Respiratory Tract Of Rats Research Articles

Regulatory peptides in the mammalian respiratory tract.

The quantitative distribution of five biologically active peptides was determined by RIA and immunocytochemistry in various regions of cat, rat, and guinea pig respiratory tracts. Vasoactive intestinal polypeptide (VIP) and substance P were found in higher concentrations than cholecystokinin (CCK), SRIF, and bombesin. In general, higher concentrations were found in the main airways than in lung tissue. Immunocytochemistry localized VIP and substance P to autonomic nerves, whereas bombesin was found in very scattered mucosal endocrine cells of the cat bronchial epithelium. CCK and SRIF could not be convincingly localized by immunocytochemistry because of their low tissue concentrations. Species differences were noted, with high VIP but low substance P concentrations in the main airways of the cat; this relationship was reversed in the rat and guinea pig. Gel permeation chromatography of extracts revealed one peak, coeluting with the pure standard peptide, for CCK-8, SRIF, substance P, and VIP. Bombesin imm...

Effect of sulfur dioxide-sulfate exposure on rat respiratory tract clearance

The effect of a 4 hour exposure to a model sulfur pollutant atmosphere on the clearance of inhaled insoluble tracer particles from the lungs of rats has been studied. The pollutant combination consisted of 5 ppm of sulfur dioxide gas and 1.5 mg/m3 of sulfate aerosol at 80–85% relative humidity. The exposure atmosphere was aged for 30 minutes upstream of the exposure chamber in an aging line in order to provide for gas/particle interactions such as those occurring in industrial and environmental atmospheres. Results indicate that the sulfur pollutant atmosphere did not produce a statistically significant alteration in early (nasopharyngeal and tracheobronchial) or late (parenchymal) clearance rates such as those which have been identified in this laboratory following exposure to ozone-containing atmospheres.

Effect of sulfur dioxide-sulfate exposure on rat respiratory tract clearance.

The effects of a 4 hour exposure to a model sulfur pollutant atmosphere on the clearance of inhaled insoluble tracer particles from the lungs of rats has been studied. The pollutant combination consisted of 5 ppm of sulfur dioxide gas and 1.5 mg/m3 of sulfate aerosol at 80-85% relative humidity. The exposure atmosphere was aged for 30 minutes upstream of the exposure chamber in an aging line in order to provide for gas/ particle interactions such as those occurring in industrial and environmental atmosphere. Results indicate that the sulfur pollutant atmosphere did not produce a statistically significant alteration in early (nasopharyngeal and tracheobronchial) or late (parenchymal) clearance rates such as those which have been identified in this laboratory following exposure to ozone-containing atmospheres.

An electron microscopic study of disturbance of the respiratory tract mucous membrane caused by tetrahydrofuran

Although THF has long been knows as an organic solvent, yet few studies are done on its toxicity. A great volatility is pointed out as one of its physiochemical properties. Therefore, possible exposure of factory workers to THF is an important problem. We studied effects of THF on the mucosa of respiratory tract in rats using an electron-microscope, and clarified its toxic activities.

The histology and fine structure of glands in the rat respiratory tract.

The structure of rat respiratory glands has been investigated by light and electron microscopy. The glands exhibited a tubulo-acinar organization. Individual secretory units were composed of serous tubules or serous demilunes and mucous tubules with narrow lumens at the blind end (proximally), and of mucous ducts with wide lumens which opened to the tracheal lumen distally. Near the junction of the duct with the trachea, mitochondria-rich cells and a few ciliated cells were interspersed with mucous cells. It was found that the histology as well as the ultrastructure of the secretory product of these gland cells varied depending upon the location of the glands in the airway. For this reason, the glands of the epiglottis, larynx and trachea have been described separately. Epiglottal glands consisted of many mucous tubules, a few serous elements and an occasional mucous duct. Laryngeal glands contalned many serous and mucous tubules and a few mucous ducts. Tracheal glands were composed of serous tubules, a few mucous tubules and prominent bucous ducts. Serous tubule cell granules formed a uniform population within a cell profile but varied in cells of the epiglottis, compared with those of the larynx and trachea. Granules in mucous tubule cells differed from those of serous cells. Mucous cell granules also appeared uniform within a single cell but differed from cell to cell and at different levels of the respiratory tract. A particular granule type was predominant at each level. Cells of mucous ducts differed somewhat from those of mucous tubules and comprised two general secretory cell populations. Proximal mucous duct cells contained abundant granules that generally resembled those of mucous tubule cells but were localized in two areas of the cytoplasm. Dilated cisternae of rough endoplasmic reticulum with a bizonal content similar in density of zones seen in mature granules further characterized proximal mucous duct cells. The distal mucous duct cell generally contained sparse apical granules and lacked dilated rough endoplasmic reticulum.

