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1.Research Summary

The Department of Anesthesiology covers a wide range of research subjects. Particularly, we have a long history of electrophysiological studies on pain, cerebrospinal ischemia, and anesthesia mechanisms mainly by the patch-clamp and intracellular recording techniques. The results obtained have been highly valued in Japan and foreign countries. We also conduct clinical research on perioperative management using transesophageal echocardiography and spinal cord monitoring. Numerous studies on ultrasound-guided peripheral nerve blocks, which have become markedly widespread in recent years, are conducted.

2.Research Groups

3-1.Basic Research Group

Research subjects

Research on mechanisms of actions of local anesthetics in the spinal cord

Local anesthetics inhibit nerve conduction, thereby exerting their actions. Their actions are displayed by blocking sodium channels in nerve fibers. In recent years, however, the actions of local anesthetics have been assumed to be more complex. The identification of new action mechanisms can increase the possibility of local anesthetics being used as analgesics. We are performing electrophysiological analyses on spinal dorsal horn neurons to examine the actions of local anesthetics in the spinal cord.

Research on neuronal protection against spinal cord ischemia

We investigate the actions of various anesthetics for spinal cord ischemia. Paraplegia secondary to spinal cord ischemia is a complication caused by cardiac or macrovascular surgery. In perioperative management, anesthesiologists induce a generalized anesthetic state by using sedatives and analgesics. We examine their actions to determine how these drugs influence the clinical condition of spinal cord ischemia on the cellular level by applying electrophysiological procedures.

Research on the mechanism of anesthesia using molecular, behavioral and pharmacological approaches

Neurotransmitter receptors possessed by neurons are assumed to be important targets of anesthetics and analgesics. Behavioral analyses of mice to which modulating drugs for specific receptors are administered or mice with specific receptor defects have enabled us to search for a direct relationship between the specific receptors and behaviors such as anesthesia and chronic pain. Therefore, we are conducting research on the action mechanisms of anesthetics and the onset mechanisms of chronic pain using pharmacological and biomolecular approaches. This research leads to the development of drugs with good efficacy and few adverse reactions.

Study on therapeutic targets of neuropathic pain

Neuropathic pain is an intractable disease, and it is very important to identify its onset mechanism for establishing therapeutic strategies. We were the first in the world to report the effect of Sema3A, an axonal guidance factor, to attenuate neuropathic pain. Currently, we are implementing research to reveal the relationship between intracellular signaling of Sema3A and the mechanism of pain relief from the biochemical and histological viewpoints.

3-2.Clinical Research Group

Research subjects

Research on endoleak detection by transesophageal echocardiographic-guidance for thoracic stent-graft implantation

During stent-graft implantation for thoracic aortic aneurysm, when blood flow in the aortic aneurysm stops, and thrombus formation progresses, smoke-like echo in the aneurysm disappears, and echo brightness increases. We have proven the hypothesis that when intraoperative transesophageal echocardiography shows a remaining smoke-like echo in the aneurysm and poor thrombus formation (increased brightness), endoleak remains, often resulting in aneurysm enlargement.

Clinical research on ultrasound-guided peripheral nerve blocks

In recent years, ultrasound-guided peripheral nerve blocks have become popular. We are conducting clinical research on the usefulness and safety of peripheral nerve blocks of various sites.

Research on spinal cord monitoring

Cerebrospinal monitoring by evoked potential measurement is useful for identifying impairments of nerve conduction pathways and central nervous system ischemia using surgical procedures such as vertebral/spinal surgery and aortic surgery involving spinal cord feeding arteries. Evoked potential changes according to not only surgical procedures but also various other factors. Particularly, the influence of anesthetics is important; thus, we are carrying out research to be able to stably record evoked potentials for an accurate diagnosis. Furthermore, we are performing research on the effects of drugs other than anesthetics used during the perioperative period for neuronal protection.

4.Research Results

[Area] Anesthesiology

[Research subject]

Research on mechanisms of action of anesthetics and analgesics in the spinal cord

Elements such as sedation, analgesia and immobilization are necessary for general anesthesia. Among these, we focused on sedative and analgesic actions and conducted research on the action mechanisms of anesthetics and analgesics in the spinal cord using the patch-clamp technique.
DAMGO (-opioid receptor agonist) suppressed the amplitude of Aδ- and C-fiber-evoked excitatory postsynaptic currents. The degree of suppression was significantly greater for C-fibers than for Aδ-fibers. Opioids such as morphine administered into the spinal subarachnoid space were shown to more markedly suppress dull pain via C-fibers than rapid and sharp pain via Aδ-fibers.