Tilled water. To each tube, 0.four ml of 20 mM N,N-dimethyl-p-phenylenediamine sulfate in 7.2 M HCI was added, quickly followed by the addition of 0.4 ml of 30 mM FeCI, in 1.2 M HCI. Just after 20 min of incubation at area temperature, the absorbance from the resulting option at 670 nm was measured with a spectrophotometer. All assays have been done in duplicate. The calibration curve of absorbance versus sulfide concentration was made by using defined concentrations ofThis perform was supported by grants in the National Institutes of Well being (NIH) to Dr. David Schubert (ROINSU9658) and from the NIH (R29NS31202) and also the Alzheimeis Association to H.K. K.A. was supported by NIH Grant ROINS09658. WC thank Dr. J. P. Kraus to get a CBS cDNA plasmid and Dr. P. F. Erickson for a CSE cDNA plasmid. We thank Drs. D. Schubert, J. P. Kraus. and P. F. Erickson for discussions. We also thank Drs. D. Schubert, T. Saitoh, Y. Goda, Y. Sagara, and P. Maher for readine this manuscriot. Correspondence should he aidrrased to Hideo Kimura, The Salk Institute for Biological Studies, P.0. Box X.5800, San Diego, CA 92138. Copyright 0 lYY6 Society for Neuroscience 0270.350498-98-5 site 6474/96/161066-06 05.00/AbeandKimuralHydrogenSulfideas an EndogenousNeuromodulatorJ. Neurosci.,February1, 1996,76(3):1066-sodium hydrosulfide (NaHS) answer. A stock option of NaHS (one hundred mM) was prepared by dissolving NaHS compensated using the ratio of NaHS/H,O instantly just before use. Elecrrophysiology. Hippocampal slices (400-450 pm) have been prepared from Sprague-Dawley rats (3-6 weeks old for LTP experiments and 12-15 d old for whole-cell recordings) and maintained within a chamber (1.5-Chloro-1H-pyrazolo[4,3-d]pyrimidine Data Sheet 5 ml) at 34″C, exactly where they have been constantly perfused with artificial CSF (ACSF) consisting of (in mM): 124 NaCl, four KCI, two.PMID:33729055 4 CaCl,, 1.three MgSO,, 1.24 NaH,POd, 26 NaHCO,, and ten glucose, bubbled with 95 O,/a r.`ii ETE g5 co,. – _A bipolar stimulating electrode was placed in the stratum radiatum inside the CAl/CA2 border area, and the evoked EPSP along with the population snike have been extracellularly recorded from the stratum radiatum and also the pyramidal cell layer within the CA1 area, respectively, using a glass capillary microelectrode (3-5 Ma) filled with 0.9 NaCI. A single test stimulation (0.1 msec duration) was applied at intervals of 20 sec. The stimulus intensity was adjusted inside the range of 35-55 /.LA to evoke 0.8-1.0 mV on the field EPSPs, and inside the array of 50-100 PA which induce 50 from the maximum amplitude for the population spikes. Adjustments in field possible had been recorded in present clamp mode with an Axopatch 200A amplifier (Axon Instruments. Foster Citv. CA) and digitized using a DigiData 1200 r log-to-digital converter (Axon Instruments). Nine consecutive records had been averaged, along with the data have been stored on a pc (Date1 486, San Diego, CA). To induce potentiation of evoked field potentials, a tetanic stimulation was applied at the identical intensity using the test stimulation for the population spikes and at twice as significantly intensity for field EPSPs. Nine consecutive records have been averaged and the information were collected at intervals of 3 min. After all LTP experiments, a robust tetanic stimulation (one hundred pulses at one hundred Hz, twice at an interval of 20 set) was applied to determine whether slices were capable to induce LTP. To record membrane currents induced by NMDA or AMPA, wholecell patch recording was performed in CA1 pyramidal neurons in hippocampal slices. Patch electrodes (4-4.5 MR) had been filled with an internal solution consisting of (in mM): 11.