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J M Farley

Publications and source records attributed to J M Farley.

At least 19 recordsLinked to original sources
PubMed2001

Activation of phospholipase D in porcine tracheal smooth muscle: role of phosphatidylinositol 3-kinase and RhoA activation.

Muscarinic receptor agonists transiently activate phospholipase D in tracheal smooth muscle. Muscarinic activation of phospholipase D in this tissue is dependent on activation of protein kinase C and an unidentified pathway that is not protein kinase C dependent. Cholinergic agents have also been shown to activate phospholipase D by pathways linked to the small G protein, RhoA. This study explores the relationship between muscarinic activation of phophatidylinositol 3-kinase and activation of RhoA, and examines whether phospholipase D activation is dependent on either pathway in tracheal smooth muscle. Wortmannin or 2-(4-morphonyl)-8-phenyl-4H-1-benzopyran-4-one (LY-294002), putative specific inhibitors of phophatidylinositol 3-kinase, significantly inhibit acetylcholine-induced formation of phosphatidylethanol and also block acetylcholine-induced translocation of RhoA to the membrane. In previous experiments calphostin C, a protein kinase C inhibitor, partially inhibited both acetylcholine-induced and phorbol-12-myristate-13-acetate (PMA)-induced phosphatidylethanol formation. In the present study calphostin C did not block acetylcholine-induced RhoA translocation to the membrane. However, the Rho kinase inhibitor, N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide (Y-27632), significantly inhibited acetylcholine-induced phosphatidylethanol formation, but had no effect on activation of phospholipase D by PMA. Acetylcholine treatment also stimulated the phosphorylation of the 110-kDa subunit of phosphatidylinositol 3-kinase. Phosphorylation of phosphatidylinositol 3-kinase 110-kDa subunit could be blocked by wortmannin in a concentration-dependent manner, and acetylcholine-induced phosphatidylinositol 3-kinase activity was significantly inhibited by wortmannin. LY-294002 also inhibited acetylcholine-induced phosphorylation of 110-kDa subunit and activation of phosphatidylinositol 3-kinase. These results suggest that acetylcholine stimulation translocates RhoA to the membrane by a phosphatidylinositol 3-kinase-dependent mechanism and acetylcholine-induced phospholipase D stimulation is at least partly mediated via phosphatidylinositol 3-kinase, however, protein kinase C appears to activate phospholipase D independent of phosphatidylinositol 3-kinase or RhoA activation in porcine tracheal smooth muscle.

Acetylcholine↗
PubMed2001

Mycoplasma alligatoris sp. nov., from American alligators.

Mycoplasmas were isolated from multiple tissues of diseased American alligators (Alligator mississippiensis). This paper presents biochemical, serological and molecular genetic characterizations of a lethal pathogen of alligators for which the name Mycoplasma alligatoris sp. nov. is proposed. The type strain is A21JP2T (ATCC 700619T).

Alligators and Crocodiles↗
PubMed2001

Newcastle disease virus in double-crested cormorants in Alabama, Florida, and Mississippi.

In order to understand the epidemiology of Newcastle disease (ND) outbreaks in double-crested cormorants (Phalacrocorax auritus), a study was conducted on wintering migratory cormorants (P. a. auritus) in Alabama and Mississippi (USA) and non-migratory cormorants (P. a. floridanus) that breed in Florida (USA). Antibodies against ND virus were detected by the hemagglutination-inhibition method in sera from 86 of 183 (47%) migratory cormorants over-wintering in eight roosting sites in Alabama and Mississippi between November, 1997 and April, 1999. Titers ranged from 5 to 40. Antibody prevalences in sera collected from females in early winter (November and December) (26%) and late winter (February and March) (56%) were significantly different (P = 0.0007). None of 45 serum samples from 1- to 7-wk-old nestlings from 11 colonies in Florida during the 1997-98 and 1998-99 breeding seasons was positive. However, antibodies were detected in yolk samples from 98 of 126 (78%) eggs collected in these same colonies. Titers ranged from 4 to 256. The prevalence of antibodies in eggs collected from fresh-water colonies (63% prevalence, n = 30) and salt-water colonies (82% prevalence, n = 96) was significantly different (P = 0.041). ND virus was not isolated from tissues of 18 cormorants and cloacal and tracheal swabs from 202 cormorants collected in Alabama and Mississippi; virus was also not isolated from cloacal and tracheal swabs from 51 nestlings from Florida.

Alabama↗
PubMed2000

Lidocaine-induced alterations in agonist-induced ion transport of cultured swine tracheal submucosal gland cells.

