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KMID : 0351619710120010125
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Kyungpook Medical Journal
1971 Volume.12 No. 1 p.125 ~ p.137
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Maximum Cardiovascular Responses Elicited by Different Frequencies of Electrical Stimulation Applied to Cervical Vagal Nerve in the Dog
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Abstract
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In order to study the changes in the central venous pressure, arterial blood pressure ar.~d heart rate, the efferent ending of the cervica], vagus nerve in dogs was electrically stimulated (1V: lmsec. pulse duration) for the period of 1/2, 1, 2, 3 and 5 minutes and also an attempting was made to determine the maximum cardiovascular responses and response decay phenomena in relativel}* long period (5min.) by different el~:ctrical frequencies of stimulation.
The results obtained are summarized a:~ follows:
1. The stimulation of the efferent vagal, nerve with the effective stimulation always resulted in the negative chronotropic responses, and the cycles to elicit the maximum negative chronotropic action were:
20 c. p. s-60.9% of total cases, and t 60 c. p. s-30.4% of total cases in right ~vagal stimulation.
20 c. p. s-53.6% of total cases, and
60 c. p.s-28.6 % of total cases in left vagal stimulation.
2. The stimulation of the efferent vagal nervewith the effective stimulation always produced the pressure decrease responses.
The frequencies to elicit the maximum blood pressure responses were:
20 c. p. s-67.7%, and 60 c. p. s-21.4% in right vagal stimulation.
20 c. p. s-46.6%, and 60 c. p. s-16.7% in left. vagal stimulation.
3. The stimulation of the efferent vagal nerve with the effective stimulation always induced. increased response in the central venous pressure.
The frequencies to produce the maximum central venous pressure responses were:
20 c. p. s-73.3%, and 60 c. p. s-26.7% in right. vagal stimulation.
20 c. p. s-48.2%, and 60 c. p. s-37.9% in left vagal stimulation.
4. The cardiovascular response in the stimulation for 5 minutes was decreased comparing withthat of the initial level.
The reason for the decrease may be due to the response decay phenomea and inappropriate release of chemical transmitter in the neural mechanism.
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