Parasympathetic Fibers Research Articles

Immunohistochemical study of the cavernous nerves in the periprostatic region

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The anatomy of the periprostatic tissues, in particular the fascial layers and neurovascular structures, remain a somewhat enigmatic and controversial area. Despite the considerable advances made in this area since the original dissections of Walsh and Donker almost thirty years ago, the precise location and function of these structures remains uncertain. The topic is of tremendous importance as we continue to refine surgical techniques to allow men the maximum opportunity to recover erectile function following radical prostatectomy. Yet many of these surgical refinements are not based on definitive knowledge of the relevant anatomy and clearly more knowledge is required. For the first time, we have not just characterized the quantitative nature of the periprostatic nerves, but we also offer some insight into the likely functional nature of these nerves by selectively staining the sympathetic and parasympathetic nerves using immunohistochemical methods. • To characterize the immunohistochemical nature of sympathetic and parasympathetic nerves surrounding the prostate. • Using serial sectioning, four male cadavers were investigated using a combination of haematoxylin and eosin staining and immunohistochemistry. Both the sympathetic and parasympathetic contributions to the autonomic nervous system in the periprostatic region were assessed by staining analysis, the number of nerves fibres was quantified, their position relative to the prostate recorded and their function inferred. • The fascial architecture of the neurovascular bundle (NVB) was also quantified. • Approximately 27.8% of all nerve fibres identified were found on the anterior half of the prostate, above the 3 to 9 o'clock level. At the base, mid, and apex of prostate, parasympathetic fibres accounted for 4%, 5% and 6.8% of the nerves located on the anterolateral aspect of the prostate, respectively. • Sympathetic nerves found above the 3 to 9 o'clock level represented ≈15% of the total number of nerves. • When staining the periprostatic fascia, the classical NVB exhibited a distinct fascial architecture with three separate compartments. • A tiny minority of nerves in the anterior periprostatic region are functionally significant parasympathetic nerves. • There is little anatomical evidence to support higher incisions in the lateral prostatic fascia to spare cavernous nerve fibres, although such approaches may reduce the risk of traction injury on the more posterolaterally located NVB. • The presence of distinct fascial compartments in the NVB is also confirmed.

Recuerdo y actualización de las bases anatómicas del pene

The knowledge of penile anatomy is basic to perform a proper diagnosis and direct the most adequate treatment of the various diseases that may appear: urethral stenosis, erectile dysfunction, congenital or acquired penile curvature, etc.; being its anatomical knowledge essential for a proper surgical management. The penis is the male organ involved in both voiding and sexual functions: the body of the penis is composed by three erectile bodies, (i.e the deep structures): the corpora cavernosa and the corpus spongiosum, this last surrounding and covering the urethra. Buck's fascia is in relation to the deep structures of the penis. The superficial fascia, dartos, is made up from a more areolar tissue and is in relation to skin and vessels. The vascularization of the deep structures comes from the common penile artery, a branch of the internal pudendal artery. Penile blood drains through three venous systems: superficial, intermediate and deep systems. Pudendal nerves are in charge of the sensitive and motor somatic innervations. Cavernosal nerves are a combination of parasympathetic and sympathetic afferent fibers, corresponding to the nerves of the autonomic system of the penis.

Ciliary ganglioplegic migraine: Migraine-related prolonged mydriasis

Transient, unilateral mydriasis has been reported in migraine patients, and this has been regarded as a possible co-morbidity between migraine and Adie's tonic pupil. Mydriasis that outlasts the duration of migraine attacks is rare. Through an eight-year period we have studied all patients referred to our neurological clinic because of migraine attack with mydriasis. All the patients underwent thorough neurologic and ophthalmologic examinations including MRI of the brain and testing of the pupil response to ocular instillation of dilute pilocarpine (0.125%). Seven women and two men, with a mean age of 33.8 ± 12.3 years (range: 19-52) were included. The patients presented during one hemicranial migraine attack with an ipsilateral mydriasis that persisted for a mean of three months, while migraine headaches remained with their typical episodic course. In all the patients a cholinergic supersensitivity in the symptomatic pupil was demonstrated, thus pointing to a dysfunction of the ipsilateral ganglionic parasympathetic fibers. Synchronous co-localization of the features suggests a pathogenic link between the pupil dysfunction and migraine, rather than a simultaneous coexistence of two independent disorders. Likely explanations include a latent Adie's pupil that could have been triggered during a particular migraine attack; a ciliar ganglionic lesion/dysfunction produced by the migrainous process; an ophthalmoplegic migraine with selective parasympathycoparesis; or an episodic ciliar ganglionitis with migrainous features. Ciliary ganglioplegic migraine is proposed as a nominal term pointing to the possible anatomic source of the migrainous-related pupil dysfunction; the pathogenesis remains unknown.

