1995 Fiscal Year Final Research Report Summary
Pharmacology, physiology and clinical application of pregnancy-induced analgesia
| Project/Area Number |
06671544
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | SAPPORO MEDICAL UNIVERSITY |
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Principal Investigator |
IWASAKI Hiroshi SAPPORO MEDICAL UNIVERSITY,SCHOOL OF MEDICINE DEPARTMENT OF ANESTHESIOLOGY,ASSOCIATE PROFESSOR, 医学部, 助教授 (70223386)
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| Project Period (FY) |
1994 – 1995
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| Keywords | pregnancy / endogenous analgesia / calcium channel blocker |
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| Research Abstract |
This is one of serires of studies to examine the physiology of pregnacy-induced analgesia in rats. The main purpose of this study was to examine the effects of 1-type calcium channel blockers on pregnancy-induced analgesia.
(1) This study was designed to investigate the effects of the intrathecal calcium channel blocker, verapamil, on the spinal anesthesia from lidacaine and tetracaine. Male Sprague-Dawley rats were chronically implanted with lumbar intrathecal catheters. Tail flick (TF) and mechanical paw pressure (MPP) tests were used to assess thermal and mechanical nociceptive threshold, respectively. Motor function was assessed using a modified Langerman's scale. Intrathecal lidocaine of tetracaine alone showed the prolongation of TF latency, the increase of MPP threshold, and the increase in motor function scale in a time-and dose-dependent manner. Although intrathecal verapamil alone demonstrated neither sensory nor motor block), the combination of lidocaine or tetracaine and ver
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apamil produced the more potent and prolonged antinociception and motor block when compared with local anesthetics alone. (2) We have studied the effects of three different types of calcium channel blockers (verapamil, diltiazem, and nicardipine) on local lidocaine sensory block. Standard tail flick (TF) test was employed to quantify the duration and dgree of local lidocaine-induced conduction block in rats. After obtaining baseline TF test, two 100mug of 0.3% lidocaine alone, a combination of verapamil, diltiazem, or nicardipine. and a large dose of calcium channel blockers were injected on opposite sites of the tail base. Coadministration of lidocaine and three doses of 1-type calcum channel blockers significant increases of antinociception at the level of the peripheral nerve. (3) The study was designed to examine the intrathecally administered calcium channel blocker, verapamil, on pregnancy-induced analgesia inrats. To assess thermal nociceptive threshold, tail flick test was emolyed. In pregnant rats, a significant increase in TF was demonstrated on late pregnancy. Intrathecally administered verapamil produced a significant prolongation of TF late in pregnancy. Less
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