Ultrasound-Guided Midpoint Transverse Process to Pleura Nerve Block for Medical Thoracoscopy: A Case Report.

We performed the midpoint transverse process to pleura (MTP) block in a patient with a recurrent pleural effusion requiring medical thoracoscopy, drainage of pleural effusion, talc poudrage, and placement of tunneled pleural catheter under sedation while in the left lateral decubitus position. Forty milliliters of a combination of bupivacaine hydrochloride and lidocaine, with dexamethasone and clonidine as adjuvants, was injected at the T6 level under ultrasound guidance with satisfactory intra- and postoperative analgesia.

Effects of Catheter Tip Location on the Spread of Sensory Block Caused by a Continuous Thoracic Paravertebral Block: A Prospective, Randomized, Controlled, Double-Blind Study.

Single injections in the anterior region of the thoracic paravertebral space (TPVS) have been reported to generate a multisegmental longitudinal spreading pattern more frequently than those in the posterior region of the TPVS. In this trial, we examined the hypothesis that a continuous thoracic paravertebral block (TPVB) administered through a catheter inserted into the anterior region of the TPVS allows a wider sensory block dispersion. Fifty consecutive patients undergoing video-assisted thoracic surgery were enrolled. Before the surgery, an infusion catheter was inserted into the TPVS through a needle placed adjacent to either the parietal pleura (group A) or internal intercostal membrane (group P) using an ultrasound-guided intercostal transverse approach according to a randomized allocation schedule. A chest radiograph was obtained postoperatively after injection of 10 mL of radiopaque dye through the catheter. Thereafter, 20 mL of 0.375% levobupivacaine was injected via the catheter, followed by commencement of continuous TPVB with 0.25% levobupivacaine at 8 mL/h. The primary outcome was the number of blocked dermatomes at 24 h after surgery. The secondary outcomes included radiopaque dye spreading patterns, the number of segments reached by the radiopaque dye, the number of blocked dermatomes at 2 h after surgery, and pain scores. The median (interquartile range [range]) number of blocked dermatomes 24 h after surgery was 3 (2.75-4 [1-6]) in group A (n = 22) and 2 (1.5-3 [0-7]) in group P (n = 25; p = 0.037). No significant differences in the other outcomes were found between the groups. In conclusion, a continuous TPVB administered using a catheter supposedly inserted into the anterior region of the TPVS allows a wider sensory block dispersion than a catheter inserted into the posterior region of the TPVS. This trial is registered with the UMIN Clinical Trials Registry (UMIN000018578).

Vagal nerve endings in visceral pleura and triangular ligaments of the rat lung.

The inner thoracic cavity is lined by the parietal pleura, and the lung lobes are covered by the visceral pleura. The parietal and visceral plurae form the pleural cavity that has negative pressure within to enable normal respiration. The lung tissues are bilaterally innervated by vagal and spinal nerves, including sensory and motor components. This complicated innervation pattern has made it difficult to discern the vagal vs. spinal processes in the pulmonary visceral pleura. With and without vagotomy, we identified vagal nerve fibres and endings distributed extensively in the visceral pleura ('P'-type nerve endings) and triangular ligaments ('L'-type nerve endings) by injecting wheat germ agglutinin-horseradish peroxidase as a tracer into the nucleus of solitary tract or nodose ganglion of male Sprague-Dawley rats. We found the hilar and non-hilar vagal pulmonary pleural innervation pathways. In the hilar pathway, vagal sub-branches enter the hilum and follow the pleural sheet to give off the terminal arborizations. In the non-hilar pathway, vagal sub-branches run caudally along the oesophagus and either directly enter the ventral-middle-mediastinal left lobe or follow the triangular ligaments to enter the left and inferior lobe. Both vagi innervate: (i) the superior, middle and accessory lobes on the ventral surfaces that face the heart; (ii) the dorsal-rostral superior lobe; (iii) the dorsal-caudal left lobe; and (iv) the left triangular ligament. Innervated only by the left vagus is: (i) the ventral-rostral and dorsal-rostral left lobe via the hilar pathway; (ii) the ventral-middle-mediastinal left lobe and the dorsal accessory lobe that face the left lobe via the non-hilar pathway; and (iii) the ventral-rostral inferior lobe that faces the heart. Innervated only by the right vagus, via the non-hilar pathway, is: (i) the inferior (ventral and dorsal) and left (ventral only) lobe in the area near the triangular ligament; (ii) the dorsal-middle-mediastinal left lobe; and (iii) the right triangular ligament. Other regions innervated with unknown vagal pathways include: (i) the middle lobe that faces the superior and inferior lobe; (ii) the rostral-mediastinal inferior lobe that faces the middle lobe; and (iii) the ventral accessory lobe that faces the diaphragm. Our study demonstrated that most areas that face the dorsal thoracic cavity have no vagal innervation, whereas the interlobar and heart-facing areas are bilaterally or unilaterally innervated with a left-rostral vs. right-caudal lateralized innervation pattern. This innervation pattern may account for the fact that the respiratory regulation in rats has a lateralized right-side dominant pattern.

