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A microiontophoretic study on the nature of the putative synaptic neurotransmitter involved in the pedunculopontine-substantia nigra pars compacta excitatory pathway of the rat (1986)

Scarnati, E. ; Proia, A. ; Campana, E. ; [et al.]

Springer

Experimental brain research 62 (1986), S. 470-478

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ISSN: 1432-1106

Keywords: Pedunculopontine nucleus ; Substantia nigra pars compacta ; Excitatory responses ; Glutamate ; Acetylcholine

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary The nature of the synaptic transmitter involved in the excitatory fibers linking the nucleus tegmenti pedunculopontinus (PPN) to the pars compacta of the substantia nigra (SNPC) was investigated using microiontophoretic techniques in rats anesthetized with ketamine. Among the SNPC cells activated orthodromically by PPN electrical stimulation, only a few cells were weakly excited by iontophoretically administered acetylcholine (Ach) while most were not affected. Conversely all cells were promptly and powerfully excited by short pulses of glutamate (GLU). The administration of the GLU antagonists glutamic acid diethylester (GDEE) and D-α-aminoadipic acid (DAA) reversibly and simultaneously suppressed both the PPN-evoked orthodromic response and the GLU-induced excitation of SNPC cells without affecting their response to iontophoretic Ach. GDEE was more effective than DAA in counteracting the synaptically evoked excitation. On the other hand, atropine, while antagonizing the Ach response in those cells which were cholinoceptive, did not affect either the PPN-evoked or the GLU-induced excitation. Hence, despite the presence of cholinergic cells in the PPN region, Ach does not appear to be involved in the excitatory PPNSNPC pathway. The present findings suggest that the excitatory PPN fibers innervating the SNPC may utilize GLU or a closely related amino acid as a neurotransmitter.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00236025

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Viscous-inviscid coupling in free surface ship flows (1995)

Campana, E. ; Di Mascio, A. ; Esposito, P. G. ; [et al.]

Chichester : Wiley-Blackwell

International Journal for Numerical Methods in Fluids 21 (1995), S. 699-722

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ISSN: 0271-2091

Keywords: domain decomposition ; free-surface ; ship flow ; viscous flow ; Engineering ; Engineering General

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: An application of multidomain decomposition to the computation of the steady free surface flow past a ship hull is presented. Viscous effects are taken into account in the neighbourhood of solid walls and in the wake by the Reynolds averaged Navier-Stokes equations, whereas the assumption of irrotationality in the external flow allows a description by a potential model. Free surface boundary conditions have been implemented in a linearized form at the undisturbed waterplane. Suitable matching conditions are enforced at the interface between the viscous and the potential regions. The numerical results obtained for two merchant ship forms (the HSVA tanker and the Series 60 hull) are compared with experimental data available in the literature.

Additional Material: 23 Ill.