Clinical and radiographic periodontal status in hypertensive patients with or without obstructive sleep apnea 10 years after diagnosis and CPAP initiation.

OBJECTIVES: Through inflammation and hyposalivation, obstructive sleep apnea (OSA) is suggested to affect periodontal status over time. Our aim was to compare the clinical and radiographic periodontal status of hypertensive patients with or without long-term presence of OSA, treated or untreated with continuous positive airway pressure treatment (CPAP). MATERIALS AND METHODS: In 2007-2009, a screening for OSA was conducted among 394 hypertensive primary care patients. Polygraphy was used to create three groups: no OSA, non-CPAP, or adherent CPAP based on the apnea hypopnea index (AHI). After 10 years, a cross-sectional sleep and periodontal examination including a clinical and radiographic examination, a questionnaire, and a matrix metalloproteinase-8 (MMP-8) chair-side test was conducted. Based on levels of alveolar bone, bleeding on probing (BoP), and probing pocket depth (PPD), patients were categorized into four periodontal stages: periodontal health/gingivitis and three periodontal disease stages. Periodontal status and periodontal stages were compared between the OSA (n = 49), non-CPAP (n = 38), or adherent CPAP (n = 34) groups. RESULTS: The 121 patients (53% women) had a median age of 71 years. No differences were seen between the OSA groups regarding median number of teeth (p = .061), teeth/implants, (p = .107), plaque index (p = .245), BoP (p = .848), PPD ≥ 4 mm (p = .561), PPD ≥ 6 mm (p = .630), presence of MMP-8 (p = .693) except for bone loss (p = .011). Among patients with stage periodontal health/gingivitis a significant difference was seen, as 70% of those were categorized as no OSA, 20% as non-CPAP, and 10% as adherent CPAP (p = .029). Differences were not seen in periodontal disease stages. CONCLUSIONS: Hypertensive patients with obstructive sleep apnea (OSA) did not have an adverse clinical periodontal status compared to patients without OSA. However, when combining radiographic and clinical status into periodontal stages, patients without OSA more frequently exhibited periodontal health or gingivitis compared to patients without OSA, regardless of CPAP treatment.

The effect of reconstructive techniques as treatment modality for peri-implant osseous defects - a systematic review and meta-analysis.

OBJECTIVES: The aim of this systematic review is to compare conventional peri-implant flap surgery and reconstructive surgical techniques regarding evidence of remission from peri-implantitis. MATERIAL AND METHODS: Searches were made among randomized controlled trials evaluating clinical aspects and the changes in marginal bone level before and after surgical treatment of peri-implantitis, with and without bone substitute. RESULTS: Nine published articles and 442 patients were eligible for inclusion in the study. Reconstructive techniques exhibited a greater extent of defect fill than conventional surgical techniques alone. No significant differences could be found for clinical measures of peri-implant disease (bleeding on probing and reduction of probing depth) from baseline to the 12-month follow-up. CONCLUSIONS: With regards to the clinical measures of disease, our review shows that there are no differences between open flap debridement and regenerative surgery. From an esthetic standpoint, it may however be that regenerative measures may lead to improvement but further publications with this focus will be necessary to verify this.

The long-term impact of alveolar ridge preservation with xenograft bone mineral on peri-implant health after 5 years in function: A retrospective cohort study of 108 patients assessed clinically and radiologically.

