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Biomedical subjects

J Iravani

Publications and source records attributed to J Iravani.

At least 19 recordsLinked to original sources
PubMed1979

Airway response to adrenergic agonists and antagonists in 3-day- to 2-year-old rats.

The response of the airways to adrenergic agonists and antagonists was studied in 3-day- to 2-year-old and bronchitic rats. The results showed that the alpha-adrenoceptors are not functional at birth but become so by 8 weeks. In contrast, the beta-adrenoceptor effects are demonstrable on the third day after birth. The mean decrease in airway luminal diameter after beta-adrenergic blockade was greater in bronchitic than in healthy animals and was interpreted to be due to the increased sensitivity of the beta-adrenoceptors in bronchitis.

Acetylcholine↗
PubMed1978

Tracheobronchial clearance in health and disease: with special reference to interciliary fluid.

Rats were exposed to influenza B virus for 2 hours. Mucociliary function in the isolated airway preparation of these animals was studied from the first day after exposure and at regular intervals for up to 190 days. Transmission electron microscopy (TEM) studies were done at times corresponding to the mucociliary function studies. TEM studies confirmed the results of the mucociliary function studies: pathological changes were first apparent three days after exposure and began in the distal bronchioles. The morphological studies further demonstrated that the infection progressed proximally to include the entire tracheobronchial tree by the 18th day. The alterations observed included an increase in the number of goblet cells, a decrease in the number of microvilli and a reduction in the amount of interciliary fluid. The last two changes were closely correlated with the severity of the infection. The abnormalities found in mucociliary function included hypersecretion of mucus, inactive and hypoactive zones, synchronization of cilia beating, and a sticking together of the cilia tips.

Animals↗
PubMed1978

Closing and opening pressures in the intrapulmonary airways of rats.

Pressures at which the peripheral airways (PA) and terminal bronchioles (TB), open and closed, were studied in rats' lungs in vitro. Airway luminal diameter was directly measured at diminishing transbronchial pressure (closing) and increasing transbronchial pressure (opening) by means of a stereomicroscope with a calibrated eyepiece. The PA and TB had internal diameters at 100 mm H2O ranging from 173 to 306 micrometer and 122 to 204 micrometer, respectively. Most of the airways closed suddenly in the pressure range between 75 and 5 mm H2O and only a few were still open at zero pressure. Closure began in the distal portion of the PA and mid-portion of the TB usually in a concentric manner. Terminal bronchioles and PA that initially were prepared at room temperature instead of at 0 degrees C often contained air at zero pressure and showed a decreased response to acetylcholine. Subthreshold concentrations of acetylcholine increased the critical closing pressure by more than 100%. The critical opening pressure was considerably higher than the corresponding closing pressure. It is proposed that bronchiolar closure depends on the tone of the airway smooth muscle, the elasticity of the airway wall and probably on the surface tension of the liquid lining the mucosal membrane.

Acetylcholine↗
PubMed1978

N-Acetylcysteine and mucociliary activity in mammalian airways.

The effect of N-acetylcysteine on mucus trasnport velocity (MV), ciliary beat frequency (CBF), mucus production (MP), mucus lysis and on the micro-morphology of the secretory cells was studied in mammalian airways. The results showed that: 1. MV increased in healthy rats and rabbits, as well as in bronchitic rats, after concentrations as low as 10(-14) g/ml. Depression of MV occurred first at 10(-6) and 10(-5) g/ml in healthy and bronchitic animals, respectively. 2. CBF was stimulated at concentrations between 10(-12) and 10(-10) g/ml and decreased at concentrations above 10(-8) g/ml. 3. MP increased by approximately 100% over control values. 4. Lysis of stagnant mucus was evident first at a concentration of 10(-11) g/ml after 15 min incubation. 5. TEM confirmed the increased activity of the mucus secreting cells and showed that no pathological changes occurred within the cell following incubation at 10(-7) g/ml for up to 150 min. The importance of these findings on the overall mucociliary function is discussed.

Acetylcysteine↗
PubMed1977

Protease-induced constriction in rats' bronchi.

A method is described which allows quantitative measurements of bronchomotor function in vitro in all parts of the tracheobronchial tree. With this method it was observed that chymotrypsin, trypsin and ficin elicted contraction in the intrapulmonary airways of rats. The response could be abolished or diminished by phentolamin and atropine. Physostigmine did not potentiate the response. It is concluded that chymotrypsin operates mainly through alpha-adrenoreceptors, whereas trypsin and ficin operate through both a alpha-adrenoreceptors and cholinoceptive receptors.

