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Locomotor, respiratory and cardiac rhythms during locomotion in decerebrate cats
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LOCOMOTOR, R E S P I R A T O R Y AND CARDIAC R H Y T H M S DURING L O C O M O T I O N IN D E C E R E B R A T E CATS. KOICHI KAWAHARA, K Y U I C H I NIIZEKI*~ A N D M A S A Y U K I SUZUKI*, D e p a r t m e n t of E l e c t r i c a l and I n f o r m a t i o n Engineering, F a c u l t y of E n s i n e e r i n $, Y a m a s a t a University, Y o n e z a w a 992, Japan. During exercise, respiratory and cardiac rhythms are considered to be synchronized with the exercise rhythm in man.
However, the strength of coupling between those rhythms seems to be weak.
We have performed correlation analysis on the coupling between locomotor, respiratory and cardiac rhythms in unanesthetized, decerebrate cats. The animals were deeerehrated under halothane anesthesia. To induce locomotion on a treadmill belt, tonic electrical stimulation was delivered to the mesencephalic locomotor region.
Correlation analysis showed that the strength of locomotor-respiratory
coupling was weak during a slow walk and slow running, but became markedly greater during a running. In contrast, no evidence of synchronization between cardiac and locomotor rhythms was found during locomotion.
Based on these results, we proposed a hypostatized model describing the functional
hierarchical organization of biological oscillators.
CIRCADIAN RHYTHMS OF PINEAL EXTRACELLULAR INDOLES IN FREELY MOVING RATS. TAKAHARU AZEKAWA*, ATSUKO SANO*, KAZ~IHIRO AOI'. HIROYOSHI SEI* AND YUSUKE MOR1TA, Deoartment of Phvsioloav. School of ~edicine. The University of Tokushima. 3 Kuramoto Tokushima 770. Jaoan. We measured basal levels of extracellular indoleamines in pineal microdialysates taken from freely moving rats and observed their circadian rhythms over 24 hours. Male Wistar rats, weighing 250-350g, were housed in individual cages under a 12-hr lighting condition (lights on at 0700, about 2501x). The guide cannula for microdialysis probe was implanted under anesthesia with pentobarbital sodium (Nembutal, 50mg/kg i.p.). In vivo measurement was carried out after about two weeks of postoperative recovery. Pineal indoleamines in microdialysates analyzed by high-performance liquid chromatography with electrochemical detection. The present study yielded several findings as follows: (i)The content of serotonin (5-H1-) was highest among extracellular indole derivatives in the pineaI gland, being rather higher than its reported levels in the cortex and hippocampus. (ii) The content of pineal extracellular 5-HT exhibited a circadian rhythm, being higher during the light period and lower during the dark period. There was a temporary increase in the 5-HT content over the transition from the light period to the dark period. (iii) The contents of both 5-hydroxytryptophol and 5-hydroxyindoleacetic acid had parallel circadian rhythms with that of 5-HT. (iv) The content of N-acetylserotonin showed a remarkable circadian rhythm, remaining low during the light period and rising about 2-hr later at the beginning of the dark period.
37. Somatosensory SHAPE AND SYMMETRICAL P R O P E R T I E S OF THE R E C E P T I V E FIELD OF MECHANOSENSORY NEURONS. SHIKO CHICHIBU AND ATSUSHI CHIBA. D e p a r t m e n t of Physiology, Kinki U n i v e r s i t y School o f Medicine 7 0 s a k a - S a y a m a , Osaka 589, Jap-an. We examined the shape and s y m m e t r i c a l properties of the three ma~or types of mechanosensory hairs on the endopodium of the crayfish (Procambarus clarkii) first antenna. Each hair was innervated by a pair of sensory neurons. The response c h a r a c t e r i s t i c s to code the a t t r i b u t e of mechanical stimuli between paired neurons were different. The A-unit, which coded the transient c h a r a c t e r i s t i c s of the stimuli, had a n a r r o w elongated receptive field, while the V- and D- units showed limited receptive fields. The receptive field of the A-unit was nearly symmetrical on either side of the preferred main axis. The receptive fields of the V- and D units were asymmetrical in the a n t i - p r e f e r r e d d i r e c t i o n with strong i n d e n t a t i o n on the main axis. These properties may contribute to orient the d i r e c t i o n of the stimulus from d i f f e r e n t i a l input sources. The shape of the receptive field c o r r e s p o n d e d to the function to detect d i r e c t i o n of the stimuli. Movability of the hair base also indicated the importance of o r i e n t i n g function of the stimuli.