Carbohydrate histochemistry of rat respiratory glands.

AbstractCytochemical methods applied to examination of rat respiratory tract glands have revealed diversity of secretory complex carbohydrates. With the Alcian blue‐periodic acid Schiff (AB‐PAS) and the high iron diamine (HID) techniques at the light microscopic level, certain patterns of glycoprotein content were noted at various levels of the respiratory tract. Serous tubules and demilunes found in abundance in laryngeal and tracheal glands contained neutral glycoprotein. Mucous tubules found in abundance in epiglottal and laryngeal glands and in lesser number in tracheal glands most often produced sulfated glycoprotein. However, mucous tubules in epiglottal and tracheal glands contained a few cells with sialylated glycoprotein, and mucous tubules in some areas in laryngeal glands contained mainly cells producing sialylated glycoprotein. Mucous ducts found in abundance in lower laryngeal and tracheal glands formed mainly sialylated glycoprotein and contained infrequent cells with sulfated glycoprotein. The type of glycoprotein found in each cell type by light microscopy was confirmed at the ultrastructural level by the periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP), dialyzed iron (DI) and high iron diamine (HID) methods. Serous cell granules displayed light reactivity with the PA‐TCH‐SP method and no DI or HID affinity and were judged to contain sparse neutral glycoprotein. Serous granules disclosed negative central foci with the PA‐TCH‐SP method. Granules of most mucous tubule cells stained strongly with the PA‐TCH‐SP and HID procedures and contained abundant sulfated glycoprotein. Occasional mucous tubules stained with the PA‐TCH‐SP but not with the HID method and apparently corresponded with cells judged to form sialylated glycoprotein from their blue staining with the HID‐AB sequence. Two zones within individual granules in some cells revealed different HID staining intensity and appeared to differ in the amount or kind of sulfated glycoprotein they contained. Some cells exhibited granule heterogeneity containing both HID‐positive and unstained granules. Spherical cores present in granules of mucous tubules below the upper laryngeal level occasionally appeared bizonal and invariably lacked reactivity demonstrative of complex carbohydrate. Mucous duct cell granules stained heavily with the PA‐TCH‐SP and DI methods and reacted infrequently with the HID procedure and were considered generally to contain sialylated glycoprotein, and occasionally to form sulfated glycoprotein. The three carbohydrate stains distinguished a heavily and a moderately reactive zone in the cortex outside the monophasic or biphasic, carbohydrate‐free cores in granules of some mucous duct cells.

Biological fate of a representative lipophilic metal compound (ferrocene) deposited by inhalation in the respiratory tract of rats

Rats were exposed by the nose-only route to ferrocene vapor labeled with 59 Fe and tritium. Serial sacrifices were performed up to 117 days following exposure. Over 75% of the tritium label was excreted within the firt day but the 59Fe label largely remained in the bronchopulmonary and nasopharyngeal regions over the duration of the experiment.

Deposition and clearance of labeled cigarette smoke particles in rat respiratory and digestive tract.

In this investigation 160 8-wk-old Sprague-Dawley rats inhaled smoke from 14C-labeled cigarettes in a Hamburg II smoking machine. The research cigarettes were labeled with [16,17-14C]dotriacontane. Eighty of the rats were acclimatized to smoke from nonlabeled research cigarettes for 21 d before inhaling labeled cigarette smoke. The investigation was divided into four experiments. In experiment I all rats were killed immediately after exposure to the 14C-labeled smoke from 30 cigarettes (10 muCi per cigarette) and the organs of the respiratory and digestive tracts were measured for 14C activity. These animals showed high activity in the apex nasi, fundus nasi, and larynx. The highest activity was found in the lobus dexter caudalis and the lobus sinister of the lung. The lungs contained four-fifths of the condensate inhaled into the respiratory tract. In experiment II three animals were killed immediately after smoking, three after 6 h, and four after 24 h. No activity was found after 6 h in apex, fundus nasi, larynx, and trachea. The lungs showed no clearance at all. The activity in the digestive tract was highest in the stomach and the esophagus immediately after cessation of smoking. These values decreased rapidly after 6 h. In experiment III the animals were killed after 7, 21, and 42 d. Clearance from the upper respiratory tract was fast, whereas clearance from the lungs was slow. Clearance from all lung lobes was faster in the nonacclimatized animals. In experiment IV the rats inhaled the smoke from 14C-labeled cigarettes (2 muCi per cigarette) on 5 successive days. The animals were killed 7, 14, and 21 d after the last smoke inhalation. Clearance from the lungs was slower in acclimatized and non-acclimatized animals than in experiment III.