Experimental Physiology -Viewpoints: Parasympathetic control of blood flow to the activated human brain

Experimental Physiology -<i>Viewpoints</i>: Parasympathetic control of blood flow to the activated human brain

Evolution in the concept of erection anatomy

To review and to summarize the literature on anatomy and physiology of erection in the past three decades, especially the work done in our institution. A search of the PubMed database was performed using keywords erection, anatomy and erectile dysfunction (ED). Relevant articles were reviewed, analyzed and summarized. Penile vascularisation and innervation vary substantially. Internal pudendal artery is the major source of penile blood supply, but a supralevator accessory pudendal artery that may originate from inferior vesical or obturator or external iliac arteries is not uncommon. Section of this artery during radical prostatectomy (RP) may adversely affect postoperative potency. Anastomoses between the supra and the infralevator arterial pathways are frequent. The cavernous nerves (CNs) contain parasympathetic and sympathetic nerve fibers and these nerves lie within leaves of the lateral endopelvic fascia. Anastomoses between the CNs and the dorsal nerve of the penis are common. Nitric oxide released from noradrenergic, noncholinergic neurotransmission of the CN and from the endothelium is the principal neurotransmitter-mediating penile erection. Interactions between pro-erectile and anti-erectile neurotransmitters are not completely defined. Finally, medial preoptic area and paraventricular nucleus are the key structures in the central control of sexual function and penile erection. The surgical and functional anatomy of erection is complex. Precise knowledge of penile vascularisation and innervation facilitates treatment of ED especially after RP.

Quantitative analysis of parasympathetic innervation of the porcine heart

Parasympathetic control of the heart is an important component in the regulation of normal cardiac function. However, the anatomic course of parasympathetic innervation of the heart is unclear. The purpose of this study was to apply a gross parasympathetic nerve stain technique to reveal the details of the morphology of the cardiac parasympathetic nervous system. Ten whole pig hearts were stained using a histochemical method. Immediately after sacrifice, hearts were placed in a buffered solution containing acetylthiocholine, which precipitates with acetylcholinesterase, allowing identification of cholinergic nerves. The epicardial and endocardial surfaces of the atria and ventricles were examined for nerve thickness and density. In both atria, nerve density was significantly greater on the endocardium, but nerve thickness was significantly greater on the epicardium. The right atrium (RA) was more densely innervated than the left atrium (LA) on the endocardium, whereas the LA was more densely innervated than the RA on the epicardium. In the ventricles, numerous thick cholinergic nerves were clearly identifiable across the epicardium, generally running parallel to the left anterior descending artery. The endocardial surfaces of the ventricles revealed a dense network of fine parasympathetic nerve fibers. As in the atria, nerve density was greater on the ventricular endocardium, but nerve thickness was greater on the epicardium. The right ventricle (RV) was more densely innervated than the left ventricle (LV), whereas the LV endocardium was more densely innervated than the RV endocardium. The epicardial and endocardial surfaces of the atria and ventricles are richly innervated by parasympathetic nerves. The density of parasympathetic innervation is heterogeneous across both the epicardial and endocardial surfaces of the heart.