OBJECTIVES: When teeth are lost, dental implants contribute to improved oral function and quality of life. Limitations in dental implant placement arising from poor bone anatomy may be circumvented via alveolar ridge preservation (ARP). The aim is to evaluate the long-term impact of ARP on peri-implant health and the relationship with common risk indicators such as smoking and history of periodontitis. MATERIALS AND METHODS: One hundred and eight patients were enrolled in this retrospective cohort study with 308 implants. Of these, ∼41% were placed in bone sites that had previously received ARP with deproteinized bovine bone mineral xenograft. Association between baseline variables: ARP, age, gender, number of implants per patient, anatomical site, smoking, and previous history of grade III/IV periodontitis, and outcome variables: mucositis, peri-implantitis, implant loss, full-mouth plaque score (FMPS), full-mouth bleeding score, and marginal bone loss (MBL) was evaluated using both univariate and multivariate models. RESULTS: After 5 years, the overall survival rate was 93.7%. The occurrence of peri-implantitis was 21.3% and the extent of MBL was ~2.2 mm. Both peri-implantitis occurrence and MBL were comparable between ARP+  and ARP- . Smoking is associated with higher FMPS and MBL. CONCLUSIONS: The findings indicate that peri-implant health can be maintained around dental implants for up to 5 years in ARP+  sites using Bio-Oss®. Smoking is a major risk indicator for peri-implantitis, whereas the association between history of periodontitis and the risk of peri-implantitis, based on this specific, well-maintained cohort and the specific implants used, remains inconclusive.

Do Probiotics Cause a Shift in the Microbiota of Dental Implants-A Systematic Review and Meta-Analysis.

Objective: The primary aim of this current systematic review and meta-analysis was to evaluate the potential microbiological effect of probiotics on the implant microbiota. The secondary aim was to evaluate if probiotics have any effect as an adjunct to non-surgical peri-implant treatment in reducing peri-implant mucositis and peri-implantitis clinical parameters-bleeding on probing, modified Gingival Index, and pocket depth. Methods: The research focus questions were constructed in accordance with the Participants, Intervention, Comparison, and Outcomes (PICO) criteria, and a PROSPERO protocol was registered. A comprehensive systematic search in MEDLINE via the PubMed, Scopus, and Web of Science Core Collection databases was conducted. Two independent reviewers screened the reports based on the PICO criteria-inclusion and exclusion criteria. Results: In total, 467 records were identified, and ultimately, 7 papers were included: 3 papers in the qualitative synthesis of microbiological effect and 4 in the meta-analysis synthesis on pocket depth. The data synthesis showed that probiotics had no detectable effect on the implant microflora, and in the following data synthesis, no clinical peri-implantitis variable showed a significantly beneficial effect from probiotics in the test group compared to the control group. Conclusion: Within the limitations of this review, the oral implant microflora is not affected by probiotics nor do probiotics add any effect to the conventional non-surgical treatment of peri-implant mucositis and peri-implantitis.

Peri-implantitis: Summary and consensus statements of group 3. The 6th EAO Consensus Conference 2021.

OBJECTIVE: To evaluate the influence of implant and prosthetic components on peri-implant tissue health. A further aim was to evaluate peri-implant soft-tissue changes following surgical peri-implantitis treatment. MATERIALS AND METHODS: Group discussions based on two systematic reviews (SR) and one critical review (CR) addressed (i) the influence of implant material and surface characteristics on the incidence and progression of peri-implantitis, (ii) implant and restorative design elements and the associated risk for peri-implant diseases, and (iii) peri-implant soft-tissue level changes and patient-reported outcomes following peri-implantitis treatment. Consensus statements, clinical recommendations, and implications for future research were discussed within the group and approved during plenary sessions. RESULTS: Data from preclinical in vivo studies demonstrated significantly greater radiographic bone loss and increased area of inflammatory infiltrate at modified compared to non-modified surface implants. Limited clinical data did not show differences between modified and non-modified implant surfaces in incidence or progression of peri-implantitis (SR). There is some evidence that restricted accessibility for oral hygiene and an emergence angle of >30 combined with a convex emergence profile of the abutment/prosthesis are associated with an increased risk for peri-implantitis (CR). Reconstructive therapy for peri-implantitis resulted in significantly less soft-tissue recession, when compared with access flap. Implantoplasty or the adjunctive use of a barrier membrane had no influence on the extent of peri-implant mucosal recession following peri-implantitis treatment (SR). CONCLUSIONS: Prosthesis overcontouring and impaired access to oral hygiene procedures increases risk for peri-implantitis. When indicated, reconstructive peri-implantitis treatment may facilitate the maintenance of post-operative peri-implant soft-tissue levels.

Influence of single nucleotide polymorphisms among cigarette smoking and non-smoking patients with coronary artery disease, urinary bladder cancer and lung cancer.

