Search PubMed⌕ Search

Biomedical subjects

C B Basbaum

Publications and source records attributed to C B Basbaum.

At least 55 records · Page 3Linked to original sources
PubMed1986

cAMP immunocytochemistry provides evidence for functional VIP receptors in trachea.

Vasoactive intestinal peptide (VIP), first isolated from porcine intestine (S. I. Said and V. Mutt, Science Wash. DC 169: 1217-1218, 1970), has been identified in postganglionic autonomic axons of many tissues. VIP has potent regulatory effects on the function of various cell types within these tissues, ranging from relaxation of smooth muscle to ion transport. Recently, VIP has been implicated in the regulation of mucus secretion in the respiratory tract, a process involving release of macromolecules from exocrine cells and transport of ions and water across the airway mucosa. However, because airway glands and mucosa both consist of mixed cell populations, it was unclear which specific cells contained VIP receptors and contributed to VIP-evoked responses. We identified these specific cells by using immunocytochemical techniques to monitor concentration changes in adenosine 3',5'-cyclic monophosphate (cAMP), the intracellular compound known to mediate VIP responses. Serous and mucous cells of ferret tracheal submucosal glands and ciliated and basal cells of dog tracheal mucosa all increased cAMP in response to VIP stimulation. We conclude that these cell types possess VIP receptors and thus participate in VIP-stimulated responses. In contrast, ferret tracheal epithelium and dog epithelial goblet cells showed little or no reactivity after VIP, and thus we believe that these cells lack VIP receptors.

Animals↗
PubMed1986

Neuropeptides degranulate serous cells of ferret tracheal glands.

To determine whether serous or mucous cells in tracheal submucosal glands respond to the neuropeptides substance P (SP) and vasoactive intestinal peptide (VIP), we studied the peptide-induced changes in gland cell morphology accompanying release of 35SO4-labeled macromolecules from tracheal explants of ferrets. Explants were labeled for 1 h in medium containing 35SO4 and washed for 3.5 additional hours. Base-line secretion in the absence of drugs declined between 1.5 and 3.5 h after the pulse. Between 2.5 and 3.5 h, the average percent change in counts per minute recovered per sample period was not significantly different from zero (P greater than 0.3; n = 6). Substance P (10(-5) M) and VIP (2 X 10(-6) M) added 4 h after labeling each increased greatly the release of 35SO4-labeled macromolecules (SP, 219%; VIP, 180%) above base line. Bethanechol, a muscarinic-cholinergic agonist (10(-5) M), increased secretion by an average of 142% above base line (each effect, P less than 0.05; n = 6 each). Light and electron microscopy of the control tissues showed glands with narrow lumens and numerous secretory granules. Glands treated with SP or VIP had enlarged lumens and the serous cells were markedly degranulated. These phenomena were documented by morphometry and suggest that SP and VIP cause secretion from glands at least partially by stimulating exocytosis from serous cells.

Animals↗
PubMed1986

Structural changes associated with fluid absorption by dog tracheal epithelium.

During fluid absorption induced by amphotericin B, the lateral intercellular spaces (LIS) of the dog tracheal epithelium were widely dilated as compared to untreated time controls. When fluid absorption was inhibited by ouabain, or by replacement of luminal Na by choline, amphotericin B failed to cause dilation of the LIS. These data suggest that, as in other epithelia, a significant amount of transepithelial fluid flow passes down the LIS, and that these spaces may provide the local osmotic compartment which is responsible for linking transepithelial fluid movement to active ion transport.

Absorption↗
PubMed1986

Regulation of airway secretory cells.

Inhaled particles are cleared from the airways by ciliary transport of a discontinuous mucous layer. The effectiveness of this process depends on the viscoelastic properties of the secretion, which in turn depend on the composition and interaction of the glycoprotein constituents. In human airways, two major cell types in the surface epithelium (goblet and ciliated) and two in the submucosal glands (serous and mucous) are known to contain mucin- and/or serum-type glycoproteins. This article summarizes current knowledge regarding the secretable products of each of these cell types and the conditions under which they are released into the airway lumen.

Animals↗
PubMed1985

Degradation of extracellular matrix by the trophoblastic cells of first-trimester human placentas.