Inhibitory responses in Aplysia pleural sensory neurons act to block excitability, transmitter release, and PKC Apl II activation.

Expression of the 5-HT(1Apl(a)) receptor in Aplysia pleural sensory neurons inhibited 5-HT-mediated translocation of the novel PKC Apl II in sensory neurons and prevented PKC-dependent synaptic facilitation at sensory to motoneuron synapses (Nagakura et al. 2010). We now demonstrate that the ability of inhibitory receptors to block PKC activation is a general feature of inhibitory receptors and is found after expression of the 5-HT(1Apl(b)) receptor and with activation of endogenous dopamine and FMRFamide receptors in sensory neurons. Pleural sensory neurons are heterogeneous for their inhibitory response to endogenous transmitters, with dopamine being the most prevalent, followed by FMRFamide, and only a small number of neurons with inhibitory responses to 5-HT. The inhibitory response is dominant, reduces membrane excitability and synaptic efficacy, and can reverse 5-HT facilitation at both naive and depressed synapses. Indeed, dopamine can reverse PKC translocation during the continued application of 5-HT. Reversal of translocation can also be seen after translocation mediated by an analog of diacylglycerol, suggesting inhibition is not through blockade of diacylglycerol production. The effects of inhibition on PKC translocation can be rescued by phosphatidic acid, consistent with the inhibitory response involving a reduction or block of production of this lipid. However, phosphatidic acid could not recover PKC-dependent synaptic facilitation due to an additional inhibitory effect on the non-L-type calcium flux linked to synaptic transmission. In summary, we find a novel mechanism downstream of inhibitory receptors linked to inhibition of PKC activation in Aplysia sensory neurons.

Novel insights in the neurochemistry and function of pulmonary sensory receptors.

Afferent nerves in the airways and lungs contribute to optimisation of the breathing pattern, by providing local pulmonary information to the central nervous system. Airway sensory nerve terminals are consequently tailored to detect changes readily in the physical and chemical environment, thereby leading to a variety of respiratory sensations and reflex responses. Most intrapulmonary nerve terminals arise from fibres travelling in the vagal nerve, allowing a classification of "sensory airway receptors", based on their electrophysiologically registered action potential characteristics. Nowadays, at least six subtypes of electrophysiologically characterised vagal sensory airway receptors have been described, including the classical slowly and rapidly adapting (stretch) receptors and C-fibre receptors. The architecture of airways and lungs makes it, however, almost impossible to locate functionally the exact nerve terminals that are responsible for transduction of a particular intrapulmonary stimulus. With the advances in immunohistochemistry in combination with confocal microscopy, airway sensory receptor end organs can now be examined and evaluated objectively. Based on their "neurochemical coding", morphology, location and origin, three sensory receptor end organs are currently morphologically well characterised: smooth muscle-associated airway receptors (SMARs), neuroepithelial bodies (NEBs) and visceral pleura receptors (VPRs). The present information on the functional, morphological and neurochemical characteristics of these sensory receptors leads to important conclusions about their (possible) function. Currently, ex vivo lung models are developed that allow the selective visualisation of SMARs, NEBs and VPRs by vital staining. The described ex vivo models will certainly facilitate direct physiological studies of the morphologically and neurochemically identified airway receptors, thereby linking morphology to physiology by identifying in situ functional properties of a given receptor end organ.