INTRODUCTION: Cigarette smoke is suggested to be a risk factor for coronary artery disease (CAD), urinary bladder cancer (UBCa) or lung cancer (LCa). However, not all heavy smokers develop these diseases and elevated cancer risk among first-degree relatives suggests an important role of genetic factor. METHODS: Three hundred and ten healthy blood donors (controls), 98 CAD, 74 UBCa and 38 LCa patients were included in this pilot study. The influence of 92 single nucleotide polymorphisms (SNPs) and impact of cigarette smoking were analysed. RESULTS: Out of 92 SNPs tested, differences in distribution of 14 SNPs were detected between controls and patient groups. Only CTLA4 rs3087243 showed difference in both CAD and UBCa patient group compared to control group. Stratified by smoking status, the impact of smoking was associated to frequencies of 8, 3 and 4 SNPs in CAD, UBCa, LCa patients, respectively. None of these 92 SNPs showed a statistically significant difference to more than one type of disease among smoking patients. In non-smoking patients, 7, 3 and 6 SNPs were associated to CAD, UBCa, LCa, respectively. Out of these 92 SNPs, CTLA4 rs3087243 was associated to both non-smoking CAD and UBCa. The XRCC1 rs25487 was associated to both non-smoking UBCa and LCa. CONCLUSION: SNPs might be important risk factors for CAD, UBCa and LCa. Distribution of the SNPs was specific for each patient group, not a random event. Impact of cigarette smoking on the disease was associated to the specific SNP sequences. Thus, smoking individuals with SNPs associated to risk of these serious diseases is an important target group for smoking cessation programs.

Does Smoking Impair Bone Regeneration in the Dental Alveolar Socket?

Smoking is a major risk factor for dental implant failure. In addition to higher marginal bone loss around implants, the cellular and molecular responses to injury and implant physicochemical properties are also differentially affected in smokers. The purpose of this work is to determine if smoking impairs bone microstructure and extracellular matrix composition within the dental alveolar socket after tooth extraction. Alveolar bone biopsies obtained from Smokers (> 10 cigarettes per day for at least 10 years) and Ctrl (never-smokers), 7-146 months after tooth extraction, were investigated using X-ray micro-computed tomography, backscattered electron scanning electron microscopy, and Raman spectroscopy. Both Smokers and Ctrl exhibited high inter- and intra-individual heterogeneity in bone microstructure, which varied between dense cortical and porous trabecular architecture. Regions of disorganised/woven bone were more prevalent during early healing. Remodelled lamellar bone was predominant at longer healing periods. Bone mineral density, bone surface-to-volume ratio, mineral crystallinity, the carbonate-to-phosphate ratio, the mineral-to-matrix ratio, the collagen crosslink ratio, and the amounts of amino acids phenylalanine and proline/hydroxyproline were also comparable between Smokers and Ctrl. Bone microstructure and composition within the healing dental alveolar socket are not significantly affected by moderate-to-heavy smoking.

Extracellular matrix composition during bone regeneration in the human dental alveolar socket.

Within the dental alveolar socket, the sequence of events following tooth extraction involves deposition of a provisional connective tissue matrix that is later replaced by woven bone and eventually by lamellar bone. Bone regeneration within the dental alveolar socket is unique since the space occupied by the root(s) of a tooth does not originally contain any bone. However, extracellular matrix composition of the healing alveolar socket has not previously been investigated. Here, alveolar bone biopsies representing early (7-46 months, < 4y) and late (48-60 months; 4-5y) healing periods were investigated using Raman spectroscopy, X-ray micro-computed tomography and backscattered electron scanning electron microscopy. Partially or completely edentulous individuals and those with a smoking habit were not excluded. Between < 4y and 4-5y, mineral crystallinity and bone mineral density increase, phenylalanine, proline/hydroxyproline, and bone surface-to-volume ratio decrease, while the carbonate-to-phosphate ratio, the mineral-to-matrix ratio, and the collagen crosslink ratio remain relatively unchanged. Observed exclusively at 4-5y, hypermineralised osteocyte lacunae contain spherical and rhomboidal mineral nodules. Spearman correlation analysis reveals several significant, high (ρ = 0.7-0.9; p ≤ 0.01) and moderate (ρ = 0.5-0.7; p ≤ 0.01) correlations. Mineral crystallinity and proline/hydroxyproline, the carbonate-to-phosphate ratio and phenylalanine, mineral crystallinity and bone surface-to-volume ratio, the carbonate-to-phosphate ratio and bone surface-to-volume ratio, proline/hydroxyproline and bone mineral density, and bone mineral density and bone surface-to-volume ratio are negatively correlated. Mineral crystallinity and bone mineral density, and proline/hydroxyproline and bone surface-to-volume ratio are positively correlated. Although bone regeneration in the dental alveolar socket follows typical bone healing patterns, the compositional and microstructural patterns reveal mature bone at <4y with indications of better mechanical competence at 4-5y.

