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Voltage-gated ionic currents in isolated retinal horizontal cells of the cat
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VOLTAGE-GATED IONIC CURRENTS IN ISOLATED RETINAL HORIZONTAL CELLS OF T H E C A T . YOSttIKI WEDA, AKIMICHI KANEKO and MAKOTO KANEDA, Department of Information Physiology, National Institute for Physiological Sciences, Okazaki, 444 Japan. Many reports have been made on the voltage-gated and agonist-gated membrane currents of horizontal cells isolated from the retina of various fishes, but studies on horizontal cells of mammalian retina are quite scarce. In the present study we analyzed the ionic conductance of the cat horizontal cells and compared the type and amplitude of the voltage-gated ionic currents with those reported in the goldfish horizontal cell. The isolated cat retina was incubated in oxygenated saline containing 4 u n i t / m l papain for 60 min at 28 °C, and cells were mechanically dissociated. Two morphologically different horizontal cells were identified; type A and type B cells (Boycott et a1..1978). The type A cell has 4 - 5 thick main dendrites which run as long as 100 pm. The type B cell has many (>10) fine dendrites nearly 30/~m long. The type B cell axon terminal was not found. Membrane currents were recorded under voltage-clamp conditions. Each current component was isolated by adding selective blockers or by ion substitution. The resting potentials were similar in both type A and type B cells (approximately -45 mV), but the input capacitance was larger in A (105 pF, n = 32) than in B (40 pF, n = 17), reflecting the size difference. The type A cell had five types of voltage-gated ionic currents: Ilv,, Ic, (L-type), I,,~,~z (the inward rectifier), Ia (the transient outward) and IK(,) (the delayed rectifier). T h e type B cells had all those current except for IN=. The types of ionic currents were the same in both goldfish and cat. Different from the goldfish, Ia was very prominent among the five types of ionic currents in the cat horizontal cell.
41. Visual system. II. Anatomy and physiology RETINAL PROJECTIONS INTO THE DIENCEPHALON IN THE FO~L(GALLUS GALLUS DOMESTICUS). SHOEI SUGITA, L a b o r a t o r y o f A n i m a l A n a t o m y a n d P h y s i o l o g y , Faculty of Agriculture, Utsunomlya University 35B M l n e m a c h l U t s u n o m i y a 3 2 1 , J a p a n . The localization of the primary visual centers in the hen dlencephalon was determined by anterograde transport horseradish peroxldase (HRP) techniques. Twelve birds w e r e u s e d f o r HRP s t u d y a n d t h r e e w e r e u s e d for cytoarchltectural study (Nissl stained preparation). T h i r t y p e r c e n t HRP s o l u t i o n (100 pl) was injected Into the vitreous body of unilateral eye under anethesla of sodium pentobarbital (3~ m g / k g ) . A f t e r a p o s t o p e r a t i v e p e r i o d o f 48 h o u r s , t h e animals were deeply anesthetized and perfused intracardlally w l t h I% g l u t a r a l d e h y d e and 1.25~ paraformaldehyde in phosphate buffer (pH 7 . 4 ) . T h e b r a i n was c u t i n t o s e r i a l transverse sections. In the hypothalamic region, retinal projections were found in the contralateral medial (medial retlnoreclplent hypothalamlc nucleus) and lateral (lateral retlnoreciplent hypothalamic nucleus) hypothalamlc area. In the thalamus, Iabeled terminals were found in the lateral geniculate nucleus, the lateral part of dorsolateral thalamus the medlal part of dorsolateral thalamus, the ventrolateral thalamus (VL÷), the rostrolateral part of dorsolateral anterior thalamus, the magnocellular part of dorsolateral anterior thalamus, the lateral anterior thalamus, the ectomammillary nucleus, the external nucleus, and the superficial synencephallc nucleus, contralaterally. In p a r t i c u l a r , there were terminals w h i c h l o o k e d l i k e i s l a n d i n t h e m i d d l e p a r t o f VLT.
