Analysis of synaptic inputs to chromaticity-type horizontal cells in CARP and turtle retinas

s140

A FIBER PATHWAY IN THE CORPUS CALLOSUM FROM THE VESTIBULAR CORTICAL AREA OF THE CAT: A WGA-HRP STUDY TAKASHI KAWASHIMA*', HIROTAKA SATAKE*', KEN'ICHI MATSUNAMI', MASATAKA m2, MASAFUMI FUJITA' AND SHIGEYUKI DEURA ____Res. Gifu Univ. ___Scho~~~n~,N~~~~,o~Y~~~~' Inst. of Equilibrium d 3- Dep. of Anat. , Gifu Univ. School of Med., Gifu City 500, Japan and __The site of fiber pathways in the corpus callosum from the vestibular cortical area (2~) was studied in cat (n=13) using WGA-HRP methods. WGA-HRP (4%) was injected in the vestibular cortical area (A=16,L=14) in reference to the anterior suprasylvian sulcus, using a microsyringe (Hamilton, or Ito Co.; under anesthetic conditions with ketamine (20 mg/Kg body weight). 1 pl), After three days, the cat was anesthetized and perfused intracardially with buffered saline, glutaraldehyde, paraformaldehyde, and 30% sucrose. The sections were made (80 pm). HRP was brain was removed, from which sagittal reacted with the standard method to allow visualization. The site of the callosal fiher pathway in the corpus callosum thus determined was in the anterior part of the middle third of the corpus callosum. A slight individual variation seems to exist In the site of the callosal fiber pathway.

44. Visual system

I. Retina

GLYCINE AND GABA RECEPTORS SABUROSUKE Glycine

SUZUKI*, National

and GABA

and the response terminal,

(papain)

of the retina

nor picrotoxin.

with a smaller

maintained

on bipolar

Sciences,

increase

in chloride

drug application.

wild (C57BL/6J)

responses

currents

response

amplitude

ANALYSIS OF SYNAPTIC INPUTS TURTLE RETINAS. EI-ICHI Physioloqy, Keio University Tokyo 160, Japan

suggest

that glycine

and GABA act on separate

patch clamp. but by neither

(competitively)

cells of the spastic dose) than

mutant

cells by enzymatic

by 10 nM strychnine,

GABA was equally

at axon

for glycine

(spa/spa)

bipolar

by 30 PM bicuculline Bipolar

to a saturating

identical.

receptors

or spastic

solitary

to glycine

high sensitivity

of these cells by whole-cell

were antagonized

were antagonized

of glycine was almost

and wild mice. These observations

conductance,

We obtained

responses

The response

We asked whether

cells of the adult

the membrane

444, Japan.

cells of the mouse retina.

but not by 100 nM strychnine.

(maximal

AKIMICHI KANEKO AND Okazaki

glycine receptors.

and measured

GABA-induced

V,,,

in bipolar

characteristics:

during

(non-competitively),

but the least effective concentration spastic

responses

cells of the wild mouse, glycine-induced

30 PM picrotoxin to glycine

molecules

for Physiological

known to have low-density

dissociation

bicuculline

desensitization

are different

mice, biochemically

In bipolar

inhibitory

to GABA have similar

and rapid

and GABA

induce

OF MOUSE BIPOLAR CELLS.

Institute

and

mouse responded

cells of the wild mouse, potent

to bipolar

receptor

cells of

molecules.

TO CHROMATICITY-TYPE HORIZONTAL CELLS IN CARP AND AND MOTOHIKO MURAKAMI, Department of MIYACHI School of Medicine, Shinanomachi 35, Shinjuku-ku,

In the 1988 Meeting, we reported that intracellular injection of CAMP and dibutyryl-CAMP and &3-bromo-CAMP, into luminosity-type (Hl) its analogues, horizontal cells caused a significant increase in the input resistance, because the gap junctions between cells were blocked. Similar experiments were performed on H2 and H3 chromaticity-type horizontal cells in carp and turtle thus Input resistance increases were similarly observed, cells could retinae. be easily polarized by intracellular current injection. In H2 cells, a hyperpolarizing response to green light and a depolarizing one to red light were In turtle H2 cells, both light both reduced by depolarizing current injection. responses of opposite polarity were successfully reversed by further depolarization. Reversal potentials of the responses to both green and red lights coincided at about 0 mV. These reversal potential values were the same as observed in light responses in carp and turtle Hl cells, strongly suggesting that the ionic mechanisms of synaptic transmission are common among horizontal cell types.