It has been documented that topical administration of lidocaine can cause airway complications, although it is the most used local anesthetic for laryngotracheal anesthesia. Thus, in this study we investigated the local actions of lidocaine on basal and autonomic secretagogue-induced ion transport in cultured swine tracheal submucosal gland cells. Ion transport plays an important role in maintaining effective mucociliary clearance and pulmonary defense mechanisms. It was measured as short-circuit current (Isc) utilizing Ussing chamber methodology. Exposure of cultured gland cells to lidocaine evoked a transient response with an initial increase in Isc followed by a decrease. The increase in Isc induced by lidocaine (3 mM) was 8.0 +/- 1.5 microA/cm(2). The maximal increases in Isc induced by isoproterenol and acetylcholine were 9.4 +/- 0.6 and 38.3 +/- 2.3 microA/cm(2), respectively. However, lidocaine significantly decreased the isoproterenol-induced increases in Isc. Acetylcholine-induced responses were not changed by lidocaine. Atropine did not significantly affect lidocaine-evoked events in ion transport. These results suggest that lidocaine directly alters epithelial transport of ions and also inhibits the adrenergic stimulation of epithelial ion transport.

Acetylcholine↗
PubMed2000

Human neutrophil elastase releases two pools of mucinlike glycoconjugate from tracheal submucosal gland cells.

Neutrophil elastase can contribute to the pathogenesis of increased airway reactivity and excess mucus secretion in many pulmonary diseases. Ten nanomolar human neutrophil elastase (HNE) effectively empties airway serous cells, raising the question of why HNE is not equally effective at emptying mucous cells of their stored mucin because total release of mucin granules is not seen in postmortem examination of even the most severe disease. To better resolve the mucus secretagogue action of HNE, we measured secretion of mucinlike glycoconjugates (MGCs) released from freshly isolated swine tracheal submucosal gland cells in fractions of the superfusate acquired every 2 min. Six to fifty nanomolar HNE released a fixed quantity of MGCs at an increasing rate with increasing concentrations of enzyme, an action consistent with the release of cell surface mucinlike molecules. The polycation poly-L-lysine (1 microg/ml) released a similar transient of MGCs. A steady-state doubling of MGC rate of release was seen as long as 100 nM HNE was present, but this stimulus represented less than a 1% release of stored MGCs/min and was consistent with release of mucin vesicles from cell stores. Both actions of HNE were inhibited by the specific inhibitors L-680833 and DMP-777 but not by 30 microM erythromycin. Therefore, HNE release of MGCs from tracheal submucosal glands is limited by both the fixed quantity of the MGCs in the transient pool and by the small steady-state response to the higher concentrations of enzyme.

Animals↗
PubMed1999

Activation of protein kinase A increases phospholipase D activity and inhibits phospholipase D activation by acetylcholine in tracheal smooth muscle.

Increased cAMP by stimulation of adenylyl cyclase with forskolin or by beta-adrenoceptor activation with isoproterenol increased phospholipase D (PLD) activity in tracheal smooth muscle strips. PLD activity was measured by the accumulation of phosphatidylethanol. A linear increase in the concentration of phosphatidylethanol was observed over 20 min in muscle strips treated with either forskolin or isoproterenol. Cholinergic stimulation with acetylcholine (ACh), by contrast, caused a rapid increase in phosphatidylethanol followed by a slow decline in the concentration of phosphatidylethanol from 5 to 20 min in the continued presence of ACh. Concomitant treatment with ACh and either forskolin or isoproterenol eliminated the rapid increases in phosphatidylethanol associated with ACh treatment. The response to forskolin or isoproterenol was not influenced by ACh. Inhibition of protein kinase C with calphostin C or bisindolylmaleimide I had no effect on isoproterenol- or forskolin-stimulated PLD activity but inhibited ACh-activated PLD activity. Protein kinase A (PKA) inhibitors H-89 and KT5720 significantly decreased forskolin- and isoproterenol-mediated activation of PLD activity. PKA inhibition also eliminated inhibition of ACh-stimulated PLD activity by forskolin or isoproterenol. Activation of adenylyl cyclase by forskolin or by isoproterenol caused increased phosphorylation of phospholipase C-beta(2) isoform and reduced the formation of inositol phosphates after ACh stimulation of muscarinic receptors. These results suggest that increasing the concentration of cAMP activates PLD via activation of PKA and that the increased activity of PKA also inhibits cholinergic stimulation of PLD, in part at least by inhibiting the activation of phospholipase C by ACh.

Acetylcholine↗
PubMed1998

Effects of 8-bromo-cyclic GMP on membrane potential of single swine tracheal smooth muscle cells.

