The connective tissue skeleton in the mammalian kidney and its innervation.

A special reticular basket-like system of connective tissue strips (called connective tissue skeleton - CTS) was found between the cortex and medulla in the kidney of various mammals. It enlarges the wall of the renal calyx (or pelvis) into the parenchyma. The main component of this system is collagen. A small amount of smooth muscle cells was found in one part of CTS srips situated around the papilla (the levator fornicis muscle). A dense monoaminergic and scanty cholinergic innervation was found in the whole system of the CTS. The functional importance of this system is discussed: (i) a tightly linked connection between the urine-discharging system and the kidney, (ii) 'milking' and similar effects in the papilla as well as perception of intrapelvic and intrarenal pressure, (iii) penetration of infection into the kidney and (iv) liberation of the monoaminergic transmitter.     

Impulse activity of the nodose ganglion neurons in myocardial ischemia

Standard microelectrode techniques were used to study the impulse activity of different types of nodosal ganglion neurons in the course of the development of myocardial ischemia. The cardiopulmonary late inspiratory and inspiratory-expiratory neuronal responses were estimated upon ligation of the coronary artery during the first respiratory cycle after blood flow stoppage. Spontaneous activity of cardiopulmonary neurons was not dependent on coronary circulation disturbances at the moment of coronary artery ligation. Later on, however, during the development of myocardial ischemia, there occurred substantial changes in all the types of nodosal ganglion neuronal activity, excluding real inspiratory neurons.     

NADPH-diaphorase activity in the nodose ganglion of normal and vagotomized guinea-pigs

The activity and distribution of reduced nico-tinamide adenine dinucleotide phosphate diaphorase (NADPH-diaphorase) in the nodose ganglion of normal and vagotomized guinea-pigs were examined by light and electron microscopy. Light microscopy confirmed a remarkable increase in the number of NADPH-diaphorase-reactive neurons in the nodose ganglion following unilateral cervical vagotomy. The increase was present at 5 days but became more prominent at 10 days and was sustained until at least 30 days after vagotomy when compared with the non-lesioned side. The NADPH-diaphorase reaction product was associated with the membrane of the rough endoplasmic reticulum, Golgi apparatus, mitochondria and nucleus of the nodose neurons. In animals killed 5 days post-operation, there was no noticeable degeneration in the nodose neurons. However, at 10 days, the mitochondria in some neurons appeared swollen and vacuolated with disrupted cristae. These changes were accentuated in some nodose neurons 20 and 30 days after vagotomy but there was no evidence of cell death. All the degenerating neurons exhibited NADPH-diaphorase activity. The increase in NADPH-diaphorase activity in the neuronal somata after vagotomy suggests that the enzyme is involved in either the retrograde degeneration or the recovery of the lesioned neurons. Received: 15 June 1995 / Accepted: 15 February 1996     

Fine structure of the epineural connective tissue sheath of the subesophageal ganglion in Helix aspersa

Summary The epineural connective tissue sheath investing the subesophageal ganglion of Helix aspersa consists of a superficial region and a deeper region. The superficial region contains masses of globular cells intermingled with smooth muscle cells and nerve fibers all embedded in a connective tissue matrix. The histochemical and fine structural features of the globular cells show seasonal changes. During autumn to winter glycogen accumulates in their cytoplasm; this accumulation is accompanied by the appearance of dense, cytoplasmic globules which fuse together and ultimately form large pools of granular material. All the organelles and cytoplasm are displaced towards the cell periphery. Various cell-membrane invaginations containing dense material are prominent but there is no direct evidence to link these structures with the uptake of metabolites for glycogenesis. In winter there is a concentration of homogeneous, membrane-bound inclusions in the vicinity of the Golgi bodies. It is suggested that these inclusions constitute a lipid store. They decrease in number during summer. The globular cells do not bear any intimate relation to neurons and there is no reason to include these cells in the neuroglia. The muscle cells often weave around the globular cells but there is no direct contact. Nerve fibers innervate at least some of the muscle cells. The connective tissue consists of large and small diameter fibers suggesting that maturation of the fibrous components of the intercellular matrix is taking place in the superficial regions of the epineural sheath.This work has been supported by the Australian Research Grants Committee.     

125I]-galanin binding sites in the human nodose ganglion

The cell bodies of centrally-projecting vagal afferent neurons are contained in the inferior vagal (nodose) ganglion. Although binding sites for a number of different neuropeptides/modulators have been detected in the human nodose ganglion, the presence of galanin binding sites has not been reported. In vitro receptor autoradiography using [125I]-galanin enabled visualisation of binding sites for galanin in the human nodose ganglion. The presence of such binding sites suggests a potential role for galanin in the neuromodulation of vagal transmission in humans.     

