Research of generation of respiratory rhythm

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The three neurons that comprise the respiratory central pattern generator in the brain of the snail. Lymnaea stagnalis were examined to elucidate their function. When an hypoxic saline solution was perfused over an isolated brain preparation (i.e., without peripherally nerves), respiratory activity remained unchanged When an hypoxic saline solution was perfused over a semi-intact brain preparation (i.e., peripherally nerves still connected), respiratory activity increased.The Right Peda1 Dorsal I respiratory neuron (RPeD1, that initiates respiratory activity) was then isolated and cultured Perfusion with an hypoxic saline solution produced no change in either the resting membrane or action potentials, suggesting that RPeD1 does not exhibit oxygen chemoreception.To locate and isolate the oxygen chemoreceptor, an attempt was made to separate and culture the neurons of the osphradium ganglion, which lies immediately beneath the pneumostome. All attempts thus far have been unsuccessful.The effects of carbon dioxide on both the isolated and semi-intact brain preparations were also examined by perfusing them with a saline solution equilibrated with a 5% C02/95% 02 gas mixture. Respiratory activity decreased in both preparations.The saline solution used in the experiment above also had a low pH.In an effort to distinguish the effects of pH from the presence of C02, both preparations were perfused with a saline solution equilibrated with 21%02+79%N02 and whose pH had been adjusted with HCl to a pH of 7.0-7.5. Respiratory activity was decreased in both preparations as well.