Frey’s syndrome - unusually long delayed clinical onset postparotidectomy: a case report

Frey's syndrome is a complication of parotidectomy that is thought to occur as a result of aberrant regeneration of the postganglionic parasympathetic nerve fibres supplying the parotid gland to severed postganglionic sympathetic fibres which innervate the sweat glands of the face. Frey's syndrome is difficult to treat but is a preventable phenomenon and surgeons must be aware of the available preventative methods during the initial surgery. An unusual case is presented involving a patient with delayed onset of Frey's syndrome 40 years after parotidectomy in childhood. The potential for this long-delayed clinical presentation should be discussed with the patient before surgery in the parotid gland. Diagnostic methods, preventive measures and management options are briefly discussed.

RETRACTED: Intrinsic innervation and dopaminergic markers after experimental denervation in rat thymus.

The aim of this study was to examine rat thymus innervation using denervation techniques and to explore the related microanatomical localization of dopamine, D1, D2 receptors and dopamine membrane transporter (DAT).In the thymus subcapsular region, the parenchymal cholinergic fibers belong exclusively to phrenic nerve branching. No somatic phrenic nerve branching was detected in any other analysed thymus lobule regions.In rats subjected to sympathetic or parasympathetic ablation, it was observed that catecholaminergic and cholinergic nerve fibers respectively contributed to forming plexuses along vessel walls.In the subcapsular and septal region, no parenchymal nerve branching, belonging to sympathetic or parasympathetic nervous system was noted. Instead, in the deep cortical region, cortico-medullary junction (CM-j) and medulla, catecholaminergic and cholinergic nerve fibers were detected along the vessels and parenchyma.Dopamine and dopamine receptors were widely diffused in the lobular cortico-medullary junction region and in the medulla, where the final steps of thymocyte maturation and their trafficking take place.No variation in dopamine and DAT immune reaction was observed following total or partial parasympathectomy or phrenic nerve cutting. After chemical or surgical sympathectomy however, neither dopamine nor DAT immune reaction was noted again. Instead, D1 and D2 dopamine receptor expression was not affected by thymus denervation.In rats subjected to specific denervation, it was observed the direct intraparenchymal branching of the phrenic nerve and sympathetic and parasympathetic fibers into thymus parenchyma along vessels. These findings on the dopaminergic system highlight the importance of neurotransmitter receptor expression in the homeostasis of neuroimmune modulation.

Cutting the chorda tympani: not just a matter of taste

Chorda tympani injury as a complication of middle-ear surgery has been extensively studied with regard to its effects upon taste. However, the chorda tympani also carries parasympathetic fibres to the salivary glands of the oral cavity. To date, little has been reported about the effect of chorda tympani section upon salivary function. Tertiary care centre. We report a case series of three patients with bilateral chorda tympani lesions. Chorda tympani function was assessed using 'taste strips' and unstimulated sialometry. A careful history of oral symptoms was taken. All patients showed transient or permanent bilateral ageusia of the anterior two-thirds of the tongue, and a decreased resting salivary flow rate. In addition, all patients suffered from transient or persistent, distressing xerostomia. Taste disorders may occur after middle-ear surgery but they are mostly transient, even when the chorda tympani nerves are sectioned bilaterally. In contrast, bilateral chorda tympani lesions may lead to severe, persistent and distressing xerostomia. Based on this neglected aspect of chorda tympani function, we emphasise the importance of preserving the chorda tympani whenever possible.

Surgical Anatomy of the Retroperitoneal Spaces, Part IV: Retroperitoneal Nerves

We present surgicoanatomical topographic relations of nerves and plexuses in the retroperitoneal space: 1) six named parietal nerves, branches of the lumbar plexus: iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, femoral. 2) The sacral plexus is formed by the lumbosacral trunk, ventral rami of S1-S3, and part of S4; the remainder of S4 joining the coccygeal plexus. From this plexus originate the superior gluteal nerve, which passes backward through the greater sciatic foramen above the piriformis muscle; the inferior gluteal nerve also courses through the greater sciatic foramen, but below the piriformis; 3) sympathetic trunks: right and left lumbar sympathetic trunks, which comprise four interconnected ganglia, and the pelvic chains; 4) greater, lesser, and least thoracic splanchnic nerves (sympathetic), which pass the diaphragm and join celiac ganglia; 5) four lumbar splanchnic nerves (sympathetic), which arise from lumbar sympathetic ganglia; 6) pelvic splanchnic nerves (nervi erigentes), providing parasympathetic innervation to the descending colon and pelvic splanchna; and 7) autonomic (prevertebral) plexuses, formed by the vagus nerves, splanchnic nerves, and ganglia (celiac, superior mesenteric, aorticorenal). They include sympathetic, parasympathetic, and sensory (mainly pain) fibers. The autonomic plexuses comprise named parts: aortic, superior mesenteric, inferior mesenteric, superior hypogastric, and inferior hypogastric (hypogastric nerves).