Cigarette smoking affects microRNAs and inflammatory biomarkers in healthy individuals and an association to single nucleotide polymorphisms is indicated.

BACKGROUND: Cigarette smoke induces inflammation and remodels immune response. Genetic and epigenetic alterations might be involved in the pathogenesis of smoking related diseases. In this study, we investigated the effect of smoking on systemic inflammation biomarkers and epigenetic changes at microRNA (miRNA) expression level. We also examined if the levels of inflammatory biomarkers were associated with selected single nucleotide polymorphisms (SNPs). METHOD: From 39 smokers and 101 non-smokers, levels of total white blood cells (WBCs) and its subpopulations, plasma cytokines/chemokines/proteins and miRNAs were analysed. For three biomarkers, C-reactive protein (CRP), MCP-1 and IFN-γ that were affected by smoking, the influence of SNPs was analyzed. RESULT: Elevated levels of total WBCs, neutrophils, monocytes, lymphocytes, CRP, MCP-1, IFN-γ and lower levels of miR-21 were detected in smokers. The elevated levels of IFN-γ in smokers was only statistically significantly associated with rs2069705 AG/GG SNP-genotype. CONCLUSIONS: A lower level of oncomir miRNA-21 and a higher level of immune modelling cytokine IFN-γ detected in smokers could be a protective immune response to cigarette smoke. The higher level of IFN-γ in smokers with a specific SNP genotype also suggests that a genetic interaction with smoking might predict the pathobiology of smoking related disease.

Implant-associated gene expression in the jaw bone of smokers and nonsmokers: A human study using quantitative qPCR.

OBJECTIVES: This study aimed to compare the molecular events in implant-adherent cells and in peri-implant bone during the osseointegration of machined and oxidized titanium implants in smokers and nonsmokers. MATERIALS AND METHODS: Twenty-four smokers and 24 nonsmokers each received machined and anodically oxidized mini-implants. The mini-implants and the surrounding bone were retrieved after 1, 7, and 28 days, for gene expression analysis of selected factors using quantitative polymerase chain reaction (qPCR). RESULTS: Differences between machined and oxidized implants were more evident in the implant-adherent cells than the peri-implant bone. The machined implants revealed higher expression of proinflammatory cytokines, interleukin-8 (IL-8) (in nonsmokers), and tumor necrosis factor-alpha (in nonsmokers and smokers), compared with the oxidized implants. Conversely, the expression of bone formation genes, alkaline phosphatase and osteocalcin, was generally higher at the oxidized implants. In smokers, the temporal pattern revealed the delayed and initial inhibition of osteoblastic and osteoclastic gene expression, respectively, mainly at the machined implants. In contrast, oxidized implants revealed higher expression of bone remodeling, cathepsin K (CatK) and calcitonin receptor, and coupling, receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin, genes after 7 day in smokers. CONCLUSIONS: The implant-adherent cells are more sensitive to surface properties and smoking conditions than the cells in the peri-implant bone. Smoking imposes inhibitory effects on the initial molecular events of osseointegration in the human bone-implant interface. The surface properties of oxidized implants appear to have a beneficial effect on osseointegration by mitigating the smoking-induced negative effects.