Anatomy of the pleura.

The pleura is a monolayer of mesothelial cells covering the lung and inner surface of the chest cavity, creating the pleural space. The mesothelial cells rest on a matrix of collagen, elastic fibers, blood vessels, and lymphatics, which allow the lung and chest to expand and contract, protected from friction by the pleural fluid and properties of the mesothelial cells. With a rich blood supply and lymphatic system just deep to the mesothelial layer, the pleura is a dynamic layer protecting the lung and pleural cavity from infection while transmitting the forces of respiration without damage to the underlying lung parenchyma.

Cervical incision thoracic endoscopic surgery: a minimally invasive endoscopic approach in thoracic surgery.

Cervical incision thoracic surgery has recently been described. Currently, there is a move to increase the role of flexible endoscopy in surgery. The use of a flexible endoscope through a natural orifice into the thoracic cavity still remains ethically doubtful. The authors present a surgical experimental study using a flexible endoscope through a cervical incision for the exploration of both the mediastinum and the thoracic cavity in a cadaver. An experimental work on 10 refrigerated and non-embalmed cadavers was initiated. We used a unique device - a standard double-channel flexible video gastroscope. Through a small cervical incision, we performed simultaneous exploration of the mediastinum and both pleural cavities. Identification and biopsies of mediastinal lymph nodes at levels 2R, 4R, 7 and 4L were easy to perform in all subjects. In eight cadavers, we performed an assessment of bilateral pleural cavities and multiple pleural biopsies as well as bilateral thoracic sympathectomy. A chest tube was placed in the thoracic cavity at the end of all pleural procedures. The potential advantages of this approach are simultaneous exploration of the mediastinum and pleura and the performance of several thoracic interventions through a small cervical incision. The flexible endoscope could become a surgical tool for thoracic surgery.

The contribution of the pleural type 12 interneuron to swim acceleration in Clione limacina.

The pteropod mollusc, Clione limacina, swims by alternate dorsal-ventral flapping movements of its wing-like parapodia. The basic swim rhythm is produced by a network of pedal swim interneurons that comprise a swim central pattern generator (CPG). Serotonergic modulation of both intrinsic cellular properties of the swim interneurons and network properties contribute to swim acceleration, the latter including recruitment of type 12 interneurons into the CPG. Here we address the role of the type 12 interneurons in swim acceleration. A single type 12 interneuron is found in each of the pleural ganglia, which contributes to fast swimming by exciting the dorsal swim interneurons while simultaneously inhibiting the ventral swim interneurons. Each type 12 interneuron sends a single process through the pleural-pedal connective that branches in both ipsilateral and contralateral pedal ganglia. This anatomical arrangement allowed us to manipulate the influence of the type 12 interneurons on the swim circuitry by cutting the pleural-pedal connective followed by a "culture" period of 48 h. The mean swim frequency of cut preparations was reduced by 19% when compared to the swim frequency of uncut preparations when stimulated with 10(-6) M serotonin; however, this decrease was not statistically significant. Additional evidence suggests that the type 12 interneurons may produce a short-term, immediate effect on swim acceleration while slower, modulatory inputs are taking shape.

Evidence of innervation in talc-induced pleural adhesions.

