共查询到20条相似文献,搜索用时 46 毫秒
1.
The adaptation field of the surround mechanism of X and Y retinal ganglion cells in the cat was assessed with variable size, unmodulated adapting spots. Both an on-inhibition measure and an off-discharge measure of surround gain was used. Results suggest that the surround mechanism in Y-cells is strongest in the receptive field middle but weak or nonexistent in the middle of X-cell receptive fields. 相似文献
2.
W. G. Christen R. W. Winters H. I. Cohen T. W. Robertson 《Cellular and molecular life sciences : CMLS》1979,35(10):1350-1351
Summary The adaptation field of the surround mechanism of X and Y retinal ganglion cells in the cat was assessed with variable size, unmodulated adapting spots. Both an on-inhibition measure and an off-discharge measure of surround gain was used. Results suggest that the surround mechanism in Y-cells is strongest in the receptive field middle but weak or nonexistent in the middle of X-cell receptive fields.Acknowledgment. This research was supported by Public Health Service grant No. EY 00701. 相似文献
3.
Bicuculline and picrotoxin block gamma-aminobutyric acid-gated Cl- conductance by different mechanisms 总被引:4,自引:0,他引:4
Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for gamma-aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused. 相似文献
4.
N. Akaike K. Hattori Y. Oomura D. O. Carpenter 《Cellular and molecular life sciences : CMLS》1985,41(1):70-71
Summary Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for -aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused.To whom reprint requests should be addressed.Acknowledgments. We thank Drs S. Minakami and S. Yasui for helpful discussions and comments. 相似文献
5.
R. Spehlmann K. Norcross E. J. Grimmer 《Cellular and molecular life sciences : CMLS》1977,33(5):623-625
Summary Microiontophoretic application of GABA and its antagonist, picrotoxin, altered focal potentials evoked in the caudate nucleus by stimulation near the recording site to a much greater extent than potentials elicited by stimulation of afferent pathways, suggesting that GABA is a transmitter of interneurons in this nucleus.This study was supported by funds from the Veterans Administration and by NIH research grant No. 06820.We thank Kathleen Downes and Clifford Smathers for their assistance. 相似文献
6.
Summary A comparison was made between adaptive and signal sensitivity profiles of the surround response mechanism of cat retinal ganglion
cells. The 2 profiles were found to be similar for X cells but the surrounds of Y cells appear to pool adaptation over a smaller
retinal region than they pool signals.
Acknowledgments. We wish to thank Mr O. Navarro for his valuable technical assistance. This research is supported by Public
Health Service grant No. EY 00701. 相似文献
7.
GABA and its analogues were shown to activate the rabbit corneal endothelial fluid pump in the micromolar range. The stimulation was abolished by bicuculline and chlorpromazine, but not by picrotoxin. 相似文献
8.
The GABA-mimetic activities of 4 analogues muscimol, isonipecotic acid, isoguvacine and N-methyl isoguvacine have been examined at the GABA receptor in the rat isolated superior cervical ganglion. The depolarizing action of all 4 analogues could be selectively antagonized by bicuculline methochloride and isopropyl bicyclophosphate. Muscimol was the only analogue more potent than GABA (molar potency ratio = 5.08 +/- 0.707). The potency of isoguvacine was 0.23 +/- 0.026 and isonipecotic acid 0.011 +/- 0.0028. N-methyl isoguvacine was less than 0.001 GABA. 相似文献
9.
目的 研究糖尿病小鼠视网膜神经无细胞及眼压的变化.方法 5周龄的C57BL/6小鼠腹腔注射链脲佐菌素(STZ)建立糖尿病模型.模型建立后3周和6周,行眼压测量与视网膜神经节细胞计数.结果 与对照鼠相比较,糖尿病小鼠的眼压升高(P<0.01),视网膜神经节细胞比值减少(P<0.01).结论 糖尿病会导致小鼠视网膜神经节细胞的减少和眼压升高,这些病理改变可能是糖尿病视网膜病变的重要组成部分. 相似文献
10.
N. G. Bowery J. F. Collins A. L. Hudson M. J. Neal 《Cellular and molecular life sciences : CMLS》1978,34(9):1193-1195
Summary The GABA-mimetic activities of 4 analogues muscimol, isonipecotic acid, isoguvacine and N-methyl isoguvacine have been examined at the GABA receptor in the rat isolated superior cervical ganglion. The depolarizing action of all 4 analogues could be selectively antagonized by bicuculline methochloride and isopropyl bicyclophosphate. Muscimol was the only analogue more potent than GABA (molar potency ratio=5.08±0.707). The potency of isoguvacine was 0.23±0.026 and isonipecotic acid 0.011±0.0028. N.-methyl isoguvacine was <0.001 GABA. 相似文献
11.
N. Davidson Edna I. Macfarlane Diane L. Michie 《Cellular and molecular life sciences : CMLS》1977,33(7):935-936
Summary The effects of 2 of a series of bicyclic phosphorous esters, the ethyl (EPTBO) and isopropyl (IPTBO) compounds, were compared with those of the GABA antagonists, picrotoxin and bicuculline, on presynaptic inhibition in the rat cuneate nucleus. Both EPTBO and IPTBO were found to be effective, reversible antagonists of presynaptic inhibition, with IPTBO approximately 10 times more potent than EPTBO and equipotent with bicuculline, EPTBO equipotent with picrotoxin.The authors are grateful to Dr J. F. Collins, Department of Chemistry, Sir John Cass School of Science and Technology, 31 Jewry Street, London, for the gift of bicyclic phosphorous esters. 相似文献
12.