PROJECTIONS TO THE THALAMUS AND MIDBRAIN OF SINGLE LABELED RETINAL AXONS IN THE CAT. NOBUAKI TAMAMAKI. DANIEL J_ UHLRICH*. and S.MURRAY SHERMAN*. D o o r . o f A n a t o m y , E u k u l M e d i c a l S c h o o l . F u k u l 9 1 0 - 1 1 J a o a n and D o o r . ~ Naurnbloloav ~ Behavior. SUNY a t S t o n y B r o o k = S t o n y B r o o k = ~ 11794 U . S . A . "~ The r e t i n a directly innervates visual centers In t h e t h a l a m u s and m i d brain. To c l a r i f y the proJection pattern of single axons to these targets we used l n t r a - a x o n a l labeling method with blocytln In c a t s . We h a ve r e c o v e r e d and r e c o n s t r u c t e d 14 r e t i n a l Y a x o n s and 5 X a x o n s . E v e r y X and Y a x o n I n n e r vated the dorsal lateral genlculate nucleus (dLGN), medial Interlamlnar nucleus ( M I N ) , and p r e t e c t u m . E v e r y X sxon I n n e r v a t e d only the rostral subnuclsus of the pretectum, while Y axons Innervated all subnuclel. Almost all of the Y axons also innervated the superior colllculus (SC). T h e r e was e x c e l l e n t retlnotople correspondence between LGN and SC t e r m i n a l zones; rstlnotopy for the pretectal z o n e s was u n c l e a r . Each Y a xo n f r o m t h e I p s l l a t e r a l eye formed a single, circular puff In t h e SC, w h i l e each from the contralateral eye extended further medlolaterally and d o r s o v e n t r a l l y . For the Y axons, there was a n e g a t i v e correlation between receptive field eccentricity and t h e t o t a l number o f t e r m i n a l boutons. This suggests a negative correlation between the size of alpha cell s o m a t a and t h e i r termlnal axon a r b o r s .
VOLTAGE-GATED IONIC CURRENTS IN ISOLATED RETINAL HORIZONTAL CELLS OF T H E C A T . YOSttIKI WEDA, AKIMICHI KANEKO and MAKOTO KANEDA, Department of Information Physiology, National Institute for Physiological Sciences, Okazaki, 444 Japan. Many reports have been made on the voltage-gated and agonist-gated membrane currents of horizontal cells isolated from the retina of various fishes, but studies on horizontal cells of mammalian retina are quite scarce. In the present study we analyzed the ionic conductance of the cat horizontal cells and compared the type and amplitude of the voltage-gated ionic currents with those reported in the goldfish horizontal cell. The isolated cat retina was incubated in oxygenated saline containing 4 u n i t / m l papain for 60 min at 28 °C, and cells were mechanically dissociated. Two morphologically different horizontal cells were identified; type A and type B cells (Boycott et a1..1978). The type A cell has 4 - 5 thick main dendrites which run as long as 100 pm. The type B cell has many (>10) fine dendrites nearly 30/~m long. The type B cell axon terminal was not found. Membrane currents were recorded under voltage-clamp conditions. Each current component was isolated by adding selective blockers or by ion substitution. The resting potentials were similar in both type A and type B cells (approximately -45 mV), but the input capacitance was larger in A (105 pF, n = 32) than in B (40 pF, n = 17), reflecting the size difference. The type A cell had five types of voltage-gated ionic currents: Ilv,, Ic, (L-type), I,,~,~z (the inward rectifier), Ia (the transient outward) and IK(,) (the delayed rectifier). T h e type B cells had all those current except for IN=. The types of ionic currents were the same in both goldfish and cat. Different from the goldfish, Ia was very prominent among the five types of ionic currents in the cat horizontal cell.
