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P Verdugo

Publications and source records attributed to P Verdugo.

At least 37 records · Page 2Linked to original sources
PubMed1987

Molecular mechanism of mucin secretion: I. The role of intragranular charge shielding.

Mucus is an ubiquitous polymer hydrogel that functions as a protective coat on the surface of integument and mucosa of species ranging from simple animals (such as coelenterates) to mammals. The polymer matrix of mucus is made out of long-chain glycoproteins called mucins that are tangled together, forming a randomly woven, highly polyionic network (Lee et al., 1977; Verdugo et al., 1983). Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling. Their swelling kinetics is similar to the swelling of condensed artificial polymer gels (Verdugo, 1984; Tanaka and Fillmore, 1979). We had proposed that mucins must be condensed in the secretory granule and expand by hydration during or after exocytosis (Verdugo, 1984; Tam and Verdugo, 1981). However, the polyionic charges of mucins prevents condensation unless they (the mucins) are appropriately shielded. The present experiments were designed to assert the presence of an intragranular shielding cation and its role in secretion. Giant mucin granules of the slug (Ariolimax columbianus) are released intact from mucus-secreting cells of the slug's skin. They burst spontaneously outside the cell, forming, upon hydration, the typical slug mucus (Deyrup-Olsen et al., 1983). We report here that these granules contain from 2.5 to 3.6 moles calcium/kg dry material, and that calcium is released from the granules immediately before the burst that discharges their secretory product. Therefore, we propose that calcium functions as a shielding cation of polyionic mucins, and that the bursting discharge of mucins from secretory granules must result from the release of calcium from the intragranular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Molecular mechanism of product storage and release in mucin secretion. II. The role of extracellular Ca++.

Mucin-containing granules, produced by mammalian goblet cells in vitro, undergo massive post-exocytotic swelling (23). Their swelling kinetics are similar to the swelling of condensed artificial polymer gels (22). Earlier, we proposed that mucins are condensed in the secretory granule and expand by swelling during or after exocytosis (21). The swelling of mucus is affected by ionic influences, as it is governed by a Donnan equilibrium process (21). However, the effect of cations on the swelling of newly released mucins had not yet been investigated. Calcium has been found in high concentration inside secretory granules of mucin-secreting cells (18, 9, 25), and is also elevated in the mucus of cystic fibrosis patients (17). The present experiments were designed to study the effect of extracellular Ca++ concentration on the swelling kinetics of the newly released secretory product of respiratory goblet cells in vitro. The data show that extracellular Ca++, in concentrations similar to those found in the mucus of cystic fibrosis patients (2 to 4 mM) can produce a four-fold decrease in the diffusivity of the newly released mucin polymer network, resulting in a slow rate of swelling, and a mucus that remains thick for long periods of time. The present findings are in agreement with the Donnan equilibrium hypothesis for the regulation of mucus swelling and rheology (21), and bear important implications for the pathophysiology of cystic fibrosis.

Animals↗
PubMed1986

The oviductal cilia and Kartagener's syndrome.

Women who have Kartagener's syndrome (primary ciliary dyskinesia) may or may not be fertile. The bronchial mucociliary clearance is reduced markedly in most of these women; this has led investigators to the conclusion that the cilia in the respiratory tract are immotile, and that "beating cilia may have no indispensable role in the female reproductive tract." Yet motile cilia are considered by many workers to be essential for normal ovum transport. More recently, bizarre ciliary motion has been described in the respiratory cilia of Kartagener's women. Our hypothesis was that the dyskinetic ciliary activity (or immotility) would be the same in both the respiratory and reproductive tracts and thus explain the fertility (or lack of it) in Kartagener's women. This report shows an identical ultrastructure and absolute immotility of cilia in both the respiratory tract and reproductive tract of a woman with Kartagener's syndrome who has never conceived. From this concordance, we suggest that the fertility of Kartagener's women is explained by the dyskinetic motion of oviductal cilia, and that the ciliated endosalpinx is essential for human reproduction.

Adult↗
PubMed1984

Hydration kinetics of exocytosed mucins in cultured secretory cells of the rabbit trachea: a new model.

