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Differential glucose needs of myelinated and unmyelinated axons in vitro
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$205
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D I F F E R E N T I A L GLUCOSE NEEDS OF M Y E L I N A T E D , A N D U N M Y E L I N A T E D I 2 4 9 Po AXONS IN VITRO. B.R. Fink and A. Cairns . Department of I Thursday I Anesthesiology, Univ. of Washington, Seattle, WA 98195 USA Aim: Since many local anesthetic: solutions lack glucose we investigated the effect of glucose lack on impulse conduction in peripheral nerve. Methods: Sheathed and desheathed cervical vagus nerve of rabbit was incubated at 37.5°C in buffered R i n g e r - g l u c o s e solution. Fast (A) and slow (C) components of the compound action potential elicited by a supramaximal stimulus were recorded every 5 - i0 min to determine the rate of decline ol the amplitude of the potentials in various concentrations of glucose. Results: In glucose 0, 0.5, i, 2, 5, I0 mM, t h e A potentials in sheathed nerves decreased at most 94, 88, 70, 56, 42, 14 percent in any one hour~ the C potentials decreased 96, i00, 44, 8, 8, 12 percent. Thus in sheathed nerves m i n i m u m amplitude decline required i0 ngl glucose for A fibers, 2 ~I for C fibers. In desheathed nerves the glucose requirement for m i n i m u m decline of A fibers was 5 raM, for C fibers 0.5 raM. The A fibers always extinguished first. Discussion: The higher glucose requirement in sheathed nerves is explained by a perineurial barrier to the inward diffusion of glucose. Assuming inexcitability occurred whe~l a critical amount of potassium has leaked out of the axons, on the basis of size one would expect the small, slow fibers to be e x t i n g u i s h e d first. In fact, they were extinguished last. P r e s u m a b l y they needed less glucose to m a i n t a i n the Na + - K ÷ 'pump'. Conclusion: Small, unmyelinated fibers need less glucose to maintain the Na+ - K+ pump than large, myelinated fibers. This suggests there may be a ]ower m e t a b o l i c rate in unmyelinated fibers than at nodes of Ranvier. This factor may contribute to the selective p r e s e r v a t i o n of small fibers Ln nerve compression and certain peripheral pain syndromes. ((;rant tim 27678-0] National Institutes of Health)
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SPINAL G A N G L I O N CELLS INNERVATING THE PANCREAS OF THE CAT AS I D E M O N S T R A T E D BY RETROGRADE A X O N A L TRANSPORT OF H O R S E R A D I S H I 2 5 0 Po PEROXIDASE(HRP). OK. hnishi, A. Ogasawara, N. Ohgushi, 1 Thursday N. Kan, and K. Tsunekawa, Department of Surgery, University of Ehime, Matsuyama, 790, JAPAN Purpose: To determine the characteristics of visceral pain on the pancreatic disease, spinal ganglion cells innervating the pancreas of the cat were demonstrated using the axonal transport of HRP. Methods: Six adult cats were a n e s t h e t i z e d with nembutal. A total of 300mg of a 33% saline solution of HRP(Sigma Type If) was injected into the pancreas parenehyma. This experimental procedures were performed according to G r a h a m & Karnovsky as described previously. 4 cases were injected into b i l a t e r a l lobes. On one of them performed bilateral celiac ganglionectomy and on the other one done left celiac ganglionectomy. 2 animals were kept intact. 2 cases were injected into lateral lobes. On the one hand left lobe, on the other hand right lobe. Results and Conclusion: After injection into the both lobes of the pancreas, H R P - ] a b e l l e d cells were observed b i l a t e r a l l y w i t h i n spinal gnaglia T2-L4. They were most numerous in ganglia T4-LI. Injected into the lateral lobe, labelled neurons were d e m o n s t r a t e d same to the d i s t r i b u t i o n of both lobes, and were no different significantly b e t w e e n the left lobe and the right lobe. After bilateral celiac ganglionectomy, labelled cells were decreased remarkably, showed such cells bilateraly, w i t h i n all levels. After left celiac gnaglioneetomy, ~eft labelled neurons were only a few. The site of visceral pain was unclear and overlaped. And, the almost afferent nerves of the pancreas passed through the celiac gnaglion to spinal ganglion. And, at the more central nerves of the celiac ganglion levels, they passed through right celiac ganglion to right spinal ganglion or left to left.
