Effects of snuff on regional blood flow to the cheek and tongue of anesthetized dogs

Tobacco Use and Periodontal Disease-The Role of Microvascular Dysfunction

Periodontal disease consists in highly prevalent wide-ranging inflammatory conditions that affect the supporting apparatus of teeth. Tobacco use is the most important risk factor for periodontal disease as it increases disease severity and periodontal surgery complications. Tobacco use is harmful for the vasculature by causing microvascular dysfunction, which is known to negatively affect periodontal disease. To the author's knowledge this paper is the first comprehensive review on the mechanisms by which tobacco use affects oral microcirculation and impacts the pathophysiology of periodontal disease. In healthy subjects, acute nicotine administration or tobacco use (smoking/smokeless forms) increases the blood flow in the oral mucosa due to local irritation and increased blood pressure, which overcome neural- and endocrine-mediated vasoconstriction. Chronic tobacco smokers display an increased gingival microvascular density, which is attributed to an increased capillary recruitment, however, these microcirculatory units show higher tortuosity and lower caliber. These morphological changes, together with the repetitive vasoconstrictive insults, contribute to lower gingival perfusion in chronic smokers and do not completely regress upon smoking cessation. In periodontal disease there is considerable gingival inflammation and angiogenesis in non-smokers which, in chronic smokers, are considerably suppressed, in part due to local immune suppression and oxidative stress. Tobacco exposure, irrespective of the form of use, causes long-term microvascular dysfunction that increases the risk of complications due to the natural disease course or secondary therapeutic strategies.

The pharmacology of nitric oxide in the peripheral nervous system of blood vessels

Unanticipated, novel hypothesis on nitric oxide (NO) radical, an inorganic, labile, gaseous molecule, as a neurotransmitter first appeared in late 1989 and into the early 1990s, and solid evidences supporting this idea have been accumulated during the last decade of the 20th century. The discovery of nitrergic innervation of vascular smooth muscle has led to a new understanding of the neurogenic control of vascular function. Physiological roles of the nitrergic nerve in vascular smooth muscle include the dominant vasodilator control of cerebral and ocular arteries, the reciprocal regulation with the adrenergic vasoconstrictor nerve in other arteries and veins, and in the initiation and maintenance of penile erection in association with smooth muscle relaxation of the corpus cavernosum. The discovery of autonomic efferent nerves in which NO plays key roles as a neurotransmitter in blood vessels, the physiological roles of this nerve in the control of smooth muscle tone of the artery, vein, and corpus cavernosum, and pharmacological and pathological implications of neurogenic NO have been reviewed. This nerve is a postganglionic parasympathetic nerve. Mechanical responses to stimulation of the nerve, mainly mediated by NO, clearly differ from those to cholinergic nerve stimulation. The naming "nitrergic or nitroxidergic" is therefore proposed to avoid confusion of the term "cholinergic nerve", from which acetylcholine is released as a major neurotransmitter. By establishing functional roles of nitrergic, cholinergic, adrenergic, and other autonomic efferent nerves in the regulation of vascular tone and the interactions of these nerves in vivo, especially in humans, progress in the understanding of cardiovascular dysfunctions and the development of pharmacotherapeutic strategies would be expected in the future.

The involvement of nervous and some inflammatory response mechanisms in the acute snuff-induced gingival hyperaemia in humans

BACKGROUND AND AIM

Tobacco users and especially cigarette smokers are at higher risk than non-smokers for periodontal disease. The pathogenic mechanism has been proposed to be the vasoconstrictive properties of nicotine, with reduced gingival blood flow (GBF) as a contributing factor in the development of periodontal disease. However, in a previous study in humans, we found GBF to increase in response to acute exposure to snuff. The present study was designed to investigate whether the tobacco-induced acute GBF increase is dependent on intact nervous conduction. We further investigated the effect of piroxicam (NSAID) and dexchlorpheniramin (DCPA) (antihistamine) on the snuff-induced responses in the gingiva, to see if chemical mediators of inflammation also influenced the response.