Experiments have been done to test the idea that mucins undergo postexocytotic swelling. Previous work led to the hypothesis that the glycoprotein network of the mucus gel is probably held together by entanglements and low energy bonds, rather than by interchain covalent bonding. Since glycoproteins and other proteins in the mucus are polyions, it was further proposed that mucus must be capable of swelling, with its swelling properties depending on the pH and ionic strength of the medium hydrating the mucus. Experiments using oestrous cervical mucus from cows as a model confirmed this prediction. Observations on tissue cultures of respiratory secretory cells reported here show that freshly secreted mucins also undergo swelling during and after exocytosis. This evidence supports the hypothesis that the rheological properties of mucus may be physiologically regulated by hydration via control of the transepithelial movement of water, ions and soluble proteins, rather than by variations in the degree of covalent cross-linking between glycoprotein chains as proposed earlier.

Animals↗
PubMed1983

Conformational structure of respiratory mucus studied by laser correlation spectroscopy.

Samples of respiratory mucus were obtained from the trachea of dogs and patients undergoing bronchoscopy. The samples were studied by laser correlation spectroscopy. The autocorrelation function of laser light scattered by both human and canine respiratory mucus was a single exponential in thick mucus or a double exponential in thin watery mucus. This finding suggests that, as in the case of uterine cervical mucus, the molecular structure of respiratory mucus is an ensemble of entangled, randomly-coiled glycoproteins forming a loose network of variable density rather than a covalently cross-linked molecular network as proposed in earlier studies.

Animals↗
PubMed1980

Ca2+-dependent hormonal stimulation of ciliary activity.

It has been demonstrated that calcium modulates ciliary activity in protozoa and also in epithelial cilia of the mussel gill. Changes in the frequency of ciliary beat in the oviduct of the salamander have also been associated with movement of Ca2 across the cell membrane. However, the control of ciliary activity in mammals is poorly understood and the function of calcium in mammalian cilia and its role in coupling hormonal effects to changes in ciliary activity have been only preliminarily investigated. The evidence presented here suggests that the stimulus-response coupling of the stimulating effect of prostaglandin E2 (PGE2) on ciliary activity of the rabbit oviduct is carried out by release of intracellular Ca2+.

Animals↗
PubMed1980

A stochastic model for oviductal egg transport.

A mathematical description of ovum transport based on Langevin's diffusion equation is presented. The proposed model is deduced from qualitative features of this phenomenon, not induced from numerical fitting of experimental data. We demonstrate that egg transport in the ampulla of the rabbit oviduct can be represented as a one-dimensional random walk in a field of external force. The application of the model to describe isthmic ovum and sperm transport on the basis of simple random walk process is also discussed. The present formulation identifies and characterizes the forces involved in the motions of the ovum and predicts specific alternatives for physiological regulation of egg transport in the oviduct.

Animals↗
PubMed1980

Hormonal control of oviductal ciliary activity: effect of prostaglandins.

Prostaglandins have been shown to exist in the walls of the oviduct and to effect strongly oviductal muscle contractions and egg transport. Our observations, using laser light-scattering spectroscopy, indicate that the "natural" prostaglandins F2 alpha, E1, and E2 can stimulate ciliary activity in cultures of ciliated epithelium of the rabbit oviduct. These findings suggest a new alternative to explain the effect of prostaglandins on oviductal egg transport.

Animals↗
PubMed1980

beta-Adrenergic stimulation of respiratory ciliary activity.

We investigated the effect of isoproterenol on ciliary activity using a mucus-free preparation of cultured ciliated cells of the rabbit trachea. The frequency of ciliary beating was monitored by dynamic laser-scattering spectroscopy. The results demonstrated that isoproterenol directly stimulates the activity of ciliated cells of the respiratory epithelium and that this effect is beta-adrenergic specific inasmuch as the observed stimulation can be blocked by propranolol.

Animals↗
PubMed1979

Laser light-scattering spectroscopy: preliminary results on bioassay of cystic fibrosis factor(s).

The effect of 7 cystic fibrosis sera and 4 normal sera was investigated in 37 cultures of ciliated epithelium of the rabbit trachea. Serum was introduced in the Rose culture chambers in a concentration of 10% by volume. The frequency of ciliary beat was monitored by laser light-scattering spectroscopy. The results show that the response of cilia to sera can be well characterized by laser light scattering. Our preliminary evidence suggests that an early increase in the frequency of ciliary beat, followed by rapid arrest of ciliary activity, is a sensitive and characteristic response produced by cystic fibrosis serum, and not by normal serum.

Biological Assay↗