Studies of local anesthetic action

Research Project

Project/Area Number	16591550
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Anesthesiology/Resuscitation studies
Research Institution	University OF Miyazaki
Principal Investigator	TAKASAKI Mayumi University of Miyazaki, Faculty of Medicine, Department of Anesthesiology and Intensive Care, Professor, 医学部, 教授 (30094212)
Co-Investigator(Kenkyū-buntansha)	SHIRASAKA Tetsuro University of Miyazaki, Faculty of Medicine, Department of Anesthesiology and Intensive Care, Assistant Professor, 医学部, 講師 (00274788) TANAKA Nobuhiko University of Miyazaki, Faculty of Medicine, Department of Anesthesiology and Intensive Care, Instructor, 医学部, 助手 (30264394)
Project Period (FY)	2004 – 2005
Project Status	Completed (Fiscal Year 2005)
Budget Amount *help	¥3,500,000 (Direct Cost: ¥3,500,000) Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000) Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
Keywords	Local anesthetics / Differential nerve block / Levobupivacaine / Ropivacaine
Research Abstract	Differential nerve block was studied with intact motor Aα and sensory Aα β fibers of the rat sciatic nerve. Ventral root fibers with conduction velocities faster than 32 m/sec and dorsal root fibers faster than 20 m/sec were classified as A α and A α β fibers, respectively. Compound action potentials (CAPs) were measured from A α and A α β fibers by electrical stimuli placed on the distal sciatic nerve. Levobupivacaine or ropivacaine is administered at a concentration of 0.0625%, 0.125%, or 0.25% in the pool containing the sciatic nerve. CAPs were decreased dose-dependently by the administration of levobupivacaine or ropivacaine. With the administration of 0.0625% levobupivacaine, CAPs of A α and A α β fibers were decreased by 36±13 (SD) % and 9±9%, respectively. These change was significantly greater in A α fibers than in A α β fibers. There was no significant difference in the decrease in CAPs of A α and A α β fibers at another concentrations of levobupivacaine and ropivacaine. Our results demonstrate that motor A α fibers are blocked greater than sensory A α β fibers with the direct administration of 0.0625% levobupivacaine.