Intravenous Dexmedetomidine Inhibits Cerebrovascular Dilation Induced by Isoflurane and Sevoflurane in Dogs

Ohata, Hiroto; Iida, Hiroki; Dohi, Shuji; Watanabe, Yukinaga

doi:10.1097/00000539-199908000-00023

Cited by 37 publications

(37 citation statements)

References 25 publications

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“…CBF reduction and pial vessel constriction induced by DEX have been well documented for various species. Whereas the cerebral vasoconstriction is mediated by direct agonist binding to α 2 ‐adrenergic receptors on the cerebral vessels (Nakai et al ., ), the degree of vasoconstriction depends on the dose, the delivery method (topical vs. systemic), and anesthetics used prior to DEX administration (Karlsson et al ., ; Zornow et al ., ; Bari et al ., ; Fale et al ., ; McPherson et al ., ; Ishiyama et al ., ; Asano et al ., ; Ohata et al ., ; Iida et al ., ), as well as arterial carbon dioxide tension (Ganjoo et al ., ). For instance, the reductions in CBF and pial arterial diameter in hypocapnic rats were larger than those in normocapnic rats.…”

Section: Discussionmentioning

confidence: 97%

Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Fukuda

Vazquez

Zong

et al. 2012

Eur J of Neuroscience

115

130

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This paper describes the effects of dexmedetomidine (DEX) 5 the active ingredient of medetomidine which is the latest popular sedative for functional magnetic resonance imaging (fMRI) in rodents 5 on multiple unit activity, local field potential (LFP), cerebral blood flow (CBF), pial vessel diameter (indicative of cerebral blood volume; CBV), and blood-oxygenation-level-dependent (BOLD) fMRI. These measurements were obtained from the rat somatosensory cortex during 10-s forepaw stimulation. We found that the continuous intravascular systemic infusion of DEX (50μg/kg/h, doses typically used in fMRI studies) caused epileptic activities and that supplemental isoflurane administration of ~0.3% helped suppress the development of epileptic activities and maintained robust neuronal and hemodynamic responses up to 3 hours. Supplemental administration of nitrous oxide (N2O) in addition to DEX nearly abolished hemodynamic responses even if neuronal activity remained. Under DEX-ISO anesthesia, spike firing rate and the delta power of LFP increased, while beta and gamma power decreased compared to ISO-only anesthesia. DEX administration caused pial arteries and veins to constrict nearly equally, resulting in decreases in baseline CBF and CBV. Evoked LFP and CBF responses to forepaw stimulation were largest at a frequency of 8–10 Hz, and a non-linear relationship was observed. Similarly, BOLD fMRI responses measured at 9.4 Tesla were largest at a frequency of 10 Hz. Both pial arteries and veins dilated rapidly (artery, 32.2%; vein, 5.8%), while venous diameter changes returned to baseline slower than arteries. These results will be useful for designing, conducting and interpreting fMRI experiments under DEX sedation.

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Section: Discussionmentioning

confidence: 97%

Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Fukuda

Vazquez

Zong

et al. 2012

Eur J of Neuroscience

115

130

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“…ISO and DMED have inverse effects on the vasculature, with ISO causing vasodilation and DMED causing vasoconstriction (Ohata et al, 1999). The vascular smooth muscle under ISO may become relaxed and reduce the vessel’s ability to pulsate quickly; on the contrary, the vessel wall under DMED could become tighter, facilitating higher frequency pulsation.…”

Section: Discussionmentioning

confidence: 99%

Infraslow LFP correlates to resting-state fMRI BOLD signals

et al. 2013

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The slow fluctuations of the blood-oxygenation-level dependent (BOLD) signal in resting-state fMRI are widely utilized as a surrogate marker of ongoing neural activity. Spontaneous neural activity includes a broad range of frequencies, from infraslow (< 0.5 Hz) fluctuations to fast action potentials. Recent studies have demonstrated a correlative relationship between the BOLD fluctuations and power modulations of the local field potential (LFP), particularly in the gamma band. However, the relationship between the BOLD signal and the infraslow components of the LFP, which are directly comparable in frequency to the BOLD fluctuations, has not been directly investigated. Here we report a first examination of the temporal relation between the resting-state BOLD signal and infraslow LFPs using simultaneous fMRI and full-band LFP recording in rat. The spontaneous BOLD signal at the recording sites exhibited significant localized correlation with the infraslow LFP signals as well as with the slow power modulations of higher-frequency LFPs (1-100 Hz) at a delay comparable to the hemodynamic response time under anesthesia. Infraslow electrical activity has been postulated to play a role in attentional processes, and the findings reported here suggest that infraslow LFP coordination may share a mechanism with the large-scale BOLD-based networks previously implicated in task performance, providing new insight into the mechanisms contributing to the resting state fMRI signal.

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“…In the first possibility, the difference is due to dexmedetomidine and isoflurane affecting the vascular tone in very different manners (see Appendix A and (Ohata et al, 1999)). The observed increase in the periods of QPPs would thus suggest that QPPs may be propagating through vasomotion.…”

Section: Discussionmentioning

confidence: 99%

Quasi-periodic patterns (QPP): Large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity

et al. 2014

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Functional connectivity measurements from resting state blood-oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) are proving a powerful tool to probe both normal brain function and neuropsychiatric disorders. However, the neural mechanisms that coordinate these large networks are poorly understood, particularly in the context of the growing interest in network dynamics. Recent work in anesthetized rats has shown that the spontaneous BOLD fluctuations are tightly linked to infraslow local field potentials (LFPs) that are seldom recorded but comparable in frequency to the slow BOLD fluctuations. These findings support the hypothesis that long-range coordination involves low frequency neural oscillations and establishes infraslow LFPs as an excellent candidate for probing the neural underpinnings of the BOLD spatiotemporal patterns observed in both rats and humans. To further examine the link between large-scale network dynamics and infraslow LFPs, simultaneous fMRI and microelectrode recording were performed in anesthetized rats. Using an optimized filter to isolate shared components of the signals, we found that time-lagged correlation between infraslow LFPs and BOLD is comparable in spatial extent and timing to a quasi-periodic pattern (QPP) found from BOLD alone, suggesting that fMRI-measured QPPs and the infraslow LFPs share a common mechanism. As fMRI allows spatial resolution and whole brain coverage not available with electroencephalography, QPPs can be used to better understand the role of infraslow oscillations in normal brain function and neurological or psychiatric disorders.

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Intravenous Dexmedetomidine Inhibits Cerebrovascular Dilation Induced by Isoflurane and Sevoflurane in Dogs

Cited by 37 publications

References 25 publications

Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Infraslow LFP correlates to resting-state fMRI BOLD signals

Quasi-periodic patterns (QPP): Large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity

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Intravenous Dexmedetomidine Inhibits Cerebrovascular Dilation Induced by Isoflurane and Sevoflurane in Dogs

Cited by 37 publications

References 25 publications

Effects of the α2‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Effects of the α2‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Infraslow LFP correlates to resting-state fMRI BOLD signals

Quasi-periodic patterns (QPP): Large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity

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Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex

Effects of the α₂‐adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex