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Volatile anesthetics and opisthotonus in mice
S162
35. Reticular formation THE F A C I O - F A C I A L REFLEX IN CAT, WITH SPECIAL REFERENCE TO THE LATERAL BULBAR R E T I C U L A R F O R M A T I O N (LBRF). T S U T O M U TANAKA, T O S H I H I R O ASAHARA*, AND #YOSHIKI TAKEUCHI, Department of Physioo--~-g~, S c h - - ~ o f Medicine,--M~iver--~ty, Tsu, Mie, 514, #Department o f An-atomy, School o--f--~ic-fne, Nagoya nU'n-lversity, 65 Ts--d-fuma-~cho, Showa-ku, Nagoya 466, Japan. M o r p h o l o g i c a l and e l e c t r o p h y s i o l o g i c a l techniques were employed to analyze the facio-facial reflex p a t h w a y in Nembutal a n e s t h e t i z e d cats. After injection of wheat germ agglutinin conjugated h o r s e r a d i s h peroxidase to the cut end of the facial nerve branches, a heavily labeled bundle of the vagal nerve was observed to enter the brain stem and gather along the dorsolateral border of the spinal trigeminal tract. Distinct terminal areas of the labeled fibers were present in the LBRF dorsomedial to the spinal trigeminal tract. Stimulation of the LBRF evoked p o l y s y n a p t i c EPSPs with latencies of 1.6-3.4 msec (mean 2.5t0.6 msec, n = 3 3 ) No h y p e r p o l a r i z i n g p o t e n t i a l s could be evoked in the facial neurons after LBRF stimulation. Transection of the facial primary afferents in the LBRF just rostral to the obex abolished the synaptically activated potentials due to facial afferent volleys. Stimulation of the c o n t r a l a t e r a l LBRF also elicited e x c l u s i v e l y polysynaptic EPSPs with latencies of 1.8-3.4 msec (2.6+0.6 msec, n=9). We conclude that the central terminal areas of facial afferents are p r i m a r i l y within the LBRF, and that the LBRF projects a f a c i l i t a t o r y effect to the facial m o t o n e u r o n s on both sides.
VOLATILE
ANESTHETICS
AND O P I S T H O T O N U S
IN MICE
H I S A O KOMATSU~ SATOSHI YOKONO~ ~ KENJI OGLI~ ~ AND T E T U H I D E H MURAKAMI 2 Departments of A n e s t h e s i o l o g y & E m e r q e n c y M e d i c i n e ~ a ~ d Bioloqy =, Kagawa Medical School, 1750-I Ikenobe, Miki-cho, Kita-qun, K a q a w a 761-07,
Japan
Enflurane, a haloether anesthetic, has CNS stimulating action, but its structural isomer isoflurane is believed not to have. However, we found that isoflurane, rather than enflurane, produced a high incidence of o p i s t h o t o n u s in some strains of mice. We investigated the incidence of o p i s t h o t o n u s in three age groups (10+2 weeks, 6+I months, 12+I months) of mice by four haloether anesthetics (sevoflurane, isoflurane, enflurane, and methoxyflurane) and a haloalkane (halothane). Average incidences in the three age groups were 84% for sevoflurane, 79% for isoflurane, 48% for enflurane, 16% for m e t h o x y f l u r a n e , and I% for halothane. This order agrees with the rapidity of anesthetic i n d u c t i o n and recovery except for halothane, which may relate to the structural difference between haloether and haloalkane. There was no age related difference in s u s c e p t i b i l i t y to a n e s t h e t i c - i n d u c e d o p i s t h o t o n u s except for enflurane, in which the incidence of o p i s t h o t o n u s increased with age.
35. Reticular formation THE F A C I O - F A C I A L REFLEX IN CAT, WITH SPECIAL REFERENCE TO THE LATERAL BULBAR R E T I C U L A R F O R M A T I O N (LBRF). T S U T O M U TANAKA, T O S H I H I R O ASAHARA*, AND #YOSHIKI TAKEUCHI, Department of Physioo--~-g~, S c h - - ~ o f Medicine,--M~iver--~ty, Tsu, Mie, 514, #Department o f An-atomy, School o--f--~ic-fne, Nagoya nU'n-lversity, 65 Ts--d-fuma-~cho, Showa-ku, Nagoya 466, Japan. M o r p h o l o g i c a l and e l e c t r o p h y s i o l o g i c a l techniques were employed to analyze the facio-facial reflex p a t h w a y in Nembutal a n e s t h e t i z e d cats. After injection of wheat germ agglutinin conjugated h o r s e r a d i s h peroxidase to the cut end of the facial nerve branches, a heavily labeled bundle of the vagal nerve was observed to enter the brain stem and gather along the dorsolateral border of the spinal trigeminal tract. Distinct terminal areas of the labeled fibers were present in the LBRF dorsomedial to the spinal trigeminal tract. Stimulation of the LBRF evoked p o l y s y n a p t i c EPSPs with latencies of 1.6-3.4 msec (mean 2.5t0.6 msec, n = 3 3 ) No h y p e r p o l a r i z i n g p o t e n t i a l s could be evoked in the facial neurons after LBRF stimulation. Transection of the facial primary afferents in the LBRF just rostral to the obex abolished the synaptically activated potentials due to facial afferent volleys. Stimulation of the c o n t r a l a t e r a l LBRF also elicited e x c l u s i v e l y polysynaptic EPSPs with latencies of 1.8-3.4 msec (2.6+0.6 msec, n=9). We conclude that the central terminal areas of facial afferents are p r i m a r i l y within the LBRF, and that the LBRF projects a f a c i l i t a t o r y effect to the facial m o t o n e u r o n s on both sides.
VOLATILE
ANESTHETICS
AND O P I S T H O T O N U S
IN MICE
H I S A O KOMATSU~ SATOSHI YOKONO~ ~ KENJI OGLI~ ~ AND T E T U H I D E H MURAKAMI 2 Departments of A n e s t h e s i o l o g y & E m e r q e n c y M e d i c i n e ~ a ~ d Bioloqy =, Kagawa Medical School, 1750-I Ikenobe, Miki-cho, Kita-qun, K a q a w a 761-07,
Japan
Enflurane, a haloether anesthetic, has CNS stimulating action, but its structural isomer isoflurane is believed not to have. However, we found that isoflurane, rather than enflurane, produced a high incidence of o p i s t h o t o n u s in some strains of mice. We investigated the incidence of o p i s t h o t o n u s in three age groups (10+2 weeks, 6+I months, 12+I months) of mice by four haloether anesthetics (sevoflurane, isoflurane, enflurane, and methoxyflurane) and a haloalkane (halothane). Average incidences in the three age groups were 84% for sevoflurane, 79% for isoflurane, 48% for enflurane, 16% for m e t h o x y f l u r a n e , and I% for halothane. This order agrees with the rapidity of anesthetic i n d u c t i o n and recovery except for halothane, which may relate to the structural difference between haloether and haloalkane. There was no age related difference in s u s c e p t i b i l i t y to a n e s t h e t i c - i n d u c e d o p i s t h o t o n u s except for enflurane, in which the incidence of o p i s t h o t o n u s increased with age.