Non‐quantal release of acetylcholine from parasympathetic nerve terminals in the right atrium of rats

Acetylcholinesterase (AChE) inhibitors provoke typical cholinergic effects in the isolated right atrium of the rat due to the accumulation of acetylcholine (ACh). Our study was designed to show that in the absence of vagal impulse activity, ACh is released from the parasympathetic nerve fibres by means of non-quantal secretion. The conventional microelectrode technique was used to study changes in action potential (AP) configuration in the right atrium preparation of rats during application of AChE inhibitors. Staining with the lipophilic fluorescent dye FM1-43 was used to demonstrate the presence of endocytosis in cholinergic endings. The AChE inhibitors armin (10(7)-10(5)m) and neostigmine (10(7) to 5 x 10(6)m) caused a reduction of AP duration and prolonged the cycle length. These effects were abolished by atropine and were therefore mediated by ACh accumulated in the myocardium during AChE inhibition. Putative block of impulse activity of the postganglionic neurons by tetrodotoxin (5 x 10(7)m) and blockade of ganglionic transmission by hexomethonium (2 x 10(4)m), as well as blockade of all forms of quantal release with Clostridium botulinum type A toxin (50 U ml(1)), did not alter the effects of armin. Experiments with FM1-43 dye confirmed the effective block of exocytosis by botulinum toxin. Selective inhibition of the choline uptake system using hemicholinium III (10(5)m), which blocks non-quantal release at the neuromuscular junction, suppressed the effects of AChE inhibitors. Thus, accumulation of ACh is likely to be caused by non-quantal release from cholinergic terminals. We propose that non-quantal release of ACh, shown previously at the neuromuscular junction, is present in cholinergic postganglionic fibres of the rat heart in addition to quantal release.

Effects of autonomic nerve stimulation on colorectal motility in rats

Several disease processes of the colon and rectum, including constipation and incontinence, have been associated with abnormalities of the autonomic nervous system. However, the autonomic innervation to the colon and rectum are not fully understood. The aims of this study were to investigate the effect of stimulation of vagus nerves, pelvic nerves (PN) and hypogastric nerves (HGN) on colorectal motility in rats. Four strain gauge transducers were implanted on the proximal colon, mid colon, distal colon and rectum to record circular muscle contractions in rats. Electrical stimulation was administered to the efferent distal ends of the cervical vagus nerve, PN and HGN. Motility index (MI) was evaluated before and during stimulation. Electrical stimulation (5-20 Hz) of the cervical vagus elicited significant contractions in the mid colon and distal colon, whereas less pronounced contractions were observed in the proximal colon. Pelvic nerves stimulation elicited significant contractions in the rectum as well as the mid colon and distal colon. Atropine treatment almost completely abolished the contractions induced by vagus nerve and PN stimulation. Hypogastric nerves stimulation caused relaxations in the rectum, mid colon and distal colon. The relaxations in response to HGN stimulation were abolished by propranolol. Vagal innervation extends to the distal colon, while the PN has projections in the distribution of the rectum through the mid colon. This suggests a pattern of dual parasympathetic innervation in the left colon. Parasympathetic fibers regulate colorectal contractions via muscarinic receptors. The HGN mainly regulates colorectal relaxations via beta-adrenoceptors.