STUDY OBJECTIVES: To conduct a detailed morphologic and ultrastructural study of pleural adhesions following talc pleurodesis. METHODS: Talc with a main particle size of 8.36 +/- 0.2 mum (mean +/- SEM) and at a dose of 200 mg/kg in a 2-mL slurry was instilled via a small catheter into the pleural cavity of 10 male rabbits. Five rabbits were killed at 1 week, and five rabbits were killed at 1 month after instillation. At autopsy, after macroscopically observing the pleural cavity, adhesions were excised from opposing pleural surfaces and processed for histopathologic, immunocytochemical, and ultrastructural study. RESULTS: At 1 week, all adhesions examined were mesothelium-covered fibrovascular bands containing well-developed blood and lymphatic vessels establishing a structural continuity between both pleural layers. Nerves were present in adhesions from 20% of the rabbits. They consisted of a single fascicle containing 5 to 20 thin myelinated axons of various diameters (1 to 6 microm) uniformly distributed throughout the nerve section. The anatomic location of the adhesion did not appear to influence its overall morphology. CONCLUSIONS: As early as at 1 week, adhesions are well-formed structures more resembling newly formed pleural tissue than a simple scar. Nerve fibers in pleural adhesions are reported for the first time, which suggests that these adhesions are potentially capable of conducting pain stimuli. Further studies are required in order to confirm our results in human pleural adhesions.

Spinal afferent neurons projecting to the rat lung and pleura express acid sensitive channels.

BACKGROUND: The acid sensitive ion channels TRPV1 (transient receptor potential vanilloid receptor-1) and ASIC3 (acid sensing ion channel-3) respond to tissue acidification in the range that occurs during painful conditions such as inflammation and ischemia. Here, we investigated to which extent they are expressed by rat dorsal root ganglion neurons projecting to lung and pleura, respectively. METHODS: The tracer DiI was either injected into the left lung or applied to the costal pleura. Retrogradely labelled dorsal root ganglion neurons were subjected to triple-labelling immunohistochemistry using antisera against TRPV1, ASIC3 and neurofilament 68 (marker for myelinated neurons), and their soma diameter was measured. RESULTS: Whereas 22% of pulmonary spinal afferents contained neither channel-immunoreactivity, at least one is expressed by 97% of pleural afferents. TRPV1+/ASIC3- neurons with probably slow conduction velocity (small soma, neurofilament 68-negative) were significantly more frequent among pleural (35%) than pulmonary afferents (20%). TRPV1+/ASIC3+ neurons amounted to 14 and 10% respectively. TRPV1-/ASIC3+ neurons made up between 44% (lung) and 48% (pleura) of neurons, and half of them presumably conducted in the A-fibre range (larger soma, neurofilament 68-positive). CONCLUSION: Rat pleural and pulmonary spinal afferents express at least two different acid-sensitive channels that make them suitable to monitor tissue acidification. Patterns of co-expression and structural markers define neuronal subgroups that can be inferred to subserve different functions and may initiate specific reflex responses. The higher prevalence of TRPV1+/ASIC3- neurons among pleural afferents probably reflects the high sensitivity of the parietal pleura to painful stimuli.

Respiratory and circulatory effects of parietal pleural afferent stimulation in rabbits.

Respiratory symptoms accompanying pleural diseases combine dyspnea, tachypnea, rapid shallow breathing, and sometimes hypotension. There are no experimental data on the changes in respiratory and circulatory functions elicited by the activation of pleural afferents. After removal of all muscles covering the 5th to 10th intercostal spaces, we investigated in paralyzed, vagotomized rabbits the changes in phrenic discharge, transpulmonary pressure, and systemic arterial pressure in response to an outwardly directed force exerted on the parietal pleura or the local application of solutions containing lactic acid or inflammatory mediators. Mechanical stimulation of the pleura induced an immediate decrease in both integrated phrenic discharge and arterial blood pressure, the responses being positively correlated with the magnitude of force applied on the pleura. No accompanying changes in ventilatory timing, transpulmonary pressure, or heart rate were measured. Lactic acid solution also elicited an inhibition of phrenic activity and a fall in blood pressure. Section of the internal intercostal nerves supplying the stimulated intercostal spaces totally abolished the responses to mechanical stimulation or lactic acid. An inflammatory mixture elicited only modest respiratory and circulatory effects. We concluded that an acute mechanical distension of the parietal pleura as well as its chemical stimulation by lactic acid elicit a marked inhibition of phrenic motoneurons combined to a reduction of the sympathetic outflow to the circulatory system.

