Electrolyte distribution in rabbit superior cervical ganglion

Abstract— Superior cervical ganglia of the rabbit were removed and analysed for Na⁺, K⁺, Ca²⁺, Mg²⁺ and Cl^?. The mean electrolyte content in μmole/g wet wt. was as follows: Na⁺, 64.7 ± 1.3; K⁺, 65.1 ± 2.7; Ca²⁺, 3.71 ± 0.28; Mg²⁺, 3.70 ± 0.50; and Cl^?, 50.15 ± 2.26. Water content was 0.76 ± 0.01 ml/g wet wt. Extracellular space was 0.37 ± 0.01 ml/g, and the vascular space 0.0238 ± 0.0002. The mean resting potential of the rabbit superior cervical ganglion was – 68.6 mv. After correction for extracellular electrolyte content, the potential differences, E_Na, E_K and E_cl, were estimated to be +33.6 mv, –96.9 mv and -41.1 mv, respectively, in the ganglia. Permeability coefficients for K⁺, Na⁺, and Cl^? were estimated to be 1:0.06:0.02. Replacement of sodium in physiological saline solution by lithium results in a displacement of 94 per cent of the sodium content of the ganglion and 69 per cent of the potassium after 30 min of equilibration.     

Convergence of preganglionic fibers on superior cervical ganglion neurons in the rabbit

Intracellular recording techniques were used to record electrical response from neurons of the rabbit (isolated) superior cervical ganglion to single stimuli applied to bundles of preganglionic fibers as well as tonic electrical neuronal activity in this ganglion during acute experiments in situ. A review of the findings obtained confirms that neurons of the ganglion receive preganglionic synaptic inputs of two types, the first of a single pattern, formed by a preganglionic fiber; excitatory action of the latter on ganglion units suffices to induce postsynaptic action potentials (AP I) and the second of a multiple pattern, formed by several preganglionic fibers with relatively faint excitatory action, capable of evoking postsynaptic action potentials (AP II) only when excited in unison. Interspike intervals for AP I and AP II in tonic neuronal activity conformed to a normal distribution and a random distribution pattern respectively.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 252–261, March–April, 1989.     

Spontaneous activity of the isolated rabbit superior cervical sympathetic ganglion

Investigation of spontaneous activity (mean amplitude of spikes 200–300 µV, frequency from 0.07 to 2.9 Hz) in the rabbit superior cervical sympathetic ganglion by the sucrose gap method showed that this activity was completely blocked by D-tubocurarine and hexamethonium; its frequency was increased in hypertonic solution, by an increase in the external potassium concentration, and by the addition of theophylline and ethanol. These observations suggest that the activity observed is due to spontaneous liberation of acetylcholine mediator from preganglionic nerve endings. However, addition of tetrodotoxin and an increase in the external calcium concentration to 10 mM block spontaneous activity in the ganglion. This suggests that the observed spontaneous activity consists of action potentials.     

Phosphoinositide metabolism in rat superior cervical ganglion, vagus and phrenic nerve: effects of electrical stimulation and various blocking agents

Abstract— Paired vagus nerves, phrenic nerves or superior cervical ganglia from rats were incubated at 37 C for various times in a simple salt solution containing glucose and ³²P_i. One of the pair was usually stimulated electrically for 30 or 60 min. Stimulation of vagus nerve for 30 min increased phosphate incorporation into all the phospholipids studied but the increase was significant only in the case of triphos-phoinositide and diphosphoinositide. This increase was not accompanied by increased labelling of the nucleotide labile phosphate pool. Tetrodotoxin at concentrations sufficient to block transmission had no effect upon phospholipid labelling in vagus or phrenic nerve. Ouabain at blocking concentration did not affect polyphosphoinositide metabolism in vagus nerve but increased [³²P]labelling of the other phospholipids. Hemicholinium-3 increased the labelling of all three phosphoinositides in the sympathetic ganglia but the increase in phosphatidylinositol labelling due to electrical stimulation was not seen in the presence of this inhibitor.     

Pattern of tonic activity in different groups of rabbit superior cervical ganglion neurons

Tonic activity in rabbit superior cervical ganglion neurons was investigated using intracellular recording techniques as well as changes produced when the animal breathed a gaseous mix with a raised CO₂ level. The test neurons were divided into three groups depending on the pattern of their tonic activity and reflex change. Action potentials were produced by the activity of dominant and accessory preganglionic inputs in the firing pattern of all neuronal groups, implying the existence of other types of inputs into the neurons innervating different organs. Having analyzed changes in action potential rate and EPSP in the tonic activity of neurons from different groups, it was presumed that preganglionic fibers with a similar activity pattern converge on the majority of neurons in each group.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 665–672, September–October, 1987.     