Clinical, radiological, and gene expression analyses in smokers and non-smokers, Part 2: RCT on the late healing phase of osseointegration.

BACKGROUND: The mechanisms behind the impact of smoking on osseointegration are not fully understood. PURPOSE: To investigate the initial clinical and molecular course of osseointegration of different implants in smokers and non-smokers in a randomized controlled trial (RCT). MATERIALS AND METHODS: Smoking (n = 16) and non-smoking (n = 16) patients received 3 implant types: machined, oxidized, and laser-modified surfaces. Baseline bone biopsies were retrieved from the implant sites. After 60 and 90 days, the pain score, implant stability quotient (ISQ), and peri-implant crevicular fluid (PICF) gene expression were analyzed. Furthermore, radiological and clinical assessments were made at 90 days. RESULTS: At 90 days, no pain was reported, irrespective of smoking habit. A higher ISQ was found in smokers compared with non-smokers. Marginal bone loss (MBL) was greater in smokers than in non-smokers. The comparison of implant surfaces revealed greater MBL exclusively at the machined implants in smokers. At 90 days in smokers, the PICF around machined implants revealed a higher expression of the proinflammatory cytokine, interleukin-6 (IL-6), and a lower expression of the osteogenic gene, osteocalcin (OC), compared with the PICF around modified implants. Furthermore, OC expression was lower at machined implants in smokers compared with machined implants in non-smokers. After adjustment for age and implant location (maxilla/mandible), multivariate regression revealed the following predictors of MBL: smoking, bleeding on probing at 90 days, hypoxia-inducible factor 1 alpha (HIF-1α) expression at baseline and IL-6 expression in PICF at 90 days. CONCLUSIONS: During the early phase of osseointegration, non-smokers and smokers present a similar, high implant survival. In contrast, smokers present a greater MBL, particularly at machined implants. HIF-1α baseline expression in the recipient bone and IL-6 expression in PICF cells are important molecular determinants for MBL after 90 days. It is concluded that smoking has an early effect on osseointegration, which is dependent on the implant surface properties and the local host response.

Gene expression in peri-implant crevicular fluid of smokers and nonsmokers. 1. The early phase of osseointegration.

BACKGROUND: Smoking is a risk factor for dental implants. The mechanisms behind the impact of smoking on osseointegration are not fully understood. PURPOSE: To investigate the initial molecular and clinical course of osseointegration of different titanium implants in smokers and nonsmokers. MATERIALS AND METHODS: Smoker (n = 16) and nonsmoker (n = 16) patients were included. Each patient received three implant types: machined, oxidized and laser-modified surfaces. After 1, 7, 14, and 28 days, the peri-implant crevicular fluid (PICF) was sampled for gene expression analysis of selected factors involved in early processes of osseointegration. Furthermore, pain-score (VAS), resonance frequency analysis (RFA) and baseline clinical assessments were performed. RESULTS: Early failure of osseointegration, associated with a high and sustained perception of pain, was encountered in 3/32 patients. In general, high pain scores were reported during the first days after implantation, irrespective to smoking habit, which correlated to high levels of pro-inflammatory cytokines during the first days after implantation. Higher ISQ values were found in smokers compared to nonsmokers. In smokers exclusively, ISQ values correlated to harder and less atrophic bone quality and quantity, respectively. Smokers displayed a higher expression of osteocalcin (OC), but later peak and lower expression of bone morphogenetic protein (BMP-2) (at 7 days) compared to nonsmokers. In comparison to machined implants, surface-modified implants were associated with higher expression of alkaline phosphatase (ALP) and cathepsin K (CatK) at 28 days in nonsmokers. CONCLUSIONS: During the early phase of osseointegration, postoperative pain is linked to the inflammatory cell response and, may tentatively serve as an indicator of biological complication and implant loss. The present study suggests that smokers have an altered bone composition and (ultra)structure based on the observations that ISQ values are higher and correlate to recipient bone quality and quantity in smokers.

Implant survival and marginal bone loss at turned and oxidized implants in periodontitis-susceptible smokers and never-smokers: a retrospective, clinical, radiographic case-control study.

