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Author Notes:

Xiaodong Zhang, Email: xzhang8@emory.edu

The authors are grateful to Sudeep Patel and Ruth Connelly for assistance in data acquisition and animal handling, and the Center for Magnetic Resonance Research (CMRR) of University of Minnesota for sharing the multiband EPI pulse sequence with us.

The authors have no conflict of interest to disclose.


Research Funding:

The project is supported by the Office of Research Infrastructure Programs (OD P51OD011132).


  • Anesthetics, Inhalation
  • Animals
  • Brain
  • Cerebrovascular Circulation
  • Heart Rate
  • Isoflurane
  • Ketamine
  • Macaca mulatta
  • Male
  • Pregnanediones

Effects of alfaxalone on cerebral blood flow and intrinsic neural activity of rhesus monkeys: A comparison study with ketamine


Journal Title:

Magnetic Resonance Imaging


Volume 75


, Pages 134-140

Type of Work:

Article | Post-print: After Peer Review


Objective: Alfaxalone has been used increasingly in biomedical research and veterinary medicine of large animals in recent years. However, its effects on the cerebral blood flow (CBF) physiology and intrinsic neuronal activity of anesthetized brains remain poorly understood. Methods: Four healthy adult rhesus monkeys were anesthetized initially with alfaxalone (0.125 mg/kg/min) or ketamine (1.6 mg/kg/min) for 50 min, then administrated with 0.8% isoflurane for 60 min. Heart rates, breathing beats, and blood pressures were continuously monitored. CBF data were collected using pseudo-continuous arterial spin-labeling (pCASL) MRI technique and rsfMRI data were collected using single-shot EPI sequence for each anesthetic. Results: Both the heart rates and mean arterial pressure (MAP) remained more stable during alfaxalone infusion than those during ketamine administration. Alfaxalone reduced CBF substantially compared to ketamine anesthesia (grey matter, 65 ± 22 vs. 179 ± 38 ml/100g/min, p<0.001; white matter, 14 ± 7 vs. 26 ± 6 ml/100g/min, p < 0.05); In addition, CBF increase was seen in all selected cortical and subcortical regions of alfaxalone-pretreated monkey brains during isoflurane exposure, very different from the findings in isoflurane-exposed monkeys pretreated with ketamine. Also, alfaxalone showed suppression effects on functional connectivity of the monkey brain similar to ketamine. Conclusion: Alfaxalone showed strong suppression effects on CBF of the monkey brain.The residual effect of alfaxalone on CBF of isoflurane-exposed brains was evident and monotonous in all the examined brain regions when used as induction agent for inhalational anesthesia. In particular, alfaxalone showed similar suppression effect on intrinsic neuronal activity of the brain in comparison with ketamine. These findings suggest alfaxalone can be a good alternative to veterinary anesthesia in neuroimaging examination of large animal models. However, its effects on CBF and functional connectivity should be considered.

Copyright information:

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