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At least 577 records · Page 32Linked to original sources
PubMed1994

Glycine response in acutely dissociated ventromedial hypothalamic neuron of the rat: new approach with gramicidin perforated patch-clamp technique.

1. We investigated the glycine-induced response in ventromedial hypothalamic (VMH) neurons freshly dissociated from 8- to 12-day-old rats using the nystatin and gramicidin perforated patch recording modes. The nystatin-formed pores in the plasma membrane are permeable for both monovalent cations and anions, whereas those formed by gramicidin are permeable only to monovalent cations. Therefore, when the patch-pipette contains 150 mM Cl- and gramicidin, the physiological intracellular Cl- concentration ([Cl-]i) is undisturbed in the cell-attached condition of the pipette. 2. At holding potentials of -40 to -60 mV, glycine induced inward currents and outward currents in the nystatin and gramicidin perforated patch recording modes, respectively. The values of the half-maximum effective concentration (EC50) and the Hill coefficient in the concentration-response relationships of the glycine responses were 2.9 x 10(-5) M, 1.1, and 4.2 x 10(-5) M, 1.4, respectively. These values were quite similar in both recording modes. 3. The reversal potentials of the glycine responses (EGly) were -1.5 mV in the nystatin perforated patch recording and -75.0 to -24.8 mV in the gramicidin perforated patch recording. 4. Strychnine (3 x 10(-8) M) inhibited the glycine-induced outward currents in a competitive manner and the half-inhibition concentration (IC50) of strychnine on the 10(-4) M glycine-induced response was 1.9 x 10(-8) M. 5. The physiological [Cl-]i in the VMH neurons calculated from the EGly obtained by the gramicidin perforated patch mode ranged from 6.0 to 43.8 mM (n = 28).

Animals↗
PubMed2003

Glycine facilitates transmitter release at developing synapses: a patch clamp study from Purkinje neurons of the newborn rat.

Synaptic currents in immature Purkinje cells from rats on postnatal days 0-14 (P0-P14) were studied using whole-cell patch-electrodes applied to cerebellar slices (200 micro m in thickness). Purkinje cells (held at -40 mV) showed excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs) spontaneously. From P2 to P12 the frequencies of miniature EPSCs and miniature IPSCs in the Purkinje cells increased by 10-fold or more, suggesting progressive formation of functional synapses during this period. Application of glycine (100 micro M) to an immature Purkinje cell at P3-10 immediately increased the frequencies of both EPSCs and IPSCs. The effects of glycine showed maximum at P5-6 for EPSCs and at P9-10 for IPSCs and decreased thereafter. Facilitatory effects of glycine were suppressed by strychnine (1 micro M), a specific blocker of the ionotropic glycine receptor, while the effects were also induced by other glycinergic agonists, including alpha-L-alanine (1 mM), L-serine (1 mM) and taurine (500 micro M). The site of glycinergic effects was studied by removing the action potential generation in cerebellar slices. Following the addition of tetrodotoxin (TTX, 1 micro M), the glycine-induced facilitation of EPSC almost disappeared, while that of IPSC remained (i.e. miniature IPSCs) and reached more than half of the value without TTX. These findings suggest that the ionotropic glycinergic receptors are expressed transiently but profoundly in the developing cerebellum, and that the distributions of these receptors causing excitation are different at excitatory and inhibitory presynaptic neurons. The glycine receptors may play distinct roles in the maturation and organization of cerebellar neural circuits.

Acetylcholine↗
PubMed1994

Patch-clamp analysis of hypoglycemia-induced inhibition of synaptic transmission in the rat dorsolateral septal nucleus.

The role of glucose in neuronal transmission was examined in the rat dorsolateral septal nucleus (DLSN) by using 'slice-patch' techniques. Removal of glucose from the oxygenated Krebs solution produced an outward current associated with an increased K+ conductance. The glucose-depletion depressed the excitatory postsynaptic current (EPSC), the inhibitory postsynaptic current (IPSC) and the late hyperpolarizing current (LHC) produced by stimulation of the fimbria/fornix pathway. It is hypothesized that glucose regulates neurotransmission in the rat DLSN by modulating the release of transmitters from presynaptic nerve terminals.

Animals↗
PubMed1999

Practical limits on the maximal speed of solution exchange for patch clamp experiments.

Studying ligand-gated ion channels often requires the ability to change solutions quickly. Using finite element models, I have examined the practical limitations of how fast solutions can be exchanged on an outside-out patch using a dual stream switcher. The primary factors controlling the speed of response are the flow velocity, proximity of the patch to the exit ports, the width of the partition between the two streams, the velocity with which the streams can be moved across the patch, and the viscosity of the solutions. The practical limit seems to be a rise time of approximately 20 microseconds. The rate-limiting step is the velocity of the (usually piezo) motor that translates the streams across the patch. Increasing the perfusate viscosity improves speed by slowing dissipation of the concentration gradients. A flow switcher can also be used for bipolar temperature jumps with a rise time of approximately 100 microseconds.

Biophysical Phenomena↗