Neuroscience letters
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We studied the effects of bilateral vagotomy and step pulmonary inflations (5, 10, 15 mmHg, i.e., 0.66, 1.33, 2 kKPa) on sneeze reflex in ketamine-anaesthetized cats. Bilateral vagotomy lengthens the duration of preparatory inspiration and diminishes the amplitude of expiratory activities in sneeze. ⋯ At 10 mmHg pulmonary inflations, inspiration is inhibited and only expiratory thrust occurs. At 15 mmHg pulmonary inflations, vagal afferent stimulations inhibit the sneeze.
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Neuroscience letters · Aug 1994
High extracellular GABA levels in hippocampus--as a mechanism of neuronal protection in cerebral ischemia in adrenalectomized gerbils.
Adrenalectomy protects the brain from delayed neuronal damage that occurs following transient forebrain ischemia in gerbils. Gamma-amino butyric acid (GABA) and GABA-mimetic drugs also have a neuro-protective effect. In this study we estimated the extracellular glutamate and GABA levels in the hippocampus during transient forebrain ischemia in adrenelectomized gerbils (n = 8) compared to controls (n = 6). ⋯ The pattern of glutamate release did not show any difference between adrenelectomized animals and controls. Adrenelectomized animals showed marked increase in GABA levels during ischemia and upto 30 min after ischemia (P = 0.0287, 2-way ANOVA for repeated measurements). The enhanced GABA release may be one of the possible mechanisms of neuronal protection against ischemia in adrenelectomized gerbils.
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Neuroscience letters · Aug 1994
omega-Conotoxin GVIA binds to and blocks rat neuromuscular junction.
The effect of omega-conotoxin GVIA, a specific blocker of N-type calcium channels, on the synaptic transmission at the mammalian neuromuscular junction is controversial. We have found that 125I-omega-conotoxin binds to rat tibialis muscle end-plate; that omega-conotoxin blocks the neuromuscular transmission both in vivo, in the sciatic nerve-tibialis anterior muscle, and in vitro in the isolated phrenic nerve-diaphragm preparation; and does not affect muscle nicotinic receptors. We conclude that in rat neuromuscular junctions N-type calcium channels are important for neurotransmitter secretion.
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Neuroscience letters · Jul 1994
Comparative StudyNeurons dissociated from neocortex fire with 'burst' and 'regular' trains of spikes.
Neurons acutely dissociated from neocortex slices of 14-16-day-old rats were patch-clamped in physiological conditions. Different pyramidal cells, spontaneously or in response to current steps, generate regular spiking and intrinsically bursting behaviour during long periods of time. We show that typical firing properties recorded in somatosensory neocortex slices are preserved in dissociated pyramidal neurons originating from the slices themselves, thus, providing a way for the related characterization of biophysical properties of currents in identified subtypes of pyramidal neurons.
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Neuroscience letters · Jun 1994
Potentiation by capsaicin of lidocaine's tonic impulse block in isolated rat sciatic nerve.
Compound action potentials (CAPs) of A- and C-fibers were recorded from isolated sciatic nerves of the rat to determine whether tonic block of impulse conduction induced by lidocaine was affected by low doses of capsaicin. Capsaicin alone (50 microM) did not change the CAPs of either A- or C-fibers. ⋯ Capsaicin's potentiating effects were partially reversed after 30 min of wash. These results suggest that capsaicin may be a useful agent for the potentiation of impulse blockade by lidocaine.