold level at which it produced an action potential in the worms ("Action Potentials in Earthworm-Lab," 2013), which was found at 0.5 volts. These initial recordings were done to be used as controls for calculating the conduction velocities prior to any injections we made, therefore we would be able to see if there was an alteration in how each particular individual’s conduction velocity was affected. The earthworms were then anesthetized a second time, and injected with their designated solutions. Between uses, the syringe was rinsed very thoroughly
The Effects of Various Salts and Neurotransmitters
When it comes to performing action potential experiments within the lab, the giant nerve fibers of an earthworm are an important tool for success. They yield a high success rate when compared to other organisms (Kladt, Hanslik, & Heinzel, 2010), and provide a more ethical means of testing how various neurotransmitters affect action potentials, instead of direct use on humans for pharmaceutical purposes. However, other than their usefulness in the lab, they are also an important contributor to ecosystems. Earthworms are known for their abilities as ecosystem engineers to break down organic material and mix the nutrients from this material throughout …show more content…
To avoid interference, we set up in a room with as few other computers as possible, and we set a noise filter within the program with the low cutoff value of 65Hz, and the high cutoff value of 10,000 Hz. Our solutions were prepared in advance, and were made from stock solutions diluted with appropriate amounts of distilled water to reach the desired concentration, as calculated by M_i V_i=M_f V_f, where Mi is initial stock molarity, Mf is the desired concentration of 0.00001M, and where Vi is the initial volume of stock solution used, and Vf is the total volume after dilution with distilled water. We made a surplus volume of what was to be injected, in case we did not see an effect with the 0.1mL dose. We selected the dose of 0.1mL based on a trial injection of 0.3mL of sodium chloride, which was too much fluid and caused the worm to swell excessively and killed it, but found that the volume of 0.1mL of sodium chloride only caused minor swelling, and that the worm survived the injection. In our experiment, we used a separate earthworm for each solution that we prepared for testing. Each earthworm was first anesthetized in a 10% ethanol bath and then dried off, followed by making recordings of their action potentials across a ten second span of time. The stimulus amplitude within the software was adjusted to the threshold level at which it produced an action potential in the worms ("Action Potentials in Earthworm-Lab," 2013), which was found at 0.5 volts. These initial recordings were done to be used as controls for calculating the conduction velocities prior to any injections we made, therefore we would be able to see if there was an alteration in how each particular individual’s conduction velocity was affected. The earthworms were then anesthetized a second time, and injected with their designated solutions. Between uses, the syringe was rinsed very thoroughly