$205
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D I F F E R E N T I A L GLUCOSE NEEDS OF M Y E L I N A T E D , A N D U N M Y E L I N A T E D I 2 4 9 Po AXONS IN VITRO. B.R. Fink and A. Cairns . Department of I Thursday I Anesthesiology, Univ. of Washington, Seattle, WA 98195 USA Aim: Since many local anesthetic: solutions lack glucose we investigated the effect of glucose lack on impulse conduction in peripheral nerve. Methods: Sheathed and desheathed cervical vagus nerve of rabbit was incubated at 37.5°C in buffered R i n g e r - g l u c o s e solution. Fast (A) and slow (C) components of the compound action potential elicited by a supramaximal stimulus were recorded every 5 - i0 min to determine the rate of decline ol the amplitude of the potentials in various concentrations of glucose. Results: In glucose 0, 0.5, i, 2, 5, I0 mM, t h e A potentials in sheathed nerves decreased at most 94, 88, 70, 56, 42, 14 percent in any one hour~ the C potentials decreased 96, i00, 44, 8, 8, 12 percent. Thus in sheathed nerves m i n i m u m amplitude decline required i0 ngl glucose for A fibers, 2 ~I for C fibers. In desheathed nerves the glucose requirement for m i n i m u m decline of A fibers was 5 raM, for C fibers 0.5 raM. The A fibers always extinguished first. Discussion: The higher glucose requirement in sheathed nerves is explained by a perineurial barrier to the inward diffusion of glucose. Assuming inexcitability occurred whe~l a critical amount of potassium has leaked out of the axons, on the basis of size one would expect the small, slow fibers to be e x t i n g u i s h e d first. In fact, they were extinguished last. P r e s u m a b l y they needed less glucose to m a i n t a i n the Na + - K ÷ 'pump'. Conclusion: Small, unmyelinated fibers need less glucose to maintain the Na+ - K+ pump than large, myelinated fibers. This suggests there may be a ]ower m e t a b o l i c rate in unmyelinated fibers than at nodes of Ranvier. This factor may contribute to the selective p r e s e r v a t i o n of small fibers Ln nerve compression and certain peripheral pain syndromes. ((;rant tim 27678-0] National Institutes of Health)
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SPINAL G A N G L I O N CELLS INNERVATING THE PANCREAS OF THE CAT AS I D E M O N S T R A T E D BY RETROGRADE A X O N A L TRANSPORT OF H O R S E R A D I S H I 2 5 0 Po PEROXIDASE(HRP). OK. hnishi, A. Ogasawara, N. Ohgushi, 1 Thursday N. Kan, and K. Tsunekawa, Department of Surgery, University of Ehime, Matsuyama, 790, JAPAN Purpose: To determine the characteristics of visceral pain on the pancreatic disease, spinal ganglion cells innervating the pancreas of the cat were demonstrated using the axonal transport of HRP. Methods: Six adult cats were a n e s t h e t i z e d with nembutal. A total of 300mg of a 33% saline solution of HRP(Sigma Type If) was injected into the pancreas parenehyma. This experimental procedures were performed according to G r a h a m & Karnovsky as described previously. 4 cases were injected into b i l a t e r a l lobes. On one of them performed bilateral celiac ganglionectomy and on the other one done left celiac ganglionectomy. 2 animals were kept intact. 2 cases were injected into lateral lobes. On the one hand left lobe, on the other hand right lobe. Results and Conclusion: After injection into the both lobes of the pancreas, H R P - ] a b e l l e d cells were observed b i l a t e r a l l y w i t h i n spinal gnaglia T2-L4. They were most numerous in ganglia T4-LI. Injected into the lateral lobe, labelled neurons were d e m o n s t r a t e d same to the d i s t r i b u t i o n of both lobes, and were no different significantly b e t w e e n the left lobe and the right lobe. After bilateral celiac ganglionectomy, labelled cells were decreased remarkably, showed such cells bilateraly, w i t h i n all levels. After left celiac gnaglioneetomy, ~eft labelled neurons were only a few. The site of visceral pain was unclear and overlaped. And, the almost afferent nerves of the pancreas passed through the celiac gnaglion to spinal ganglion. And, at the more central nerves of the celiac ganglion levels, they passed through right celiac ganglion to right spinal ganglion or left to left.