Transmission pathways in the rat superior cervical ganglion

On isolated preparations of the superior cervical ganglion (SCG, n = 8) taken from 21-day-old rats, we studied the intraganglion pathways and mechanisms underlying generation of synaptic responses of SCG neurons to antidromic stimulation. One of the three nerves connected with the SCG was stimulated, and compound action potentials were recorded simultaneously from the other two nerves; then, the order of stimulated and recorded nerves was changed. Orthodromic stimulation of the cervical sympathetic nerve (CSN) evoked responses in the internal carotid nerve (ICN), which could be completely blocked by hexamethonium, and responses in the external carotid nerve (ECN), which contained a component that was not blocked by this of the ECN caused responses in the CSN, which were not blocked by hexamethonium. Effects of superfusion of the SCG with a Ca²⁺-free solution allowed us to conclude that the hexamethonium-insensitive component of the responses in the CSN and ECN and ECN-CSN conduction can be explained by the presence of direct fibers going from the CSN to the ECN with no synaptic relay. Possible mechanisms underlying antidromic stimulation-induced synaptic responses in SCG neurons are discussed. Neirofiziologiya/Neurophysiology, Vol. 39, Nos. 4/5, pp. 396–399, July–October, 2007.     

Phosphorylation of tyrosine hydroxylase in the superior cervical ganglion

We studied the phosphorylation of tyrosine hydroxylase in the superior cervical ganglion of the rat. Ganglia were preincubated with [³²P]P_i and were then incubated in non-radioactive medium containing a variety of agents that are known to activate tyrosine hydroxylase in this tissue. Tyrosine hydroxylase was isolated from homogenates of the ganglia by immunoprecipitation followed by polyacrylamide gel electrophoresis. ³²P-labelled tyrosine hydroxylase was visualized by radioautography, and the incorporation of ³²P into the enzyme was quantitated by densitometry of the autoradiograms. Veratridine produced a concentration-dependent increase in the incorporation of ³²P into tyrosine hydroxylase, with 50 μM veratridine producing a 5-fold increase in ³²P incorporation. The nicotinic agonist, dimethylphenylpiperazinium (100 μM), caused a 7-fold increase in the phosphorylation of tyrosine hydroxylase. The effect of dimethylphenylpiperazinium was maximal within 1 min and decreased upon continued exposure of the ganglia to this agent. The actions of dimethylphenylpiperazinium and of veratridine were dependent on extracellular Ca²⁺. Muscarine, 8-Br-cAMP, forskolin, vasoactive intestinal peptide, isoproterenol, deoxycholate and phospholipase C also stimulated the incorporation of ³²P into tyrosine hydroxylase. These data support the hypothesis that phosphorylation plays a role in activation of tyrosine hydroxylase produced by all of these agents.     

The neuronal electrical responses of the superior cervical ganglion in the rabbit to nociceptive skin stimulation]

The patterns of tonic activity in the neurons of rabbit superior cervical ganglion at rest and during noxious stimulation of the skin were studied using intracellular recording. According to reflex changes in the activity patterns, all neurons studied were classified into three groups. Cardiac rhythmicity is more pronounced in the neurons of the second type than in those of the first type. The magnitude of the cardiac rhythmicity in both types of neurons was reduced after noxious stimulation of the skin. In the third type of neurons the cardiac rhythmicity was absent. In some neurons slow excitatory and inhibitory postsynaptic potentials appeared resulting from skin stimulation.     

Granule-containing cells in the human superior cervical ganglion.

The fine structure of granule-containing cells in the human superior cervical ganglion is described. These cells are larger than the typical SIF cells in mammals and exhibit green-yellow fluorescence. They are characterized by numerous granular vesicles (80-140 nm in diameter) in the cytoplasm, but have many features in common with ordinary ganglion cells. They emit several long processes which form bundles together with ordinary nerve fibers. No synapses are found where the cells are presynaptic, although a few synapses are observed there where nerves are prosynaptic on the perikarya and processes of the cells. No close topographical relations are seen between the cells and blood vessels. It is suggested that the granule-containing cells are a special type of postganglionic aminergic neurons.     

Folate metabolism in the superior cervical ganglion histochemical study

Summary By means of histochemical methods, folic acid, dihydrofolate reductase and NADH₂-cytochrome-C-reductase were studied in the bovine superior cervical ganglion, in parallel with quantitative estimations of dihydrofolate reductase activity and in connection with the process of ageing. Various levels of folate metabolism were present in nerve cells and glial cells, as well as in pre or postganglionic nerves. In the process of ageing the activity of dihydrofolate reductase gradually decreased and the folic acid concentration in the nerve cells increased. Thus the enzyme — substrate ratio appeared to favour the enzyme in young animals but the substrate in old animals.     