The effect of PKC activity on the TTX-R sodium currents from rat nodose ganglion neurons

To determine how protein kinase C (PKC) activity influences properties of the tetrodotoxin-resistant sodium current (TTX-R I(Na)) in neonatal rat nodose ganglion (NG) neurons, we assessed the effects of phorbol,-12-myristate,13-acetate (PMA), one of the PKC activators, and staurosporine, one of the PKC inhibitors, on the current. PMA (30 and 100 nM) induced an increase in the peak current amplitude of normalized current-voltage curves, a leftward shift in the potential for half activation (V(1/2)) of normalized conductance-voltage curves and a leftward shift of V(1/2) potential for steady-state inactivation curves. The effects of staurosporine (0.1 and 1 muM) on the peak current amplitude and the V(1/2) potential for activation were opposite compared with those seen after PMA application. Staurosporine (1 muM) antagonized PMA (100 nM)-induced modification of TTX-R I(Na). These results suggest that the basal TTX-R I(Na) obtained from neonatal NG neurons is controlled by the level of PKC activity.     

Chemotransduction properties of nodose ganglion cardiac afferent neurons in guinea pigs

To determine the chemotransduction characteristics of ventricular sensory neurites associated with nodose ganglion afferent neurons, various chemicals were applied individually to epicardial sensory neurites associated with individual afferent neurons in anesthetized guinea pigs. The following ion channel-modifying agents were tested: barium chloride, cadmium chloride, calcium chloride, the chelating agent EGTA, nickel chloride, potassium chloride, tetraethylammonium chloride, and veratridine. An acidic solution (pH 6.0) and oxygen-derived free radicals (H(2)O(2)) were tested. The following chemicals were also tested: adenosine, alpha- and beta-adrenergic agonists, angiotensin II, bradykinin, calcitonin gene-related peptide (CGRP), histamine, nicotine, the nitric oxide donor nitroprusside, substance P, and vasoactive intestinal peptide. A total of 102 cardiac afferent neurons was identified, of which approximately 66% were sensitive to mechanical stimuli applied to their epicardial sensory fields. Application of individual ion channel-modifying agents to epicardial sensory fields modified most associated afferent neurons, with barium chloride affecting each neuron studied. Ventricular sensory neurites associated with most identified neurons were also responsive to the other tested chemicals, with hydrogen peroxide, adenosine, angiotensin II, bradykinin, CGRP, clonidine, and nicotine inducing responses from at least 75% of the neurons studied. It is concluded that 1) the ventricular sensory neurites associated with nodose ganglion afferent neurons transduce a much wider variety of chemical stimuli than considered previously, 2) these sensory neurites employ a variety of membrane ion channels in their transduction processes in situ, and 3) adrenergic agents influence on sensory neurites associated with cardiac afferent neurons suggests the presence of a cardiac feedback mechanism involving local catecholamine release by adjacent sympathetic efferent postganglionic nerve terminals.     

Reaction of the nodose ganglion neurons to myocardial ischemia complicated by ventricular fibrillation

Standard microelectrode techniques were used to study the impulse activity of different types of nodosal ganglion neurons. Differences in electrical activity of cardiovascular neurons were observed in myocardial ischemia both complicated and not complicated by fibrillation. In these conditions rhythmic activity of cardiopulmonary, late inspiratory and inspiratory-expiratory neurons is quite similar.     

Desheathing the nodose ganglion is not a reliable method of de-efferentation in the ferret

The present study reports the results of physiological and anatomical experiments in which the purpose was to determine whether desheathing the nodose ganglion is a reliable method of vagal de-efferentation in the ferret. In physiological studies, the effects of electrically stimulating the treated and untreated vagal nerves on cardiovascular and intestinal responses were examined and compared with previously obtained data after left supranodose vagotomy. The anatomical studies illustrated the effects of desheathing the left nodose ganglion on the transport of horseradish peroxidase (HRP) within a thoracic vagal communicating branch. These data were compared to data from control animals and animals that had undergone left supranodose vagotomy. The results demonstrated that severing the fascicles overlying the left nodose ganglion and allowing the nerve fibers to degenerate, caused no reduction in labeled efferent cell bodies in the left dorsal motor nucleus of the vagus as compared to controls. However, after left supranodose vagotomy there were no efferent cell bodies labeled in the left dorsal motor nucleus of the vagus. Following degeneration of the fascicles, electrical stimulation of the peripheral cut end of this nerve did not abolish the efferent responses in 7 out of 9 animals studied, whereas supranodose vagotomy abolished the responses in all animals. These findings demonstrate that desheathing the nodose ganglion and thereby removing the nerve bundles overlying the nodose ganglion is not a guaranteed method of destroying the efferent fibers in the vagus nerve of the ferret. Supranodose vagotomy, therefore, is a more reliable method of de-efferentation in this species.