Changes in nasal mucosal blood flux and air-flow resistance on unilateral histamine challenge

Medical Treatment of Nasal Airway Obstruction

Nasal obstruction is a common, and potentially debilitating, problem. It is caused by a combination of structural factors and/or mucosal swelling/inflammation. The medical treatment of nasal obstruction is aimed at decreasing mucosal inflammation and edema and is generally guided by the underlying cause. Several different drug classes are commonly used in the treatment of nasal obstruction, each with different indications, and pros and cons to their use. This article discusses the most commonly used therapies for nasal obstruction. Current evidence on the efficacy and side effect profile of each therapy is reviewed.

Effects of Substance P and Methacholine on Mucosal Blood Flow in the Upper Airways

The aims of the present investigation were to examine the in vivo effects of substance P (SP) and methacholine on blood flow measured by laser Doppler technique in the maxillary sinus of the rabbit and in the human nasal mucosa. In the rabbit, the test substances were administered by intra-arterial catheter, and the laser Doppler probe was inserted into the maxillary sinus through a trepanation in the anterior wall. In the human nose, the laser Doppler probe was directed toward the nasal septum at the level of the anterior margin of the middle turbinate, and the test substances were administered as aerosols into the ipsilateral nostril. In the rabbit maxillary sinus, both SP and methacholine increased the blood flow, the maximum increases obtained being 13.5 ± 3.1% and 39.0 ± 5.6% after challenges with SP at 0.1 μg/kg and methacholine at 0.5 μg/kg, respectively. The rabbits displayed a decrease in blood flow after challenges at higher dosages of both SP and methacholine, accompanied by a simultaneous fall in systemic blood pressure. Atropine given IV five minutes before methacholine abolished the effects of this compound in the rabbit. The blood flow in the human nose was unaffected by saline controls, whereas it was increased both by SP and by methacholine, the increases being 34.9 ± 6.0% after challenges with SP 1.0 nmol and 119.2 ± 15.1% after challenges with methacholine 5.0 μmol. According to acoustic rhinometry, neither SP nor methacholine had, at the doses used, any effect on human nasal patency. Pretreatment with lidocaine hydrochloride spray into the human nose did not affect the increase in nasal blood flow induced by SP, but abolished the methacholine-evoked blood flow increase. Pretreatment with ipratropium bromide spray into the human nose abolished the increase in blood flow induced by methacholine. The results of the present study indicate that blood flow in the upper airways of humans and rabbits may increase due to release of SP or acetylcholine in vivo, an event that occurs after exposure to airway irritants. The vasodilation in the human nose produced by acetylcholine may be due to a neurogenic reflex, in contrast to the effect of SP.

[The NTP in allergy research : open questions regarding nasal provocation tests using allergens]

The nasal provocation test (NPT) is a simple procedure with high specificity and sensitivity that is used in the investigation of allergic and nonallergic diseases. Uniform standards are of particular importance in the clinical setting and for the comparability of clinical and basic allergy research. These standards should cover the composition, dosage and pharmacological formulation of provocative substances (e.g. allergen extracts), the necessity of titration, allergen application methods and the evaluation criteria for a positive NPT reaction. Detection of various mediators and cytokines in nasal discharge can be very useful in the late phase reactions. NPT finds specific applications in studies of local IgE secretion in the nasal mucosa, the diagnosis of analgesic intolerance and in assessments of the efficacy of specific immunotherapies. Additional parameters warranting further evaluation include provocation with cold dry air in nasal hyperreactivity patients and nasal nitric oxide formation. Determination of nasal blood flow during NPT provides an additional clinical parameter.

Canine model of nasal congestion and allergic rhinitis

The ragweed- and histamine-induced decreases in nasal patency in cohorts of ragweed-sensitized and nonsensitized dogs were assessed. The volume of nasal airways (V(NA)) was assessed by acoustic rhinometry and resistance to airflow (R(NA)) by anterior rhinomanometry. Histamine delivered to the nasal passages of five dogs caused a rapid and prolonged increase in R(NA) (0.75 +/- 0.26 to 3.56 +/- 0.50 cmH(2)O. l(-1). min), an effect that was reversed by intranasal delivery of aerosolized phenylephrine. Ragweed challenge in five ragweed-sensitized dogs increased R(NA) from 0.16 +/- 0.02 to 0.53 +/- 0.07 cmH(2)O. l(-1). min and decreased V(NA) from 12.5 +/- 1.9 to 3.9 +/- 0.3 cm(3), whereas administration of saline aerosol neither increased R(NA) nor decreased V(NA). Prior administration of d-pseudoephedrine (30 mg po) attenuated the ragweed-induced increase in R(NA) and decrease in V(NA). Ragweed challenge changed neither R(NA) nor V(NA) in four nonsensitized dogs. Mediator-induced nasal congestion and allergen-induced allergic rhinitis in ragweed-sensitized dogs, which exhibit symptoms similar to human disease, can be used in the evaluation of safety and efficacy of antiallergic activity of potential drugs.

Nasal histamine provocation of tenants in a sick-building residential area

Health problems associated with the indoor climate have aroused an increasing scientific interest, and the term "sick-building syndrome" (SBS), which describes the most frequent symptoms in this context, has been coined. However, it has been difficult to demonstrate objectively any pathophysiological changes in the subjects affected. Thirty-three healthy and nonatopic persons were randomly selected on the basis of answers in a postal questionnaire dealing with discomfort or health symptoms experienced in their home environment. Twenty-three lived in a residential area with indoor climate problems (SBS area) and 10 lived in an area without climate problems (non-SBS area). Twelve persons from the SBS area reported nasal symptoms, which they ascribed to their home environment. The remaining 11 persons from the same area, as well as the 10 subjects from the non-SBS area, had no nasal distress. They were examined with rhinostereometry during histamine provocation. Hyperreactivity, defined as mucosal swelling exceeding 0.4 mm at 5 and 10 minutes after provocation with 0.14 ml of 2 mg/ml histamine chloride, was frequent in the symptomatic SBS group as well as in the asymptomatic SBS group. The analysis of the increment of mucosal swelling for the whole range of histamine chloride concentrations (0.1 mg/ml to 16 mg/ml) showed significantly different growth curves for the three groups in the residential areas and an external reference group, (p < 0.0001). Subjects living in the SBS area were prone to nasal hyperreactivity, whether they reported symptoms from the upper airways or not. The results support the hypothesis that living in an SBS area increases the risk of developing nonspecific nasal hyperreactivity.