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1652 Optical imaging of respiratory burst activity in medullary block preparation from newborn rats
S187 1651
UNILATERAL SENSORIMOTOR RAT. KOICHI Janan.
CEREBELLAL AND SOMATOSENSORY INPUTS TO THE CORTEX OF NEONATALLY CEREBRAL HEMISPHERECTOMIZED FUJIMURA. Dem. of Phvsiol.. Nagasaki Univ. Sch. of Med.. Nagasaki. 852,
It is known that unilateral motor cortex ablation in infancy results in the formation of a rich uncrossed corticospinal projection. The question remains, however, as to the organization of the input to the newly formed corticospinal projection system. In this study, the left fronto-parietal cortex of neonatal rat was aspirated, and after weaning, the rat was trained for getting food pellets by their right forelimb. Two to four months later, evoked potential to electrical stimulation of the cerebellar nuclei and distal forelimb muscles were recorded from the right sensorimotor cortex. The responses were evoked only by stimulation contralateral to the neocortex, although the rat could grasp a small food pellet in its ipsilateral forepaw.
1652
OPI’ICAL IMAGING OF RESPIRATORY BURST ACTIVITY IN MEDULLARY BLOCK PREPARATION FROM NEWBORN RATS. HIROSHI ONIMARU, ARATA KANAMARU AND IKUO HOMMA, Department of Physiologv, Showa University School of Medicine, Hatanodai l-5-8, Shinagawa-ku, Tokyo 142, Japan.
We report here on optical imaging of excitation propagation induced by electrical stimulation of the nucleus tractus solitarius (NTS) area and subsequent inspiratory burst activity in the ventrolateral medulla (VLM) of a medullary block preparation. A medullary block preparation with a thickness of 1.0-1.4 mm, including essential region for respiratory rhythm generation, was isolated from 0- to 4-day-old rats and stained with a fluorescent voltage-sensitive dye, RH795. Neuronal responses in the VLM evoked by electrical stimulation were recorded as a fluorescence change using an optical recording apparatus with a 128 x 128 photodiode array and a maximum time resolution of 0.6 ms (HR Deltaron 1700, Fuji Photo Film Co.). Motoneuronal activity was simultaneously recorded at the contralateral hypogiossal nerve roots of the block preparation. Neuronal excitation evoked by stimulation of the NTS area propagated to the VIA4 through the intermediate reticular zone (IRt). In contrast, caudal VI-M stimulation induced excitation propagation to the rostra1 VIM without any clear excitation in the IRt toward the NTS area. NTS stimulation also induced an inspiratory burst discharge in the hypoglossal nerve root activity with a 150-200 ms delay. Fluorescence changes corresponding to the inspiratory burst activity were detected in the VLM which was almost coincidental with the area in which many respiratory neurons had been localized in the previous studies using whole-brainstem preparation; ventral to the nucleus ambiguus or retrofacial nucleus and close to the ventral surface.
1653
BLADDER RESPONSE AND PELVIC NERVE ACTIVITIES INDUCED BY ISOTONIC STIMULATION OF THE BLADDER. MITSUYOSHI SASAKI. Dem. of Phvsiol.. Tokvo Medical Collepe. Tokyo 160. Jaoan
The bladder of a-chloralose anesthetized cat was stimulated isotonically (30-1000 mmHT0, S-10 min). The flow of saline in and out of the bladder was measured with an electromagnetic flow meter. Intravesical pressure was also monitored. In hypogastric nen’e intact or lesioned preparations, active inflow-outflow rhythm was observed. The frequency of this rhythm w’as high (20-30 times per minute). and was closely related to the efferent activities of the vesical branch of the pelvic nerve. When the constant pressure level was increased (typically more than 200 mmHzO), the bladder evacuated the fluid followed by gradual expansion with inflow-outflow rhythm. On the other hand, pelvic nene activities increased.and reached a plateau (no decrease at high pressure as far as 1000 mmH20) when the constant pressure level was increased, suggesting that the central nenous control at high pressure level is primarily excitatory on the bladder, promoting the micturition. When the duration of high constant pressure w’as prolonged, however, intermittent large inflows were observed. Correspondingly, the pelvic neme actit.@ was dramatically decreased in these periods, suggesting the existence of an inhibitory mechanism in the central nemous system, and they were assumed to be related to the relaxation mechanism observed during isovolumic stimulation.
