1. Cells in the ganglion cell layer of salamander retinal slices were voltage clamped using patch pipettes. Light elicited transient excitatory postsynaptic currents (EPSCs) in on‐off ganglion cells and sustained EPSCs in on ganglion cells. Light‐evoked inhibitory postsynaptic currents in these cells could be blocked by 100 microM‐bicuculline methobromide and 500 nM‐strychnine. 2. In the presence of external Cd2+, at a concentration that blocked light‐evoked synaptic inputs, N‐methyl‐D‐aspartate (NMDA) and the non‐NMDA‐receptor agonists, quisqualate and kainate, gated conductances in both on‐off and on ganglion cells. The current‐voltage (I‐V) curve for the conductance elicited by NMDA had a negative slope between ‐40 and ‐70 mV and a reversal potential near 0 mV. The I‐V curves for the non‐NMDA‐receptor‐mediated conductances were nearly linear and also had reversal potentials near 0 mV. 3. I‐V curves were measured at an early time point near the peak of transient EPSCs and at a later time point during the decay phase of the responses. The late I‐V curve had a negative slope below ‐40 mV. The early I‐V curve had a positive slope over the entire voltage range but the slope was greater at positive than at negative potentials. The evoked current reversed near 0 mV at both time points. 4. The region of negative slope of the late I‐V curve was eliminated when Mg2+ was removed from the external saline. A slowly decaying component of transient EPSCs was eliminated in 20 microM‐DL‐2‐amino‐7‐phosphonoheptanoate (AP7), an NMDA‐receptor antagonist. 5. Application of 1 microM‐6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), a non‐NMDA‐receptor antagonist at this concentration, blocked a fast component of transient EPSCs. 6. Our results demonstrate that the synaptic inputs to on‐off ganglion cells have two components: a slower NMDA‐receptor‐mediated component having a time‐to‐peak of 110 +/‐ 45 ms and an e‐fold decay time of 209 +/‐ 35 ms at ‐31 mV (mean +/‐ S.D., n = 5), and a faster non‐NMDA‐receptor‐mediated component having a time‐to‐peak of 28 +/‐ 10 ms and an e‐fold decay time of 43 +/‐ 20 ms at ‐31 mV (n = 8). 7. A similar analysis of sustained EPSCs of on ganglion cells showed that these currents resulted from sustained activation of both NMDA and non‐NMDA receptors.
The Journal of Physiology – Wiley
Published: Sep 1, 1990
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera