Date of Graduation

1998

Document Type

Thesis

Abstract

Guniea-pig inferior mesenteric ganglion (IMG) neurons that innervate artery or vein were separate neurons and there was no double labeling (Fluorogold and rhodamine beads) in the labeled neurons. The arterial neurons located in the central part of the IMG whereas venous neurons located peripherally. The cross-sectional area of total somata of arterial neurons was smaller than those of venous neurons which were smaller than unlabeled neurons. NPY-IR was found in 18% of arterial neurons, but not in venous neurons. All of the labeled vascular neurons fired tonically using whole cell patch-clamp recordings. All three types of neurons received a capsaicin-sensitive primary sensory innervation (50 to 75%) which contained immunoreactivity for calcitonin gene-related peptide (CGRP), neuronal nitric oxide synthase (NOS) and substance P (SP). CGRP and SP immunoreactivity was less dense around arterial and venous neurons compared to its density around unlabeled neurons. NOS positive innervation around venous neurons was denser than around artery neurons and all of it was of primary sensory origin. A nitric oxide (NO) donor, S-nitrosoacetylpenicillarnine (SNAP), induced a concentration- and voltage-dependent inwardly directed shift in holding current (inward current shift) in 89% of neurons tested on cultured dissociated guinea-pig celiac ganglion (CG) neurons. The inward current shift was sensitive to NO scavenger reduced hemoglobin, intra- or extra-cellular cesium and the extracellular potassium concentration. The SNAP-induced inward current shift was mediated by a decrease in calcium-dependent potassium currents diminished by apamin (100nM), charybdotoxin (10nM) or tetraethylammonium. (TEA; 5MM) and abolished by a combination of apamin and TEA. In the presence of extracellular cobalt, SNAP produced an outward current that was concentration- and voltage-dependent, sensitive to reduced hemoglobin and extracellular cesium, and was reduced by 4-aminopyridine (4-AP; 1mM). In the absence of cobalt, 4-AP increased the SNAP-induced inward current shift. The data indicate that IMG neurons Projecting to mesenteric blood vessels can be distinguished from one another by their location, by the soma cross-sectional area, by the distribution of NPY-IR, by their firing pattern, and by primary sensory innervation. NO inhibited the after hyperpolarization (AHP) and activated the delayed rectifier (IKV) of CG neurons.

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