Acid- Base Chemistry Titration With the help of computer-interfaced pH probes, you will investigate the qualitative and quantitative aspects of acid-base reactions.
In this work we investigated the mechanisms underlying melatonin-induced potentiation of glycine currents in rat retinal ganglion cells RGCs. Immunofluorescence double labelling showed that rat RGCs were solely immunoreactive to melatonin MT2 receptors.
The protein kinase C PKC activator PMA potentiated the glycine currents and in the presence of PMA melatonin failed to cause further potentiation of the currents, whereas application of the PKC inhibitor bisindolylmaleimide IV abolished the melatonin-induced potentiation. Furthermore, in rat retinal slices melatonin potentiated light-evoked glycine receptor-mediated inhibitory postsynaptic currents in RGCs.
These results suggest that melatonin, being at higher levels at night, may help animals to detect positive or negative contrast in night vision by modulating inhibitory signals largely mediated by glycinergic amacrine cells in the inner retina.
Introduction Melatonin is known to regulate various physiological functions by activating specific receptors, namely MT1, MT2 and MT3 subtypes Vanecek, ; Dubocovich et al.
In the vertebrate retina melatonin is synthesized and released by photoreceptors and may be implicated in retinomotor responses, rod disc shedding, phagocytosis, etc.
It has been recently shown that melatonin plays neuromodulatory roles in the retina, like those observed in suprachiasmatic nucleus SCN McArthur et al.
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In the outer retina, melatonin modulates the function of cone-driven horizontal cells in teleost fish directly by altering AMPA receptor-mediated currents of these cells through the activation of MT1 receptors Huang et al.
Most recently, it is reported that melatonin potentiates rod signals to ON-type bipolar cells in carp by modulating the activity of the metabotropic glutamate receptor expressed on these cells through the activation of MT2 receptors Ping et al.
In the inner retina, retinal ganglion cells RGCswhich are output neurons in the retina, receive inhibitory GABAergic and glycinergic inputs from amacrine cells, which shape their responses driven by excitatory input from bipolar cells Protti et al.
All three subtypes of melatonin receptors are found in RGCs in a variety of species Fujieda et al. Indeed, previous work in this laboratory demonstrated that melatonin potentiates glycine receptor-mediated currents in rat RGCs by activating MT2 receptors Zhang et al.
However, the mechanisms underlying this melatonin effect are still unclear. Accumulating evidence also suggests that, following activation of MT2 receptors, phospholipase C PLC -dependent pathways could come into play McArthur et al. During this study all efforts were made to minimize the number of animals used and their suffering.
In the present work, a total of 78 rats were used, among which were 52 for dissociated cell electrophysiological recordings; 8 for electrophysiological recordings in retinal slices; 6 for calcium imaging; and 12 for immunocytochemistry and Western blots.
A detailed description of anaesthetic regime follows. After a survival period of 5—7 days, RGCs were clearly labelled for immunocytochemical analysis. The retinas were then digested in 1. RITC-labelled RGCs, showing red fluorescence, were chosen for whole-cell patch-clamp recording within 2—3 h after dissociation.
Western blot analysis and immunocytochemistry Rat retinal extracts were prepared following the procedure described in detail previously Chen et al.
The extract samples 2. The blots were washed and incubated with horseradish peroxidase-conjugated donkey anti-goat IgG 1: Immunocytochemistry of isolated retinal cells refers to Yu et al. To avoid any possible reconstruction stacking artifact, double labelling was precisely evaluated by sequential scanning on single-layer optical sections at intervals of 1.
Whole-cell patch-clamp recordings The dissociated cells were bathed in Ringer solution containing mm: Fast capacitance was fully cancelled and cell capacitance was partially cancelled by the circuits of the amplifier as much as possible.
Seventy per cent of the series resistance of the recording electrode was compensated. Commonly, data were acquired by using Pulsefit 8.Experiments To Accompany Quantitative Chemical Analysis, 6th Edition () your laboratory.
References to many additional experiments published in recent years in the Calculate the molarity of Ca2+ in the unknown solution or the weight percent of Ca in the.
The experiment will be conducted in three trials and each trial will be duplicated.
The first trial will serve as a baseline for comparison. In the second trial, the student will reduce the iodate concentration by half leaving the bisulfate concentration the same as in the baseline trial and determine . calculate the pKa (and thus Ka) of an acid. At the equivalence point, the volume of base added At the equivalence point, the volume of base added is just enough to exactly neutralize all of the acid.
Mar 16, · Experiment 1: Acid Base Experiment. The purpose of acid base laboratory experiment was to determine equivalance points.
pKa points for a strong acid. HCl, titrated with a strong base, NaOH using a drop approach in order to determine completely accurate data. The pH is measured every time 1ml of NaOH timberdesignmag.com: group 4 biochem. 1 Determining the pK a’s of glycine Student worksheet Health and safety note Wear eye protection.
− mol dm 3 sodium hydroxide solution and mol dm−3 nitric acid are irritant. Principle Glycine (figure 1) is an amino acid. The number of pKa values differentiates polar and nonpolar amino acids from charged amino acids.
The position of the pKa values for charged amino acids allows one to identify positively charged from negatively charged amino acids. Comparisons between experimental and literature pKa values can allow the identification of a specific amino acid.