41. Visual system. II. Anatomy and physiology RETINAL PROJECTIONS INTO THE DIENCEPHALON IN THE FO~L(GALLUS GALLUS DOMESTICUS). SHOEI SUGITA, L a b o r a t o r y o f A n i m a l A n a t o m y a n d P h y s i o l o g y , Faculty of Agriculture, Utsunomlya University 35B M l n e m a c h l U t s u n o m i y a 3 2 1 , J a p a n . The localization of the primary visual centers in the hen dlencephalon was determined by anterograde transport horseradish peroxldase (HRP) techniques. Twelve birds w e r e u s e d f o r HRP s t u d y a n d t h r e e w e r e u s e d for cytoarchltectural study (Nissl stained preparation). T h i r t y p e r c e n t HRP s o l u t i o n (100 pl) was injected Into the vitreous body of unilateral eye under anethesla of sodium pentobarbital (3~ m g / k g ) . A f t e r a p o s t o p e r a t i v e p e r i o d o f 48 h o u r s , t h e animals were deeply anesthetized and perfused intracardlally w l t h I% g l u t a r a l d e h y d e and 1.25~ paraformaldehyde in phosphate buffer (pH 7 . 4 ) . T h e b r a i n was c u t i n t o s e r i a l transverse sections. In the hypothalamic region, retinal projections were found in the contralateral medial (medial retlnoreclplent hypothalamlc nucleus) and lateral (lateral retlnoreciplent hypothalamic nucleus) hypothalamlc area. In the thalamus, Iabeled terminals were found in the lateral geniculate nucleus, the lateral part of dorsolateral thalamus the medlal part of dorsolateral thalamus, the ventrolateral thalamus (VL÷), the rostrolateral part of dorsolateral anterior thalamus, the magnocellular part of dorsolateral anterior thalamus, the lateral anterior thalamus, the ectomammillary nucleus, the external nucleus, and the superficial synencephallc nucleus, contralaterally. In p a r t i c u l a r , there were terminals w h i c h l o o k e d l i k e i s l a n d i n t h e m i d d l e p a r t o f VLT.
PROJECTIONS TO THE THALAMUS AND MIDBRAIN OF SINGLE LABELED RETINAL AXONS IN THE CAT. NOBUAKI TAMAMAKI. DANIEL J_ UHLRICH*. and S.MURRAY SHERMAN*. D o o r . o f A n a t o m y , E u k u l M e d i c a l S c h o o l . F u k u l 9 1 0 - 1 1 J a o a n and D o o r . ~ Naurnbloloav ~ Behavior. SUNY a t S t o n y B r o o k = S t o n y B r o o k = ~ 11794 U . S . A . "~ The r e t i n a directly innervates visual centers In t h e t h a l a m u s and m i d brain. To c l a r i f y the proJection pattern of single axons to these targets we used l n t r a - a x o n a l labeling method with blocytln In c a t s . We h a ve r e c o v e r e d and r e c o n s t r u c t e d 14 r e t i n a l Y a x o n s and 5 X a x o n s . E v e r y X and Y a x o n I n n e r vated the dorsal lateral genlculate nucleus (dLGN), medial Interlamlnar nucleus ( M I N ) , and p r e t e c t u m . E v e r y X sxon I n n e r v a t e d only the rostral subnuclsus of the pretectum, while Y axons Innervated all subnuclel. Almost all of the Y axons also innervated the superior colllculus (SC). T h e r e was e x c e l l e n t retlnotople correspondence between LGN and SC t e r m i n a l zones; rstlnotopy for the pretectal z o n e s was u n c l e a r . Each Y a xo n f r o m t h e I p s l l a t e r a l eye formed a single, circular puff In t h e SC, w h i l e each from the contralateral eye extended further medlolaterally and d o r s o v e n t r a l l y . For the Y axons, there was a n e g a t i v e correlation between receptive field eccentricity and t h e t o t a l number o f t e r m i n a l boutons. This suggests a negative correlation between the size of alpha cell s o m a t a and t h e i r termlnal axon a r b o r s .