Cigarette smoke induced pathology of the rat respiratory tract: A comparison of the effects of the particulate and vapour phases

Changes in the rat respiratory tract produced by a 12-week exposure to the particulate or vapour phases of cigarette smoke are described and compared with the changes produced by combined exposure to both phases. The most extensive change in the upper respiratory tract was a pronounced squamous metaplasis of the laryngeal epithelium, along with extensive deciliation and squame cell production. In the lung, smoke exposure produced marked increases in the numbers of bronchial goblet cells and intra-alveolar brown-gold macrophages. None of the above changes could be directly attributed to exposure to vapour phase alone, and in many cases the lesions produced by whole smoke and by carbon filtered smoke were directly comparable. For lesions to occur in some ciliated areas of the tract both phases of the smoke were required.

Mycoplasma-induced hydrocephalus in rats and hamsters.

Mycoplasma pulmonis, a pathogen of the respiratory tract in rats, was inoculated intracerebrally into neonate rats and hamsters to determine if it would induce lesions in the ependyma. Hydrocephalus was induced in 116 of 120 rats and in 23 of 28 hamsters. The severity of hydrocephalus was greater in the rats than in the hamsters. Hydrocephalus induction occurred only subsequent to inoculation of viable M. pulmonis. At 2 weeks of age, rats became refractory to induction of hydrocephalus. Light microscopy indicated that the hydrocephalus was communicating without an inflammatory response in the ventricles and meninges. Preliminary electron microscopy revealed that amorphous material covered portions of the ependymal surface and that cilia were sometimes matted together. It was suggested that the hydrocephalus was due to ciliary dysfunction or to an imbalance of cerebrospinal fluid secretion and absorption. This M. pulmonis-induced hydrocephalus may be a useful model for elucidating the pathogenesis of certain types of congenital hydrocephalus in humans.

A scanning electron microscopic study of the extrapulmonary respiratory tract

AbstractScanning electron microscopy, sometimes supplemented with transmission electron microscopy, was used to study the ultrastructural morphology of the extrapulmonary respiratory tract. Material for observation was taken from male rat respiratory tracts which were fixed in situ and critical point‐dried. Goblet cells, brush cells, potential ciliated cells, ciliated cells, cornified vestibule cells and the olfactory mucosa could be distinguished by their characteristic surface morphologies. The distribution of these various cell types throughout the extrapulmonary respiratory tract is described. Transmission electron microscopy of material treated with ruthenium red reveals that a polyanionic surface layer coats all cilia, microvilli and the intervening cell surfaces on all cell types found in the nasal cavities, trachea and extrapulmonary bronchi.

Effects of vitamin A on 3-methylcholanthrene-induced squamous metaplasias and early tumors in the respiratory tract of rats.

Effects of vitamin A on 3-methylcholanthrene-induced squamous metaplasias and early tumors in the respiratory tract of rats.

Mammalian ciliated respiratory epithelium; studies with particular reference to effects of menthol, nicotine, and smoke of mentholated and nonmentholated cigarettes.

THE PRESENT study was undertaken to determine the effects of menthol, nicotine, and the smoke of mentholated and nonmentholated cigarettes on excised mammalian respiratory epithelium from humans, rabbits, and rats. Previous studies on the effects of menthol on ciliated epithelium and on the respiratory tract have given equivocal findings. Proetz 1 reported that a 1% solution of menthol in liquid petrolatum had no effect on the ciliary activity of excised tissue immersed in it for 84 minutes. Similarly, Haggard and Greenberg 2 could find no toxic or irritant action of menthol in concentrations contained in the smoke of mentholated cigarettes on the respiratory tract of rats. Mendenhall and Shreeve, 8 however, reported that smoke solutions from cigarettes produced a depression in the ciliary rate of sections of calf's trachea and that smoke solutions from mentholated cigarettes caused a greater decrease in rate than did those from nonmentholated cigarettes. Further, Fox