Summary GABA and its analogues were shown to activate the rabbit corneal endothelial fluid pump in the micromolar range. The stimulation was abolished by bicuculline and chlorpromazine, but not by picrotoxin.This work was supported by PHS-NIH Grant No. 1R01 EY 00965, to S.D. 相似文献
13.
G. J. Leitch D. J. Backes F. S. Siegman G. D. Guthrie 《Cellular and molecular life sciences : CMLS》1977,33(4):496-498
Summary Rat cerebellar GABA levels were reduced following 2 weeks alcohol administration. Animals also exhibited alcohol tolerance with an air righting reflex. This tolerance was mimiced by picrotoxin administration in control animals and was reduced in animals chronically administered alcohol by aminooxyacetic acid.This work was supported in part by a grant awarded under Public Law 93-282, Division of Addiction Services, Indiana Department of Mental Health, Indianapolis, Indiana, USA, Patrick J. V. Corcoran, M. D., principal investigator. 相似文献
14.
Maintained firing rates of X cells and Y cells were compared at 6 adaptation levels (AL) between -2.71 log cd/m2 and 2.28 log cd/m2 (10 mm2 pupil size). X cell maintained firing was higher at all ALs and was statistically different at medium and high ones. Changes in AL had nearly identical effects upon X and Y cell suprathreshold sensitivity to a flashing spot in the center of their receptive fields; the Weber function had a slope of 0.744 for Y cells and 0.743 for X cells. These values are not statistically different. 相似文献
15.
J. Trifonow M. A. Ostrowski P. Dettmar 《Cellular and molecular life sciences : CMLS》1969,25(4):370-371
Summary Application of ACh on the isolated perfused retina of the frog elicited spikes of the optic nerve. The extent of this spike activity depended on the amount of ACh applied. The retinal response to ACh was varied by prostigmine and atropine as expected by their pharmacological properties. From these experiments it cannot be concluded that ACh is acting on the synapses of the firing ganglion cells directly. 相似文献
16.
Summary Maintained firing rates of X cells and Y cells were compared at 6 adaptation levels (AL) between –2.71 log cd/m2 and 2.28 log cd/m2 (10 mm2 pupil size). X cell maintained firing was higher at all ALs and was statistically different at medium and high ones. Changes in AL had nearly identical effects upon X and Y cell suprathreshold sensitivity to a flashing spot in the center of their receptive fields; the Weber function had a slope of 0.744 for Y cells and 0.743 for X cells. These values are not statistically different.This research is supported by Public Health Service grant no. EY 00701. 相似文献
17.
Sergio Claudio Saccà Alberto Izzotti 《Cellular and molecular life sciences : CMLS》2014,71(12):2197-2218
Primary open-angle glaucoma is a multifactorial disease that affects the retinal ganglion cells, but currently its therapy is to lower the eye pressure. This indicates a definite involvement of the trabecular meshwork, key region in the pathogenesis of glaucoma. This is the first target of glaucoma, and its functional complexity is a real challenge to search. Its functions are those to allow the outflow of aqueous humor and not the reflux. This article describes the morphological and functional changes that happen in anterior chamber. The “primus movens” is oxidative stress that affects trabecular meshwork, particularly its endothelial cells. In these develops a real mitochondriopaty. This leads to functional impotence, the trabecular meshwork altering both motility and cytoarchitecture. Its cells die by apoptosis, losing barrier functions and altering the aqueous humor outflow. All the morphological alterations occur that can be observed under a microscope. Intraocular pressure rises and the malfunctioning trabecular meshwork endotelial cells express proteins that completely alter the aqueous humor. This is a liquid whose functional proteomics complies with the conditions of the trabecular meshwork. Indeed, in glaucoma, it is possible detect the presence of proteins which testify to what occurs in the anterior chamber. There are six classes of proteins which confirm the vascular endothelium nature of the anterior chamber and are the result of the morphofunctional trabecular meshwork decay. It is possible that, all or in part, these proteins can be used as a signal to the posterior pole. 相似文献
18.
19.
Summary The action potentials of optic nerve fibres in cats were stereotactically recorded (light pentobarbital anaesthesia, Curarin-immobilization). The activation of retinal neurons stimulated by light spots within the receptive field centre was a non-linear function of the sinusoidal intensity modulation of the stimuli. 相似文献
20.
Over the last ten years there has been growing acceptance that retinal photoreception among mammals extends beyond rods and
cones to include a small number of intrinsically photosensitive retinal ganglion cells (ipRGCs). These ipRGCs are capable
of responding to light in the absence of rod/cone input thanks to expression of an opsin photopigment called melanopsin. They
are specialised for measuring ambient levels of light (irradiance) for a wide variety of so-called non-image-forming light
responses. These include synchronisation of circadian clocks to light:dark cycles and the regulation of pupil size, sleep
propensity and pineal melatonin production. Here, we provide a review of some of the landmark discoveries in this fast developing
field, paying particular emphasis to recent findings and key areas for future investigation. 相似文献