BACKGROUND: Little is known about the long-term outcome of oxidized surface oral implants, especially in periodontitis-susceptible smokers. The aim of this study is to determine implant survival and marginal bone loss at turned and oxidized implants in smokers and never-smokers with periodontitis. METHODS: Forty smokers and 40 never-smokers with experience of advanced periodontal disease, treated with implants 5 years previously, are included in this study. Groups were matched for sex, oral hygiene, and implant distribution, and patients were subgrouped by implant surface type (turned or oxidized). RESULTS: The overall implant survival rate was 96.9% in never-smokers and 89.6% in smokers. Compared with oxidized implants, turned implants failed more frequently in smokers. In smokers, mean (standard error of the mean) marginal bone loss at 5 years was 1.54 (0.21) mm at turned and 1.16 (0.24) mm at oxidized implants. In never-smokers, significantly greater bone loss was found at oxidized implants, 1.26 (0.15) mm, than at turned implants, 0.84 (0.14) mm. Oxidized implants demonstrated similar bone loss for both groups. Turned implants lost significantly more bone in smokers. Compared with never-smokers, the smokers' likelihood ratio for implant failure was 4.68, 6.40 for turned and 0.00 for oxidized implants. CONCLUSIONS: The results of the study underscore the need for prevention and cessation of smoking. Turned implants failed more frequently and lost more marginal bone in smokers. In contrast, oxidized implants showed similar failure rates and bone loss in smokers and never-smokers. Turned implants displayed less bone loss than oxidized implants in never-smokers. Oxidized surface implants are more suitable for patients susceptible to periodontitis who smoke.

Parasympathetic nerve-evoked protein synthesis, mitotic activity and salivary secretion in the rat parotid gland and the dependence on NO-generation.

Incorporation of radiolabelled leucine and thymidine into trichloroacetic acid-insoluble material of the parotid gland was used as indices of protein synthesis and mitotic activity, respectively, following electrical stimulation of the parasympathetic auriculo-temporal nerve for 30 min in pentobarbitone-anaesthetized rats under adrenoceptor blockade (phentolamine and propranolol, 2mg/kg intravenous of each) in the absence or presence of atropine (2mg/kg intravenous) and without or with nitric oxide synthase inhibitors. In atropinized rats, the parasympathetic non-adrenergic, non-cholinergic (NANC) nerve-evoked mean increases in protein synthesis at a frequency of 10 Hz (142%) and 40 Hz (200%) were not affected in a statistically significant way (124 and 275%, respectively) by the neuronal type NO-synthase inhibitor N(w)propyl-l-arginine (N-PLA) (30 mg/kg intravenous). Neither were the increase (175%) in protein synthesis at 10 Hz in non-atropinized animals affected by N-PLA (180%). The increase (65%) in mitotic activity, 19 h after the end of stimulation at 40 Hz, in the presence of atropine, was not affected by N-PLA (55%). Neither were the increase (95%) in gland content of amylase at this point of observation statistically significant affected by N-PLA (144%). The secretion of fluid and output of amylase from the parotid gland upon nerve stimulation was not affected by N-PLA. When examining the non-selective NO-synthase inhibitor l-NAME (30 mg/kg intravenous) in atropinized rats subjected to stimulation at 10 Hz, neither the increase in protein synthesis nor the evoked fluid response or amylase outputs were affected. Hence, in contrast to an NO-dependent sympathetic-induced protein synthesis and mitosis in the parotid gland, involving the activity of the neuronal type NO-synthase, no support for a parasympathetic-induced protein synthesis (and gain in gland amylase) and mitosis, depending on NO-generation, was found. Likewise, the present findings provide no evidence for a role of NO in the parasym pathetic nerve-evoked fluid secretion and amylase output.

Nitric oxide-dependent mitotic activity in salivary glands of the rat upon sympathetic stimulation.