LOCOMOTOR, R E S P I R A T O R Y AND CARDIAC R H Y T H M S DURING L O C O M O T I O N IN D E C E R E B R A T E CATS. KOICHI KAWAHARA, K Y U I C H I NIIZEKI*~ A N D M A S A Y U K I SUZUKI*, D e p a r t m e n t of E l e c t r i c a l and I n f o r m a t i o n Engineering, F a c u l t y of E n s i n e e r i n $, Y a m a s a t a University, Y o n e z a w a 992, Japan. During exercise, respiratory and cardiac rhythms are considered to be synchronized with the exercise rhythm in man.
However, the strength of coupling between those rhythms seems to be weak.
We have performed correlation analysis on the coupling between locomotor, respiratory and cardiac rhythms in unanesthetized, decerebrate cats. The animals were deeerehrated under halothane anesthesia. To induce locomotion on a treadmill belt, tonic electrical stimulation was delivered to the mesencephalic locomotor region.
Correlation analysis showed that the strength of locomotor-respiratory
coupling was weak during a slow walk and slow running, but became markedly greater during a running. In contrast, no evidence of synchronization between cardiac and locomotor rhythms was found during locomotion.
Based on these results, we proposed a hypostatized model describing the functional
hierarchical organization of biological oscillators.
CIRCADIAN RHYTHMS OF PINEAL EXTRACELLULAR INDOLES IN FREELY MOVING RATS. TAKAHARU AZEKAWA*, ATSUKO SANO*, KAZ~IHIRO AOI'. HIROYOSHI SEI* AND YUSUKE MOR1TA, Deoartment of Phvsioloav. School of ~edicine. The University of Tokushima. 3 Kuramoto Tokushima 770. Jaoan. We measured basal levels of extracellular indoleamines in pineal microdialysates taken from freely moving rats and observed their circadian rhythms over 24 hours. Male Wistar rats, weighing 250-350g, were housed in individual cages under a 12-hr lighting condition (lights on at 0700, about 2501x). The guide cannula for microdialysis probe was implanted under anesthesia with pentobarbital sodium (Nembutal, 50mg/kg i.p.). In vivo measurement was carried out after about two weeks of postoperative recovery. Pineal indoleamines in microdialysates analyzed by high-performance liquid chromatography with electrochemical detection. The present study yielded several findings as follows: (i)The content of serotonin (5-H1-) was highest among extracellular indole derivatives in the pineaI gland, being rather higher than its reported levels in the cortex and hippocampus. (ii) The content of pineal extracellular 5-HT exhibited a circadian rhythm, being higher during the light period and lower during the dark period. There was a temporary increase in the 5-HT content over the transition from the light period to the dark period. (iii) The contents of both 5-hydroxytryptophol and 5-hydroxyindoleacetic acid had parallel circadian rhythms with that of 5-HT. (iv) The content of N-acetylserotonin showed a remarkable circadian rhythm, remaining low during the light period and rising about 2-hr later at the beginning of the dark period.
37. Somatosensory SHAPE AND SYMMETRICAL P R O P E R T I E S OF THE R E C E P T I V E FIELD OF MECHANOSENSORY NEURONS. SHIKO CHICHIBU AND ATSUSHI CHIBA. D e p a r t m e n t of Physiology, Kinki U n i v e r s i t y School o f Medicine 7 0 s a k a - S a y a m a , Osaka 589, Jap-an. We examined the shape and s y m m e t r i c a l properties of the three ma~or types of mechanosensory hairs on the endopodium of the crayfish (Procambarus clarkii) first antenna. Each hair was innervated by a pair of sensory neurons. The response c h a r a c t e r i s t i c s to code the a t t r i b u t e of mechanical stimuli between paired neurons were different. The A-unit, which coded the transient c h a r a c t e r i s t i c s of the stimuli, had a n a r r o w elongated receptive field, while the V- and D- units showed limited receptive fields. The receptive field of the A-unit was nearly symmetrical on either side of the preferred main axis. The receptive fields of the V- and D units were asymmetrical in the a n t i - p r e f e r r e d d i r e c t i o n with strong i n d e n t a t i o n on the main axis. These properties may contribute to orient the d i r e c t i o n of the stimulus from d i f f e r e n t i a l input sources. The shape of the receptive field c o r r e s p o n d e d to the function to detect d i r e c t i o n of the stimuli. Movability of the hair base also indicated the importance of o r i e n t i n g function of the stimuli.