First-trimester human placental villi were cultured on 3H-leucine-labeled extracellular matrices isolated from the PF HR9 and PYS-2 cell lines. Both cell lines produced an extracellular matrix that contained basement membrane-specific macromolecules, including type IV collagen, laminin and proteoglycan. Both matrices promoted outgrowth of cells from the villi which, according to morphological criteria, were identified as cytotrophoblastic cells. As the cells migrated from the attachment site, they caused a marked focal dissolution of the matrix which was accompanied by a concomitant release of 3H-labeled material into the media. Approximately half of this material chromatographed near the inclusion volume of Sephadex G-50, indicating that the labeled matrix components had been degraded. This phenomenon was dependent on the age of the placenta. Second-trimester placental villi also adhered to the matrix, but no areas of dissolution were formed and no significant amounts of radioactivity were released into the medium. These results suggest that culture of first-trimester human placental villi on extracellular matrices may be useful for the study of some of the early embryonic events leading to human implantation, during which the trophoblastic cells erode the uterine epithelium.

Cell Line↗
PubMed1985

Sodium-pump density of cells from dog tracheal mucosa.

Uptake of tritiated ouabain by cells isolated from dog tracheal epithelium showed two components: a saturable component with a Km of 5.1 X 10(-8) M and a maximal uptake of 8.3 X 10(5) molecules/cell and a nonsaturating component of uptake that was linear with concentration. Several criteria indicated that the saturable uptake component represented binding to the Na+-K+-ATPase. To estimate the average surface area per cell, a known number of cells were pelleted and weighed, and the average surface area was calculated, assuming the cells to be perfectly spherical. The validity of this assumption was confirmed by comparing the calculated surface areas of cells in isotonic and hypotonic media. From the values for maximal saturable uptake and average surface area, a pump density of approximately 2,400 sites/micron2 was calculated. Given that the apical membrane lacks Na pumps and accounts for only approximately 5% of the total surface area, this value corresponds to the pump density of the basolateral cell membrane. The pump densities of ciliated, goblet, and basal cells were compared by autoradiography. The three cell types had approximately the same density of pump sites.

Animals↗
PubMed1984

Regulation of secretion from serous and mucous cells in the trachea.

The physical properties of mucus and the efficiency of tracheal mucociliary clearance depend on maintenance of a balanced interaction among several epithelial cell types. Some of these cell types are specialized to perform ion and water transport, others to perform synthesis and secretion of macromolecules. Our studies have been aimed specifically at identifying the neural mechanisms regulating macromolecule secretion from two of these cell types, i.e. serous and mucous gland cells. Because these cells occur as part of a complex epithelium, it is difficult to monitor the properties and functions of each cell type individually. We have therefore relied principally on morphological methods, which can potentially focus on a single cell type within a heterogeneous tissue. Such studies, however, depend on the availability of visible markers (enzyme-labelled antibodies, radioligands, etc.), and many important aspects of gland cell function cannot be assessed morphologically. Two alternative approaches are therefore being developed: the isolation and segregation of gland cells according to type, and the production of monoclonal antibodies that recognize secretory products of individual cell types. These methods allow serous and mucous cells to be studied by biochemical as well as morphological methods.

Animals↗
PubMed1984

Monoclonal antibodies as probes for unique antigens in secretory cells of mixed exocrine organs.

In the past, it has been difficult to identify the secretory product and control mechanisms associated with individual cell types making up mixed exocrine organs. This report establishes the feasibility of using immunological methods to characterize both the biochemical constituents and regulatory mechanisms associated with secretory cells in the trachea. Monoclonal antibodies directed against components of tracheal mucus were produced by immunizing mice with dialyzed, desiccated secretions harvested from tracheal organ culture. An immunofluorescence assay revealed that of the total 337 hybridomas screened, 100 produced antibodies recognizing goblet cell granules; 64, gland cell granules; and 3, antigen confined to the ciliated apical surface of the epithelium. The tracheal goblet cell antibody described in this report was strongly cross-reactive with intestinal goblet cells, as well as with a subpopulation of submandibular gland cells, but not with cells of Brunner's glands or the ciliated cell apical membrane. The serous cell antibody was not cross-reactive with goblet, Brunner's gland, or submandibular cells, or the ciliated cell apical membrane. The antibody directed against the apical membrane of ciliated cells did not cross-react with gland or goblet cells or the apical membrane of epithelial cells in the duodenum. Monoclonal antibodies, therefore, represent probes by which products unique to specific cells or parts of cells in the trachea can be distinguished. The antibodies, when used in enzyme immunoassays, can be used to quantitatively monitor secretion by individual cell types under a variety of physiological and pathological conditions. They also provide the means for purification and characterization of cell-specific products by immunoaffinity chromatography.

Animals↗
PubMed1984

Localization of cAMP in dog and cat trachea: effects of beta-adrenergic agonists.