Identification and properties of parietal pleural afferents in rabbits.

Although pain and dyspnoea are common symptoms in pleural diseases, there are few studies on the sensory innervation of the pleura. Using rabbits, after removal of all muscles in the intercostal space to be studied, we investigated the afferents of the internal intercostal nerve by applying to the internal thoracic wall pieces of gauze soaked in warmed (37 degrees C), buffered saline (mechanical stimulation) or solutions containing lactic acid, inflammatory mediators or capsaicin (chemical stimulation). The afferent conduction velocity ranged from 0.5 to 14 m s(-1). Most units (97%) were activated by mechanical stimulation of the pleura (local positive pressure range = 4.5-8.5 cmH2O) and we found a linear relationship between the discharge rate of afferents and the force applied to the thoracic wall. The majority of mechanosensitive units (70%) also responded to one or several chemical agents. Thus, the afferents were activated by lactic acid (49%) and/or a mixture of inflammatory mediators (50%). Local application of capsaicin elicited an initial increased or decreased background afferent activity in 57% of the afferents, a delayed decrease in firing rate being noted in some units initially activated by capsaicin. Capsaicin blocked the afferent response to a further application of inflammatory mediators but did not affect the mechanosensitive units. Thus, sensory endings connected with thin myelinated and unmyelinated fibres in the internal intercostal nerve detect the mechanical and chemical events of pleural diseases.

AMRP peptides modulate a novel K(+) current in pleural sensory neurons of Aplysia.

Modulation of Aplysia mechanosensory neurons is thought to underlie plasticity of defensive behaviors that are mediated by these neurons. In the past, identification of modulators that act on the sensory neurons and characterization of their actions has been instrumental in providing insight into the functional role of the sensory neurons in the defensive behaviors. Motivated by this precedent and a recent report of the presence of Aplysia Mytilus inhibitory peptide-related (AMRP) neuropeptides in the neuropile and neurons of the pleural ganglia, we sought to determine whether and how pleural sensory neurons respond to the AMRPs. In cultured pleural sensory neurons under voltage clamp, AMRPs elicited a relatively rapidly developing, then partially desensitizing, outward current. The current exhibited outward rectification; in normal 10 mM K(+), it was outward at membrane potentials more positive than -80 mV but disappeared without reversing at more negative potentials. When external K(+) was elevated to 100 mM, the AMRP-elicited current reversed around -25 mV; the shift in reversal potential was as expected for a current carried primarily by K(+). In the high-K(+) solution, the reversed current began to decrease at potentials more negative than -60 mV, creating a region of negative slope resistance in the I-V relationship. The AMRP-elicited K(+) current was blocked by extremely low concentrations of 4-aminopyridine (4-AP; IC(50) = 1.7 x 10(-7) M) but was not very sensitive to TEA. In cell-attached patches, AMRPs applied outside the patch-thus presumably through a diffusible messenger-increased the activity of a K(+) channel that very likely underlies the macroscopic current. The single-channel current exhibited outward rectification, and the open probability of the channel decreased with hyperpolarization; together, these two factors accounted for the outward rectification of the macroscopic current. Submicromolar 4-AP included in the patch pipette blocked the channel by reducing its open probability without altering the single-channel current. Based on the characteristics of the AMRP-modulated K(+) current, we conclude that it is a novel current that has not been previously described in Aplysia mechanosensory neurons. In addition to this current, two other AMRP-elicited currents, a slow, 4-AP-resistant outward current and a Na(+)-dependent inward current, were occasionally observed in the cultured sensory neurons. Responses consistent with all three currents were observed in sensory neurons in situ in intact pleural ganglia.

Role of kinins and sensory neurons in the rat pleural leukocyte migration induced by Phoneutria nigriventer spider venom.