Distribution of the High-Affinity Binding Site and Intracellular Target of Botulinum Toxin Type A in the Human Bladder

BackgroundBotulinum toxin type A (BoNTA) has been successfully used in the treatment of refractory detrusor overactivity. The toxin is internalized after binding a high-affinity receptor, synaptic vesicle protein 2 (SV2), which is exposed in the cell membrane during the exocytosis process. In the cytoplasm, BoNTA cleaves specific sites of synaptosomal-associated protein 25 (SNAP-25), preventing the assembly of the synaptic fusion complex SNARE and blocking exocytosis. ObjectiveIn the present work, the distribution of SV2 and SNAP-25 was first investigated in human bladders. The neurochemistry of BoNTA-sensitive structures was then investigated using markers for parasympathetic, sympathetic, and sensory fibers. Design, setting, and participantsHuman bladders were obtained from cadaveric organ donors (age range: 19–74 yr). MeasurementsBladder sections were processed for single or dual immunofluorescence staining with antibodies against SV2, SNAP-25, β-3 tubulin, vesicular acetylcholine transporter, tyrosine hydroxilase, and calcitonin gene-related peptide. Results and limitationsSV2 and SNAP-25 immunoreactive fibers were distributed throughout the suburothelium and muscular layer. Double labeling showed extensive colocalization of both proteins in nerve fibers. SV2 is more expressed in parasympathetic fibers than in sympathetic or sensory fibers. No expression was found in urothelial or muscular cells. Because only normal bladders were used, this distribution should be applied with caution to pathologic bladders. ConclusionsSV2 and SNAP-25 colocalize abundantly throughout the urinary bladder. SV2 is more abundant in cholinergic, parasympathetic fibers. These nerves are suggested to be the main target for BoNTA action in the human urinary bladder.

Parasympathectomy induces morphological changes and alters gene-expression profiles in the rat submandibular gland

Objective The chorda-lingual (CL) nerve carries parasympathetic fibers to the hilum of the sublingual and submandibular glands (SMGs) and evokes the secretion of saliva. The effect of cutting the CL nerve on the biological processes in SMGs was investigated by examining the gene-expression profiles in the SMGs after a surgical parasympathectomy. Methods At day 3 after the CL nerve cut, the changes in the SMGs at both the experimental cut and contralateral control sides were analysed by microarray and light microscopy. The expression levels of 6 selected genes were confirmed by real-time PCR, Western blot and immunofluorescence staining. Results The wet weight of the parasympathectomised SMGs decreased significantly compared to that of the contralateral side ( p < 0.05). Histological analyses after the parasympathectomy showed a widened interacinar space as well as some atropic changes to the acini of the SMGs in the cut side. Microarray analysis revealed that twofold differential expression in mRNA expression in the parasympathectomized SMGs were detected in 88 genes (0.004%): 41 genes were overexpressed, 11 were underexpressed and 36 were unknown. Changes of the expression of 6 selected genes detected by Western blot and/or real-time PCR were consistent with the microarray data. Conclusion The important genes involved in biological processes for salivation were identified through a large-scale gene expression analysis.

Meibom-Drüsen

The Meibomian glands are large sebaceous glands that are located as separate gland strands in parallel arrangement within the tarsal plates of the eyelids. Their oily product (meibum) is secreted by a holocrine mechanism during which the secretory cells (meibocytes) are completely transformed into the meibum after synthesis and accumulation of lipids. After production in the gland acini, meibum is transported through the ductal system via the connecting duct (ductule) and the central duct towards the orifice at the free lid margin close to the inner lid border. The embryological development of the Meibomian glands takes place during the differentiation of the eyelids in the sealing phase of the eyelids. They are not directly associated with hair follicles but share important similarities in embryology, structure and keratinization potency with the cilia. Similar to the sebaceous glands Meibomian glands are regulated via sex hormones and androgens have a supporting function whereas estrogens act antagonistically. However, in contrast to other sebaceous glands they also have a distinct innervation, apart from sympathetic and sensory primarily by parasympathetic fibers that share the innervation pattern of the lacrimal glands. The anatomy, embryology and histology of the Meibomian glands are explained here, mainly with respect to humans, in an extensive review.

