Key result
Anesthesia selectively suppresses cardiac and renal sympathetic test responses during paired uvular stimulation.
Why the study?
The sympathetic mechanisms converting the tachycardia-pressor response to cerebellar uvula stimulation in unanesthetized decerebrate cats into a bradycardia-depressor response under anesthesia required investigation.
Does anesthesia alter the sympathetic nerve responses evoked by electrical stimulation of the cerebellar uvula in decerebrate cats?
Does anesthesia alter the sympathetic nerve responses evoked by electrical stimulation of the cerebellar uvula in decerebrate cats?
In decerebrate cats, anesthesia converts the cardiovascular response to cerebellar uvula stimulation from tachycardia-pressor to bradycardia-depressor by augmenting sympathoinhibitory processes rather than blocking sympathoexcitation.
Answers are grounded in this paper and cite their sources.
Anesthesia reverses uvula-evoked autonomic responses in cats; leaves open translation to human cardiovascular regulation.
The sympathetic mechanisms involved in the conversion of the tachycardia-pressor response evoked by electrical stimulation of the uvula (lobule IX of the posterior cerebellar cortex) in the unanesthetized decerebrate cat to a bradycardia-depressor response in the same, but anesthetized preparation, were investigated. Sympathoexcitation was produced in the inferior cardiac and renal sympathetic nerves in response to short train stimulation (2-5 pulses, 100-500 Hz) of the uvula in the unanesthetized decerebrate cat, and when paired stimuli (conditioning and test) were applied, the test-evoked potential in both nerves was similar to the response elicited by the conditioning stimulus. Anesthetic administered to these same animals caused the test response in both sympathetic nerves to be greatly decreased, yet the conditioning response was unchanged. The attenuation of the test response by the conditioning stimulus diminished during recovery from anesthesia. The recovery of the test response paralleled the time course of the return of the tachycardia-pressor effect evoked by long train stimulation of the uvula. It appears that anesthesia does not block the sympathoexcitatory response but acts to augment sympathoinhibitory processes associated with uvula stimulation; some possible mechanisms are discussed.
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Paton et al. (1992) studied Sympathetic responses to cerebellar uvula stimulation in decerebrate cats. Anesthetic administration during paired electrical stimulation (2-5 pulses, 100-500 Hz) of the cerebellar uvula vs. Unanesthetized state in the same decerebrate cats was evaluated on Test-evoked and conditioning-evoked potentials in the inferior cardiac and renal sympathetic nerves. Anesthetic administration during paired uvula stimulation (2-5 pulses, 100-500 Hz) greatly decreased the test response in cardiac and renal sympathetic nerves while leaving the conditioning response unchanged.
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