UNILATERAL SENSORIMOTOR RAT. KOICHI Janan.
CEREBELLAL AND SOMATOSENSORY INPUTS TO THE CORTEX OF NEONATALLY CEREBRAL HEMISPHERECTOMIZED FUJIMURA. Dem. of Phvsiol.. Nagasaki Univ. Sch. of Med.. Nagasaki. 852,
It is known that unilateral motor cortex ablation in infancy results in the formation of a rich uncrossed corticospinal projection. The question remains, however, as to the organization of the input to the newly formed corticospinal projection system. In this study, the left fronto-parietal cortex of neonatal rat was aspirated, and after weaning, the rat was trained for getting food pellets by their right forelimb. Two to four months later, evoked potential to electrical stimulation of the cerebellar nuclei and distal forelimb muscles were recorded from the right sensorimotor cortex. The responses were evoked only by stimulation contralateral to the neocortex, although the rat could grasp a small food pellet in its ipsilateral forepaw.
1652
OPI’ICAL IMAGING OF RESPIRATORY BURST ACTIVITY IN MEDULLARY BLOCK PREPARATION FROM NEWBORN RATS. HIROSHI ONIMARU, ARATA KANAMARU AND IKUO HOMMA, Department of Physiologv, Showa University School of Medicine, Hatanodai l-5-8, Shinagawa-ku, Tokyo 142, Japan.
We report here on optical imaging of excitation propagation induced by electrical stimulation of the nucleus tractus solitarius (NTS) area and subsequent inspiratory burst activity in the ventrolateral medulla (VLM) of a medullary block preparation. A medullary block preparation with a thickness of 1.0-1.4 mm, including essential region for respiratory rhythm generation, was isolated from 0- to 4-day-old rats and stained with a fluorescent voltage-sensitive dye, RH795. Neuronal responses in the VLM evoked by electrical stimulation were recorded as a fluorescence change using an optical recording apparatus with a 128 x 128 photodiode array and a maximum time resolution of 0.6 ms (HR Deltaron 1700, Fuji Photo Film Co.). Motoneuronal activity was simultaneously recorded at the contralateral hypogiossal nerve roots of the block preparation. Neuronal excitation evoked by stimulation of the NTS area propagated to the VIA4 through the intermediate reticular zone (IRt). In contrast, caudal VI-M stimulation induced excitation propagation to the rostra1 VIM without any clear excitation in the IRt toward the NTS area. NTS stimulation also induced an inspiratory burst discharge in the hypoglossal nerve root activity with a 150-200 ms delay. Fluorescence changes corresponding to the inspiratory burst activity were detected in the VLM which was almost coincidental with the area in which many respiratory neurons had been localized in the previous studies using whole-brainstem preparation; ventral to the nucleus ambiguus or retrofacial nucleus and close to the ventral surface.
1653
BLADDER RESPONSE AND PELVIC NERVE ACTIVITIES INDUCED BY ISOTONIC STIMULATION OF THE BLADDER. MITSUYOSHI SASAKI. Dem. of Phvsiol.. Tokvo Medical Collepe. Tokyo 160. Jaoan
The bladder of a-chloralose anesthetized cat was stimulated isotonically (30-1000 mmHT0, S-10 min). The flow of saline in and out of the bladder was measured with an electromagnetic flow meter. Intravesical pressure was also monitored. In hypogastric nen’e intact or lesioned preparations, active inflow-outflow rhythm was observed. The frequency of this rhythm w’as high (20-30 times per minute). and was closely related to the efferent activities of the vesical branch of the pelvic nerve. When the constant pressure level was increased (typically more than 200 mmHzO), the bladder evacuated the fluid followed by gradual expansion with inflow-outflow rhythm. On the other hand, pelvic nene activities increased.and reached a plateau (no decrease at high pressure as far as 1000 mmH20) when the constant pressure level was increased, suggesting that the central nenous control at high pressure level is primarily excitatory on the bladder, promoting the micturition. When the duration of high constant pressure w’as prolonged, however, intermittent large inflows were observed. Correspondingly, the pelvic neme actit.@ was dramatically decreased in these periods, suggesting the existence of an inhibitory mechanism in the central nemous system, and they were assumed to be related to the relaxation mechanism observed during isovolumic stimulation.