Parasympathetic vasodilator fibers in rat digastric muscle

The present study examined whether parasympathetic vasodilator fibers exist in rat jaw-opening muscles such as the digastric muscle. The mental nerve was stimulated to activate the parasympathetic vasodilator nerve in the digastric muscle. Electrical stimulation of the mental nerve elicited intensity- and frequency-dependent increases of blood flow in this muscle. These increases were markedly reduced by hexamethonium in dose- and time-dependent manners, but pretreatment with phentolamine or propranolol had no effect. Pretreatment with atropine also attenuated the increase in blood flow in digastric muscle. When retrograde fluorogold was injected into the digastric muscle, labeled neurons were observed in the otic ganglion only on the ipsilateral side, but not in the pterygopalatine ganglion of either side. These results indicate that parasympathetic vasodilator fibers originate from cell bodies in the otic ganglion in rat digastric muscle.

Effect of nitric oxide synthase inhibition and nerve stimulation frequency on autonomous choroidal vasodilation

Abstract Purpose To investigate the effect of non selective nitric oxide synthase inhibition and the influence of nerve stimulation frequencies on parasympathetic choroidal vasodilation. Methods Stimulations of parasympathetic nerve fibers of the greater petrosal nerve with 8 and 20 Hz were performed simultaneously with continuous measurements of intraocular pressure (IOP), choroidal blood flow (ChorBF), orbital venous pressure (OVP) and arterial pressure at the eye level (MAP). Stimulations were perfomed at baseline, after non selective inhibition of all nitric oxide synthases with L‐NAME and after systemic administration of atropine in an anesthetized acute rabbit model. Results Baseline values (mean ± sem, n=6): MAP 66.9 ± 1.8 mmHg, IOP 17.3 ± 0.8 mmHg, ChorBF 467 ± 54 P.U. Facial nerve stimulation with 8 Hz under baseline conditions causes a significant increase of ChorBF 660 ± 80 P.U. and IOP 20.7 ± 1.6 mmHg and a non significant decrease of MAP 61.1 ± 5.0 mmHg. The effects of 20 Hz stimulation did not differ significantly from the 8 Hz results (MAP 68.1 ± 5.0, IOP 22.86 ± 2.0, ChorBF 688 ± 73). Non selective inhibition of the nitric oxide synthases with L‐NAME (20 mg/kg) changed the vasodilatory effects of the two stimulation frequencies. The relative effect of 8 Hz stimulation was significantly smaller than the effect of 20 Hz stimulation. However, baseline blood flow after L‐NAME was lower than under baseline conditions. Conclusion 8Hz and 20 Hz parasympathetic stimulation had similar effects before but not after non selective NOS inhibition. However, no dose of L‐NAME completely suppressed the effect of parasympathetic stimulation.

Measurements and mapping of 282,420 nerve fibers in the S1–5 nerve roots

The study aims to analyze nerve fiber types in the sacral nerve roots as a prerequisite for stimulation. One-micrometer cross-sections of human ventral and dorsal S1-5 roots were stained with osmium and toluidine blue. The total fiber diameter and myelin sheath were measured in 282,420 nerve fibers. The analysis revealed the following 3 main nerve fiber types: Aalpha fibers (diameter 6-14 microm), Agamma fibers (diameter 2-4 microm), and B fibers (diameter < 2 microm). The B fibers were absent in S-1, present in some S-2 fascicles, and abundant from S-3 to S-5. The Aalpha fibers dominated the S-1 roots and most fascicles of S-2 roots. In the S3-5 roots, only a few Aalpha fibers were present. The relative occurrence of Agamma fibers increased from S-1 to S-5. In dorsal roots, Agamma fibers represented approximately 70% of all nerve fibers in every root and fascicle. The B fibers represented efferent parasympathetic fibers. These fibers were concentrated in certain areas of the nerve roots, not randomly distributed. The Aalpha fibers innervate lower-extremity muscles and sphincters. The inverse correlation of Aalpha and Agamma fibers in the ventral roots from S-1 to S-5 is surprising. In dorsal roots, Agamma fibers may conduct pain, touch, and temperature signals. Highly selective fiber stimulation specific for type, location, and direction may improve sacral nerve stimulation for a spastic bladder in paraplegic individuals.