The leukocyte migration induced by Phoneutria nigriventer spider venom (PNV) has been investigated in rats using the pleurisy model. Intrapleural injection of PNV (10-100 microg/cavity) caused a dose- and time-dependent leukocyte accumulation. The bradykinin B(2) receptor antagonist Hoe 140 (0.5 mg/kg) substantially inhibited PNV-induced cell accumulation, whereas the angiotensin-converting enzyme inhibitor captopril (2 mg/kg) potentiated by 80% this effect. The non-specific kallikrein inhibitor aprotinin and the plasma kallikrein inhibitor soybean trypsin inhibitor greatly reduced PNV-induced leukocyte migration, whereas the selective tissue kallikrein inhibitor P(ac)-F-S-R-EDDnp failed to affect PNV-induced responses. Treatment of rats with capsaicin (50 mg/kg) at the neonatal stage resulted in 67% inhibition of the PNV-induced cell migration. The neurokinin NK(1) receptor antagonist SR140333, but not the NK(2) receptor antagonist SR48968, reduced by 55% venom-induced cell accumulation. We conclude that bradykinin generation is involved in the PNV-induced pleural leukocyte migration in rats, where it can directly activate sensory nerves contributing to a neurogenic inflammatory mechanism.

Distribution and developmental changes in GABA-like immunoreactive neurons in the central nervous system of pond snail, Lymnaea stagnalis.

We examined three-dimensionally the arrangement of gamma-aminobutyric acid (GABA)-like immunoreactive neurons in the central nervous system (CNS) of the pond snail, Lymnaea stagnalis, by a combination of immunohistochemistry and confocal laser scanning microscopy on whole-mount preparations. GABA-like immunoreactivity was detected in all ganglia of the adult CNS. The following distribution of immunoreactive cell bodies was noted in the adult snail. Buccal ganglia: one cell body and five pairs of cell bodies, cerebral ganglia: one pair of cell bodies, pedal ganglia: two single cell bodies, two pairs of cell bodies, and three pairs of cell clusters, and pleural ganglia: one pair of cell bodies. In the asymmetrical parietal ganglia, three cell bodies were located in the left parietal ganglion; three cell bodies and three cell clusters were located in the right parietal ganglion. In the single visceral ganglion, a few scattered individual cell bodies and a cell cluster were GABA-like immunoreactive. Our results showed that the occurrence of GABA is widely spread in the CNS of adult L. stagnalis. GABA-like immunoreactivity in the CNS was not detected in the embryo but was observed after hatching, although the number of stained cells was less than in the adult, with the exception of those in the cerebral ganglia where their number decreased with maturation. Our results provide detailed maps of the central GABA-like immunoreactive neurons in juveniles, immatures, and adults of L. stagnalis.

Thoracoscopic splanchnicectomy: pilot evaluation of a simple alternative for chronic pancreatic pain control.

Achieving adequate pain control in patients with chronic pancreatitis remains a surgical challenge. The quest for a procedure that retains all of the residual pancreatic tissue in the absence of ductal dilatation remains elusive. This study sought to evaluate the feasibility and efficacy of thoracoscopic splanchnicectomy and attempted to outline the surgical anatomy appropriate to an adequate denervation. Of 17 patients considered suitable for the procedure, 16 had a sucessful outcome, which was statistically significant (p < 0.001). The longest follow-up of 30 months suggests that the procedure may be more enduring than percutaneous procedures. However, the surgical anatomy is not predictable owing to the racemose arrangement of the splanchnic fibers, and a long pleurotomy with transection of all medial fibers is necessary to effect denervation. Thoracoscopic splanchnicectomy may effect immediate pain relief with negligible morbidity and absent mortality. Although the follow-up period is short, the patient with the longest follow-up remains pain-free at 30 months. This procedure warrants scrutiny for its role in long-term pancreatic pain control.

Nerve fibers--mast cells correlation in the rat parietal pleura.