Adenosine 3',5'-cyclic monophosphate (cAMP) is believed to mediate the transport of ions, water, and mucous glycoproteins in the respiratory tract. Because chemical measurements of total tissue levels of cAMP may not always reflect changes in specific cell types, we adapted standard immunocytochemical methods to examine the cellular localization of cAMP in dog and cat tracheae. The beta-adrenergic agonists terbutaline and isoproterenol increased immunoreactive cAMP in ciliated epithelial cells of dog and cat tracheae and in both serous and mucous gland cells of cat tracheae. Epithelial goblet cells did not respond to beta-adrenergic agonists in either species. This study provides information about the location of beta-receptors on individual cells in the trachea that is not available from chemical assays of either cAMP or beta-receptors in these tissues. Our results support the hypothesis that secretory functions in both serous and mucous submucosal gland cells and ciliated epithelial cells, but not goblet cells, may involve cyclic AMP-dependent mechanisms.

Animals↗
PubMed1984

Prostaglandins and intracellular cyclic AMP in respiratory secretory cells.

Prostaglandins are known to affect ion transport and mucus secretion in the trachea, and at least part of their effect is thought to be mediated by cyclic AMP. Because no prostaglandin receptor assay is currently available, we have used an immunocytochemical probe for the intracellular localization of cyclic AMP to identify those specific cell types in dog and cat trachea that respond to prostaglandins. Using tracheal explants similar to those used by other investigators for in vitro studies of ion transport and glycoprotein secretion, we examined the effect of endogenous and exogenous prostaglandins on immunoreactive cyclic AMP. Endogenous prostaglandins, which may be secreted in response to minor distortion of tissue membranes, stimulated immunoreactive cyclic AMP in ciliated epithelial cells and in both serous and mucous submucosal gland cells. This was not observed in tissues assayed 60 min after dissection, or dissected in the presence of indomethacin or of BW755C. Exogenous prostaglandin E1 increased cyclic AMP in these same cell types. We conclude that prostaglandins stimulate cyclic AMP in specific cell types in the trachea, and that endogenous prostaglandins play a major role in many in vitro preparations.

Animals↗
PubMed1984

Muscarinic receptors: evidence for a nonuniform distribution in tracheal smooth muscle and exocrine glands.

Muscarinic receptor distribution in smooth muscle, exocrine glands, and epithelium of the ferret trachea was determined using [3H]propylbenzilylcholine mustard ([3H]PrBCM) binding and autoradiography. Specific, atropine-sensitive [3H]PrBCM binding was quantified autoradiographically in the trachealis muscle (approximately 21 binding sites/microns2), surface epithelium (approximately 6 binding sites/microns2), and submucosal glands (approximately 5 binding sites/microns2). Serous and mucous cells in the glands did not differ in receptor density. Binding sites on gland and epithelial cells were associated with basolateral membranes. In the trachealis muscle, a gradient in receptor density was observed, with outer layers of muscle containing 3 to 10 times more receptors per unit area than inner layers. Receptor distribution in both glands and muscle paralleled the distribution of cholinergic axons. However, at the light microscope level, there was no evidence for the presence of receptor "hot spots" related to the position of individual axons. The parallelism in the distribution of axons and receptors suggests the possibility of neural control of the genesis and/or maintenance of receptor distribution in these tissues.

Animals↗
PubMed1983

Transmission in airway ganglia of ferrets: inhibition by norepinephrine.

We examined the possibility that norepinephrine inhibits transmission in parasympathetic ganglia of the ferret trachea. We impaled ganglion cells on recording microelectrodes and evoked postsynaptic action potentials by stimulating fiber tracts entering the ganglion. When norepinephrine was added to the recording bath, the action potentials were blocked. Phentolamine reversed this block. These results indicate that, by activating alpha-receptors, norepinephrine inhibits transmission in airway ganglia.

Animals↗
PubMed1983

Pulmonary alpha-adrenoceptors: autoradiographic localization using [3H]prazosin.

We determined the distribution of pulmonary alpha-adrenoceptors by autoradiographic localisation of [3H]prazosin binding to frozen sections of ferret lung. Specific binding of [3H]prazosin to lung sections was saturable and of high affinity (KD = 0.44 +/- 0.55 nM; mean +/- S.E., n = 5), with a specificity indicating binding to alpha 1-receptors. Autoradiographic showed that alpha 1-receptors were present in highest density in vascular smooth muscle (small vessels greater than large vessels), and were also present in airway submucosal glands and epithelium. There was also scanty labelling of alveolar walls which may be to contractile interstitial cells (Kapanci cells). Although smooth muscle of bronchi showed little labelling, surprisingly that of bronchioles was heavily labelled. The high density of alpha-receptors in small airways may be relevant to asthma in which alpha-adrenergic responses are activated. This method offers a means by which autonomic receptors of small airways may be investigated without the confusing contribution of other contractile elements and larger airways.