Airway Resistance↗
PubMed1977

Comparison of the effects of several selective B2-receptor agonists on bronchomotor function in vitro.

Three selective B2-adrenergic stimulants were studied for their effect on the resting tone and on reversing acetylcholine (ACh)-induced bronchoconstriction in the intrapulmonary airways of rats in vitro. Neither 1-(3,5-dihydroxyphenyl)-2-[(1-[4-hydroxybenzyl]-ethyl)-amino]-ethanol-hydrobromide (Fenoterol) nor 2-tert-butylamino-1-(3,5-dihydroxyphenyl)-ethanol-sulphate (Terbutaline) had an effect on the resting tone. 4-Amino-3,5-dichlor-alpha-[(tert-butylamino)-methyl1-benzylalcohol-hydrochloride (NAB 365) caused a significant increase in the bronchial luminal diameter from control in the resting state at concentraions above 10(-5) g/ml. Only NAB 365 was effective in reversing ACh-induced bronchoconstriction in concentrations above 10(-6) g/ml. Terbutaline and Fenoterol reversed the ACh-induced bronchoconstriction only after the alpha-receptors had been blocked by phentolamine (10(-5)-10(-4)g/ml).

Acetylcholine↗
PubMed1976

Adrenergic compounds and the respiratory tract. A physiological and electron-microscopical study.

Studies were undertaken to determine the effect of several adrenergic compounds on ciliary activity and on the micromorphology of the goblet cells and mucous glands. All the substances tested, L-adrenaline, d-L-ephedrine, N-isopropyl-noradrenaline and 1-(4-amino-3, 5-dichlorphenyl)-2-tert-butyl-aminoethanol-HCl increased ciliary activity, but have markedly different effects on goblet cells, mucous glands and on the quality of the produced mucus.

Animals↗
PubMed1975

Factors affecting ciliary beat frequency in the intrapulmonary airways of rats.

The influence of drugs on ciliary beat frequency in the intrapulmonary airways of rats was studied in vitro. Sympathomimetic drugs significantly increased the ciliary beat frequency. Acetylcholine, pilocarpine, aminophylline, prednisolone, potassium iodide, and ammonium chloride also caused cilioexcitation, though to a lesser degree. Phentolamine, 5-hydroxytryptamine, histamine, and acetylcysteine caused an apparent cilioinhibition. However, histamine in high doses also caused an incoordination of ciliary beat. Codeine and phenobarbital were slightly cilioexcitatory in low concentrations and ciliodepressive at higher concentrations.

Animals↗
PubMed1975

[Effects of drugs and environmental factors on ciliary movement (author's transl)].

The effects of a number of drugs, potassium and calcium ions, and air humidity on mucociliary function were studied in isolated preparations of rats bronchial tree. Adrenergic drugs increased the rate of ciliary beat significantly. Cilioexitation also occurred, though to a smaller degree, after application of acetylcholine, pilocarpine, aminophylline, prednisolone, KI and NH4C1. Serotonin, histamine, and acetylcystein did not change ciliary frequency to any significant degree; however, histamine in high concentrations caused ciliary incoordination. Codein and normetadon, nicotine and pentobarbital had a dose-dependent ciliodepressive effect. However, small concentrations of nicotine and pentobarbital were slightly stimulative. Methysergid and phentolamine were slightly ciliodepressive. Alterations of the concentrations of calcium and potassium ions in the nutritive solution influenced ciliary frequency but had no effect on other characteristic features of the ciliary movement. The ciliated epithelium of the bronchial tree could be irreversibly damaged by air having low relative humidity.

Acetylcholine↗
PubMed1975

Mucocililary activity in the respiratory tract as influenced by prostaglandin E.

Evidence is presented from in vitro experiments in over 1,100 animals that the long accepted hypothesis of a continuous tracheobronchial mucus blanket is untenable, since mucus is transported in the form of flakes, plaques and continuous streams. It is proposed that a liquid of low viscosity lies between the cilia and covers their tips. This liquid is either not transported or very slowly so. Mucus flakes and plaques are transported by the tips of the cilia over this interciliary liquid. Prostaglandin E1 (PGE1) in low concentrations caused lysis of stagnant flakes and plaques. In addition, it caused a marked increase in the quantity of the tracheobronchial fluid and no clear-cut effect on the rate of ciliary frequency. The possible involvement of adenyl cyclase in the response to PGE1 is discussed.

Animals↗