MATERIAL AND METHODS

Laser Doppler flowmetry (LDF) was used to measure gingival blood flow bilaterally in the buccal maxillary gingiva, in the forehead skin and in the thumb. Also arterial blood pressure (BP) and heart rate (HR) were monitored. Infraorbital nerve block anaesthesia (INB), superficial mucosal anaesthesia, 20 mg piroxicam or 2 mg DCPA were used in combination with snuff to study the vascular responses to 500 mg snuff (1% nicotine).

RESULTS

Snuff induced a rapid increase in GBF that was higher than the increase in BP, indicating an active vasodilatation. The snuff-induced vasodilatation was partly blocked by INB and more so by superficial mucosal anaesthesia. Piroxicam and DCPA exerted diverse effects on vascular homeostasis but had no effect on the snuff-induced vasodilatation in the gingiva.

CONCLUSIONS

The results of this study confirm that snuff induces local gingival vasodilatation, and imply that this vasodilatation most likely is a summation of responses due to both autonomic and antidromic reflex mechanisms. We further discuss the possible involvement of the nervously mediated effects of tobacco and nicotine on vascular homeostasis and in tobacco-associated periodontitis.

Mechanisms underlying constrictor and dilator responses to perivascular nerve stimulation in canine lingual arteries

In isolated canine lingual arteries denuded of the endothelium, transmural electrical stimulation (2-20 Hz) produced a frequency-related contraction which was not significantly influenced by prazosin but which was reversed to a relaxation by alpha,beta-methylene ATP. The responses were abolished by tetrodotoxin. The stimulation-induced relaxation was abolished by treatment with NG-nitro-L-arginine (L-NA, 10(-6) M) and restored by the addition of L-arginine. Neurogenic relaxation resistant to L-NA was not observed after electrical stimulation, even though the pulse width and stimulus intensity were raised. Under treatment with prazosin, alpha,beta-methylene ATP and indomethacin, the arterial strips responded to nicotine (10(-4) M) with a marked relaxation that was abolished by hexamethonium. The relaxation was significantly inhibited but not abolished by L-NA (10(-5) M), and raising the concentration of the inhibitor to 10(-4) M, did not produce additional inhibition. In the strips treated with L-NA, the nicotine-induced relaxation was abolished or markedly reduced under desensitization with vasoactive intestinal peptide (VIP) or calcitonin gene-related peptide (CGRP) and by treatment with high concentrations of beraprost, a stable analog of prostaglandin I2, but was unaffected by CGRP or VIP receptor antagonists. Relaxant responses to a low concentration of nicotine (5 x 10(-6) M) were abolished by L-NA and restored by L-arginine. Histochemical study demonstrated many nerve fibers and bundles containing NADPH diaphorase in the adventitia of the arteries. It is concluded that the neurogenic arterial contraction is induced mainly by ATP via stimulation of P2X purinoceptors, and that the relaxation induced by electrical stimulation or a low concentration of nicotine is mediated by nitric oxide (NO) released from perivascular nerves. In high concentrations, nicotine elicits marked relaxations possibly due to the liberation of NO from the nerve and also vasodilator substances that increase the content of cyclic AMP in the tissue. CGRP and VIP are unlikely to be involved.

Injury proneness in infantry conscripts undergoing a physical training programme: smokeless tobacco use, higher age, and low levels of physical fitness are risk factors

Musculoskeletal injuries represent an adverse event of strenuous physical activity. The aim of the present study was to identify pretraining factors that may predispose to such injuries. Risks of injury according to age, body composition, previous physical activity, physical fitness, use of smokeless tobacco (moist snuff) and smoking habits were determined in a population of 480 male conscripts in the army. Data were obtained by questionnaire, height and weight measurements, and from a 3000-metre run test prior to a 10-week period of basic military and physical training. Injuries were registered by doctors attached to the training camp. Every fourth conscript sustained one or more musculoskeletal injuries during the training period. Low back pain, overuse knee injuries, Achilles tendinitis, and sprains of joint capsules or ligaments were the most frequent diagnosis groups. Subjects aged 22 years and more, the least active persons before call-up, those who thought they were less fit than the average, the slowest one-third in the 3000-metre run test, smokers of more than 10 cigarettes a day, and snuff-takers suffered more injuries according to univariate analyses. Multiple logistic regression analysis showed that age, self-assessed physical fitness and snuff-taking were mutually independent risk factors of high statistical significance.