Abstract
Inhibition of motor responses to electrical presynaptic vagal stimulation by lowering the temperature of the bath fluid was studied using an isolated vagus-stomach preparation of the rat. The site of this cold block was investigated by comparing the response to a ganglionic stimulant drug and to acetylcholine with the response to nerve stimulation. Since in the temperature range between 25 and 22°C the preparation still responds to the former agents, the cold block is located at the ganglionic synaptic site and it is suggested that it may be due to a reduction in acetylcholine output at lower temperatures. Earlier observations on various preparations were also confirmed on the vagus-stomach preparation, showing that a low frequency of stimulation proved at lower temperatures to be more effective than a high frequency of stimulation. Barium was shown to markedly antagonize the cold block effects.
Footnotes
- Received June 5, 1962.
- Accepted November 19, 1962.
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