Our results show that a morphological correlation exists between catecholaminergic nerve fibers and mast cells in the rat parietal pleura. Mast cells are found in proximity to catecholaminergic nerve fibers. Moreover we have demonstrated that mast cells and nerve fibers in the perivascular areas of rat parietal pleura show the same formaldehyde fluorescence. In rats previously sympathectomized with neurotoxin 6-OHDA the nerve fibers appear disarranged and poorly fluorescent and related mast cells show a low fluorescence. The importance of this correlation and the possible role of mast cells are discussed.

Identification of specific mRNAs affected by treatments producing long-term facilitation in Aplysia.

Neural correlates of long-term sensitization of defensive withdrawal reflexes in Aplysia occur in sensory neurons in the pleural ganglia and can be mimicked by exposure of these neurons to serotonin (5-HT). Studies using inhibitors indicate that transcription is necessary for production of long-term facilitation by 5-HT. Several mRNAs that change in response to 5-HT have been identified, but the molecular events responsible for long-term facilitation have not yet been fully described. To detect additional changes in mRNAs, we investigated the effects of 5-HT (1.5 hr) on levels of mRNA in pleural-pedal ganglia using in vitro translation. Four mRNAs were affected by 5-HT, three of which were identified as calmodulin (CaM), phosphoglycerate kinase (PGK), and a novel gene product (protein 3). Using RNase protection assays, we found that 5-HT increased all three mRNAs in the pleural sensory neurons. CaM and protein 3 mRNAs were also increased in the sensory neurons by sensitization training. Furthermore, stimulation of peripheral nerves of pleural-pedal ganglia, an in vitro analog of sensitization training, increased the incorporation of labeled amino acids into CaM, PGK, and protein 3. These results indicate that increases in CaM, PGK, and protein 3 are part of the early response of sensory neurons to stimuli that produce long-term facilitation, and that CaM and protein 3 could have a role in the generation of long-term sensitization.

[The monoaminergic innervation of the mediastinal pleura in human fetuses]. / Monoaminergicheskaia innervatsiia mediastinal'noi plevry plodov cheloveka.

Mediastinal pleura was studied in pregnancy second part abortive human fetuses using histological and histochemical technique. It was found to have a well-developed monoaminergic apparatus that includes adrenergic axons and mast cells. Electron microscope study confirmed monoaminergic and single peptidergic vesicles presence in axons. Luminescent method revealed that mast cells of nerve plexuses and blood vessels contain catecholamines and indolalkylamines. Monoaminergic axons and mast cells were shown to constitute a functionally integrative apparatus that regulates local hemodynamics and trophics.

Receptive properties of primary afferent fibres from rabbit pleura, in vitro.

We investigated the physiological properties of mediastinal pleural primary afferent units by recording single nerve fibre activity from the phrenic nerve in an in vitro preparation of rabbit tissue. A total of 41 units with conduction velocities in the group III and IV range were examined for their responsiveness to mechanical, thermal and chemical stimuli. Most receptive fields were adjacent to the phrenic nerve-pericardiacophrenic artery complex. The thresholds to punctate mechanical stimulation (von Frey hairs) were widely scattered around a median of 5.4 mN; all fibres showed slowly adapting responses to mechanical stimulation. Heat sensitivity was observed in 7/41 units (17%), while 17/41 (41%) of the fibres exhibited a spurious transient excitation to strong and rapid cooling. Chemosensitivity was scarce with respect to capsaicin (7/33 (21%) of the units responding) but more common to CO2-saturated synthetic interstitial fluid (pH 6.1, 5/16 (31%) responding). The most effective stimulus was a mixture of bradykinin, serotonin, histamine and prostaglandin E2 ('inflammatory soup') which evoked stimulus responses in 27/33 (82%) of the afferent fibres challenged. Sensitization to mechanical stimuli occurred in 5/41 (12%) of the units, following the application of heat or inflammatory mediators. The rabbit pleura appears as a tissue mainly innervated by multimodal mechano- and chemosensitive afferent units.