Facilitation, augmentation, and potentiation of synaptic transmission at the superior cervical ganglion of the rabbit

The effect of repetitive stimulation on synaptic transmission was studied in the isolated superior cervical ganglion of the rabbit under conditions of reduced quantal content. Excitatory postsynaptic potentials (EPSP) were recorded with the sucrose gap technique to obtain estimates of transmitter release. Four components of increased transmitter release, with time constants of decay similar to those observed at the frog neuromuscular junction at 20 degrees C, were found in the ganglion at 34 degrees C: a first component of facilitation, which decayed with a time constant of 59 +/- 14 ms (mean +/- SD); a second component of facilitation, which decayed with a time constant of 388 +/- 97 ms; augmentation, which decayed with a time constant of 7.2 +/- 1 s; and potentiation, which decayed with a time constant of 88 +/- 25 s. The addition of 0.1-0.2 mM Ba2+ to the Locke solution increased the magnitude but not the time constant of decay of augmentation. Ba2+ had little effect on potentiation. The addition of 0.2-0.8 mM Sr2+ to the Locke solution appeared to increase the magnitude of the second component of facilitation. Sr2+ had little effect on augmentation or potentiation. These selective effects of Ba2+ and Sr2+ on the components of increased transmitter release in the rabbit ganglion are similar to the effects of these ions at the frog neuromuscular junction. Although the effects of Ba2+ and Sr2+ are similar in the two preparations, the magnitudes of augmentation and the second component of facilitation after a single impulse were about 6-10 times greater in the rabbit ganglion than at the frog neuromuscular junction. These results suggest that the underlying mechanisms in the nerve terminal that give rise to the components of increased transmitter release in the rabbit ganglion and frog neuromuscular junction are similar but not identical.     

Effects of synaptic Activity on the metabolism and release of purines in the rat superior cervical ganglion

The release of radioactive metabolites from isolated rat superior cervical ganglia was measured under various conditions following preloading with 3H-adenosine. The 3H label was recovered primarily in the adenosine metabolites, ATP, ADP, AMP, IMP, and inosine, rather than in adenosine itself. Increased release was evoked by preganglionic stimulation or by exposure to a high-K+ medium, whereas in a low-Ca2+-high-Mg2+ medium, both spontaneous release and evoked release of most metabolites were inhibited. Exposure of the ganglion to an atmosphere of N2 also increased the release of most labeled metabolites, but this release was not substantially affected by a low-Ca2+ medium. The fluorescent derivatives of the endogenous adenine-containing compounds present in the ganglion were prepared from homogenates and separated by high-performance liquid chromatography (HPLC). By the end of the testing period (6 hr), levels of ATP in the isolated ganglia had dropped to 10-20% of the initial values, while levels of ADP, AMP, and adenosine increased. There was little difference in these values between nonstimulated ganglia and those exposed to N2 or to a high-K+ medium.     

Effect of fixation in Carnoy's solution on nucleic acid and protein concentration in the rabbit superior cervical sympathetic ganglion]

By means of biochemical techniques, the stability of RNA, DNA and protein contents has been demonstrated in the rabbit superior cervical sympathetic node fixed in Carnoy's solution for 2 hours at 4 degrees C. A 2 hour fixation in Carnoy's fluid at room temperature, results, however, in a considerable loss of RNA (21%). The loss of DNA and protein did not exceed 2% of the total amount of the fresh ganglion tissue. Fixation at a higher temperature (37%) increased the loss percentage protein and of nucleic acids: 3.1, 5.5 and 42%, for protein, DNA and RNA, resp.     

Background activity of the rabbit superior cervical ganglion neurons: Soundness of random hypothesis of its formation

The soundness of hypotheses interpreting the mechanism of formation of background activity (BA) generated by the neurons of the rabbit superior cervical ganglion was analyzed, taking into account the statistical characteristics of this activity. These neurons are supplied with a multiple synapic input. According to the random hypothesis, the BA action potentials in the ganglion neurons result from occassional coincidence of the spikes arriving through independent presynaptic inputs. Our calculations showed that the frequency of BA action potentials observed in the experiments is too high to be explained by the random hypothesis and needs synchronization of firing in different presynaptic neurons, rather than their independent firing.Neirofiziologiya/Neurophysiology, Vol. 28, No. 1, pp. 47–52, January–February, 1996.