Animals↗
PubMed1983

Localization and release of lysozyme from ferret trachea: effects of adrenergic and cholinergic drugs.

Lysozyme is a bacteriolytic enzyme found in respiratory tract fluid. In this study, immunocytochemistry was used to determine the cells of origin of tracheal lysozyme in the ferret. Lysozyme was found in secretory granules of serous but not mucous cells in the submucosal glands, and was absent from the surface epithelium, cartilage, and connective tissue. The exclusive presence of lysozyme in serous gland cells renders it useful as a biochemical marker of that cell type. Measurements of lysozyme assayed from the incubating medium indicated that bethanechol stimulated lysozyme release by 260 +/- 80.9% (mean +/- SE), phenylephrine by 80 +/- 16.4%, and terbutaline by 25 +/- 10.2%. Electron-microscopic and immunocytochemical analysis of incubated tissues revealed loss of serous granules and lysozyme immunoreactivity in response to the drugs. Atropine, propranolol, and phentolamine blocked the stimulatory effects of bethanechol, terbutaline, and phenylephrine, respectively. These findings establish the usefulness of lysozyme as a serous-cell marker and demonstrate that secretory responses of different magnitude are evoked by equimolar concentrations of alpha- and beta-adrenergic and cholinergic drugs.

Animals↗
PubMed1983

Autoradiographic localization of autonomic receptors in airway smooth muscle. Marked differences between large and small airways.

Autoradiographic methods were used to determine the distribution of autonomic receptors in airway smooth muscle of ferret from trachea to terminal bronchioles; [3H]dihydroalprenolol, [3H]prazosin, and [3H]quinuclidinyl benzilate were used to label beta-adrenergic, alpha-adrenergic, and muscarinic receptors, respectively, using experimental conditions that gave maximal specific receptor binding. Marked differences were found in the longitudinal distribution of each receptor and in distribution of the various receptors in each caliber airway. Beta-receptors were present in high density throughout the airways, with the highest density in bronchioles. Alpha-receptors were sparse in large airways, but numerous in small bronchioles, whereas cholinergic receptors were numerous in bronchial smooth muscle, sparse in proximal bronchioles, and almost absent from distal bronchioles. This method may be useful in studying alterations of autonomic receptors distribution in small and large airways after experimental manipulation and in disease.

Animals↗
PubMed1983

Mapping of adrenergic receptors in the trachea by autoradiography.

We investigated the distribution of adrenergic receptors in ferret trachea using autoradiography. [3H]Dihydroalprenolol, used to identify beta-adrenoceptors, revealed a high density of specific binding sites over surface epithelium and submucosal glands, with less labelling of smooth muscle. [3H]prazosin labelling showed that alpha 1-receptors were numerous in glands and epithelium, but sparse in smooth muscle. Comparison of adrenergic receptor densities in tracheal sections from the same animals showed a rank order for submucosal glands of alpha 1 greater than beta, for epithelium beta greater than alpha 1 and for smooth muscle beta greater than alpha 1. Within the submucosal glands, alpha 1- and beta-adrenergic receptors were differentially distributed, with alpha 1-receptors being significantly more numerous over serous than mucous cells and beta receptors being significantly more numerous over mucous than serous cells. This technique provides insight into adrenergic regulation of airway function and should be useful in investigations of how relative receptor densities may be altered in disease.

Animals↗
PubMed1982

Muscarinic receptors in lung and trachea: autoradiographic localization using [3H]quinuclidinyl benzilate.

[3H]Quinuclidinyl benzilate binding to slide-mounted frozen sections of ferret lung was of high affinity (KD 63 +/- 14 pM, mean +/- S.E., n = 4), and characteristic of interaction with muscarinic cholinergic receptors. Light microscopic autoradiography showed muscarinic receptors to be localized predominantly to smooth muscle of trachea and intrapulmonary cartilaginous airways, and to submucosal glands. There was much less labelling of bronchiolar smooth muscle, airway epithelium and vascular smooth muscle and no labelling of alveoli. This distribution of receptors parallels that of cholinergic innervation.

Animals↗