Incorporation of [3H]thymidine into trichloroacetic acid (TCA)-insoluble material of the parotid and submandibular glands was used as an index of mitotic activity following unilateral electrical stimulation of the sympathetic innervation (20 Hz, 4 min every fifth minute over 34 min). Stimulation under beta-adrenoceptor blockade (propranolol 2 mg/kg, intravenous) alone or combined with alpha-adrenoceptor blockade (phentolamine 2 mg/kg, intravenous) did not increase the rate of [3H]thymidine incorporation into the two types of glands. However, under alpha-adrenoceptor blockade the [3H]thymidine incorporation increased into the parotid glands, by 122% (compared to the glands on the contralateral side), but not into the submandibular glands. In the presence of the neuronal type NO-synthase (nNOS) blocker N-PLA (30 mg/kg, intravenous) or the unselective NO-synthase blocker L-NAME (30 mg/kg, intravenous), this increase was reduced to 49 and 47%, respectively. Thus, the major part of the sympathetically nerve-evoked beta-adrenoceptor-mediated mitotic response was found to depend on the activity of neuronal type NO-synthase to generate NO. Since the sympathetic nerve fibres of the parotid gland lack NO-synthase, the neuronal type NO-synthase subjected to the inhibitors is likely to be of parenchymal origin.

Nitric oxide-dependent protein synthesis in parotid and submandibular glands of anaesthetized rats upon sympathetic stimulation or isoprenaline administration.

In anaesthetized female rats, the beta-adrenoceptor agonist isoprenaline was intravenously infused (20 microg kg(-1) min(-1)) for 30 min or the ascending cervical sympathetic nerve trunk was intermittently stimulated (50 Hz, 1 s every tenth second) on one side for 30 min. The incorporation of [3H]leucine into trichloroacetic acid (TCA)-insoluble material was used as an index of protein synthesis. In response to isoprenaline, the [3H]leucine incorporation increased by 79% in the parotid glands and by 82% in the submandibular glands. The neuronal type NO-synthase inhibitor N-PLA, reduced (P < 0.001) this response to 26% and 20%, respectively. Sympathetic stimulation under alpha-adrenoceptor blockade increased the [3H]leucine incorporation by 192% in the parotid glands and by 35% in the submandibular glands. N-PLA reduced the corresponding percentage figures to 86% (P < 0.01) and 8% (P < 0.05). When tested in the parotid glands, the non-selective NO-synthase inhibitor L-NAME reduced (P < 0.01) the nerve-evoked response to 91%. The increase in [3H]leucine incorporation in response to sympathetic stimulation under beta-adrenoceptor blockade was not affected by N-PLA in the parotid (139% versus 144%) and submandibular glands (39% versus 34%). In non-stimulated glands, the [3H]leucine incorporation was not influenced by the NO-synthase inhibitors. In conclusion, beta-adrenoceptor mediated salivary gland protein synthesis is largely dependent on NO generation by neuronal type NO-synthase, most likely of parenchymal origin.

Nitric oxide-dependent in vitro secretion of amylase from innervated or chronically denervated parotid glands of the rat in response to isoprenaline and vasoactive intestinal peptide.

The basal in vitro release of amylase was similar from rat parotid lobules of innervated and chronically denervated glands and was unaffected by the inhibitors used in this study. The secretion of amylase induced by isoprenaline or vasoactive intestinal peptide (VIP) was reduced by one-third to one-half from the lobules of the innervated glands and even more so from the lobules of the denervated glands by ODQ, an inhibitor of soluble guanyl cyclase which is activated by nitric oxide (NO) and catalyses the cGMP production. The use of N (omega)-propyl-L-arginine (N-PLA) revealed that the evoked secretion of amylase in the denervated glands depended on the activity of neuronal type NO synthase to synthesize NO. Since the denervated gland is virtually devoid of NO synthase-containing nerve fibres, the neuronal type NO synthase was most probably of a non-neuronal source. NO-dependent amylase secretion was agonist related, since amylase secretion evoked by bethanechol and neuropeptide Y was not reduced by ODQ or N-PLA. Hence, under physiological conditions, activation of beta-adrenoceptors (sympathetic activity) and VIP receptors (parasympathetic activity) is likely to cause secretion of parotid amylase partly through a NO/cGMP-dependent intracellular pathway involving the activity of neuronal type NO synthase, possibly of acinar origin.