Involvement of vasoactive intestinal polypeptide in the parasympathetic vasodilatation of the rat masseter muscle

The parasympathetic vasodilatory fibres are known to innervate vessels in a rat masseter muscle via both cholinergic and non-cholinergic mechanisms. However, the non-cholinergic mechanisms are still unclear. Recently, vasoactive intestinal polypeptide (VIP) was convincingly shown to be involved in the parasympathetic vasodilatation in orofacial areas, such as submandibular glands and lower lip. However, very little is known about the rat masseter muscle. The present study was designed in the rat masseter muscle to assess (1) whether the parasympathetic nerve innervating vessels have VIP immunoreactivities, (2) whether intravenous administration of VIP induces the vasodilatation, and (3) effects of selective VIP receptor antagonist ([4Cl- d-Phe 6, Leu 17] VIP) in the presence or absence of atropine on the parasympathetic vasodilatation. The VIP immunoreactivities were found at two sites of the parasympathetic otic ganglion and nerve fibres located around vessels. The intravenous administration of VIP induced the vasodilatation, and [4Cl- d-Phe 6, Leu 17] VIP markedly decreased the vasodilatation evoked by VIP administration. The parasympathetic vasodilatation was not inhibited by [4Cl- d-Phe 6, Leu 17] VIP. However, treatment with [4Cl- d-Phe 6, Leu 17] VIP markedly decreased the parasympathetic vasodilatation when [4Cl- d-Phe 6, Leu 17] VIP was administered together with atropine. These results suggest that (1) VIP exists in the postganglionic parasympathetic nerve innervating the vessels in the masseter muscle, (2) the intravenous administration of VIP induces the vasodilatation in the masseter muscle, and (3) VIP may be involved in the parasympathetic vasodilatation in the masseter muscle when muscarinic cholinergic receptors are deactivated by either atropine or the suppression of the ACh release.

Direct evidence of nitric oxide release from neuronal nitric oxide synthase activation in the left ventricle as a result of cervical vagus nerve stimulation

Information regarding vagal innervation in the cardiac ventricle is limited and the direct effect of vagal stimulation on ventricular myocardial function is controversial. We have recently provided indirect evidence that the anti-fibrillatory effect of vagus nerve stimulation on the ventricle is mediated by nitric oxide (NO). The aim of this study was to provide direct evidence for the release of nitric oxide in the cardiac ventricle during stimulation of the efferent parasympathetic fibres of the cervical vagus nerve. The isolated innervated rabbit heart was employed with the use of the NO fluorescent indicator 4,5-diaminofluorescein diacetate (DAF-2 DA) during stimulation of the cervical vagus nerves and acetylcholine perfusion in the absence and presence of the non-specific NO synthase inhibitor NG-nito-L-arginine (L-NNA) and the neuronal NO synthase selective inhibitor 1-(2-trifluormethylphenyl)imidazole (TRIM). Using the novel fluorescence method in the beating heart, we have shown that NO-dependent fluorescence is increased by 0.92 +/- 0.26, 1.20 +/- 0.30 and 1.91 +/- 0.27% (during low, medium and high frequency, respectively) in the ventricle in a stimulation frequency-dependent manner during vagus nerve stimulation, with comparable increases seen during separate stimulation of the left and right cervical vagus nerves. Background fluorescence is reduced during perfusion with L-NNA and the increase in fluorescence during high frequency vagal stimulation is inhibited during perfusion with both L-NNA (1.97 +/- 0.35% increase before L-NNA, 0.00 +/- 0.02% during L-NNA) and TRIM (1.78 +/- 0.18% increase before TRIM, -0.11 +/- 0.08% during TRIM). Perfusion with 0.1 microM acetylcholine increased NO fluorescence by 0.76 +/- 0.09% which was blocked by L-NNA (change of 0.00 +/- 0.03%) but not TRIM (increase of 0.82 +/- 0.21%). Activation of cardiac parasympathetic efferent nerve fibres by stimulation of the cervical vagus is associated with NO production and release in the ventricle of the rabbit, via the neuronal isoform of nitric oxide synthase.