Cyclic GMP relaxes swine tracheal smooth muscle. Relaxation occurs because of decreases in intracellular calcium concentration ([Ca++]i) that are thought to occur through hyperpolarization which inhibits calcium influx. Activation of K+ channels has been suggested as the underlying mechanism for the hyperpolarization. In the present study, the effects of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP, a membrane-permeable analog of cyclic GMP) on acetylcholine (ACh)-induced increases in [Ca++]i were examined by laser scanning confocal microscopy in fluo 3-loaded single cells. Membrane potential and currents were measured by the perforated-configuration of patch-clamp method, 8-Bromo-cGMP (1 microM-0.1 mM) inhibited 0.1 microM ACh-induced oscillations in [Ca++]i in a concentration-dependent manner. Spontaneous changes in membrane potential were observed by the patch-clamp method. Acetylcholine (0.03 microM) did not affect the time-averaged mean potential. The spontaneous changes in membrane potential were reduced and the cells were depolarized by 0.1 microM ACh and to a greater degree by 1 microM ACh. This result is consistent with previous observations of ACh-induced depolarization in intact tissue. The application of 0.1 mM 8-Br-cGMP had no significant effects on spontaneous changes in membrane potential and did not induce changes in membrane potential in cells treated with 0.1 microM ACh. In voltage-clamped cells, ACh (0.1 microM) induced oscillations in calcium-activated K+ currents. 8-Bromo-cGMP (0.1 mM) inhibited these ACh-induced oscillations in currents, but had no significant effects on spontaneous changes in membrane current in unstimulated cells. These data indicate that 8-Br-cGMP inhibits ACh-induced increases in [Ca++]i by mechanisms other than regulation of membrane potential.

Acetylcholine↗
PubMed1997

Reduction in the bioelectric properties of swine tracheal submucosal gland cells in culture after daily short-term exposure to cocaine.

Chronic use of cocaine has been associated with respiratory complications. In this study, we investigated the effects of daily short-term cocaine exposure on epithelial bioelectric properties and chloride secretion in response to secretagogues in primary culture of swine tracheal submucosal gland cells grown on microporous inserts. Cell cultures exposed continuously to cocaine for 24 h or intermittently for 30 min daily for up to 3 consecutive days, resulted in a concentration-dependent reduction in transwell voltage and transepithelial resistance. Cocaine (300 microM) treatment for 24 h decreased the voltage and resistance by 87 and 75%, respectively. The voltage and resistance were also substantially decreased after 3 days of intermittent cocaine (10-30 microM) exposure. Cocaine exposure protocols used here did not enhance lactate dehydrogenase (LDH) release. Chloride secretion was measured as short-circuit current utilizing Ussing chamber methodology. Cocaine exposure did not change the decreases in short-circuit current caused by amiloride (10 microM), but reduced the increases in short-circuit current induced by acetylcholine and isoproterenol. After 3 days of intermittent cocaine (30 microM) exposure, the maximal acetylcholine and isoproterenol responses were reduced by 67 and 71%, respectively. Therefore, cocaine exposure continuously for 24 h or intermittently for 30 min daily for up to 3 days decreased basal transepithelial voltage as well as resistance and reduced the responses to cholinergic and beta-adrenoceptor agonists. These results suggest that alterations in epithelial function can occur even after daily transient cocaine exposure.

Acetylcholine↗
PubMed1997

Mucus glycoconjugate secretion in cool and hypertonic solutions.

For sensitive individuals, exercise-induced asthma is triggered by cold and dry air and is often accompanied by a productive cough. In this study, we determined whether cold solutions and/or solutions of increased tonicity directly caused an increase in glycoconjugate (GC) secretion. To test this, we used isolated swine tracheal submucosal gland cells (TSGCs) and measured the rate of GC secretion at 37 and 32 degrees C in isotonic solutions and in solutions made hypertonic by 30 mosM. TSGCs were isolated under conditions that minimized the rate of GC secretion and were perfused with medium 199 equilibrated with 5% CO2 to a pH of 7.4. A lectin-based assay was used to specifically detect GC present in each 2-min fraction of the perfusate. Basal secretion was 3.1-fold greater at 32 degrees C (n = 3) than at 37 degrees C (n = 4; P < 0.05). At 37 degrees C, increasing perfusate osmolarity by 30 mosM increased the average rate of secretion by 41 +/- 11% (n = 4; P < 0.05); return to isotonic perfusate caused a 4.5 +/- 1.8-fold transient increase in secretion (n = 4; P < 0.05) that was complete within 10 min. At 32 degrees C, changing tonicity of the perfusate had no significant effect but returning to isotonic perfusate caused a 2.3 +/- 0.7-fold transient increase in secretion (n = 3; P < 0.05). Thus key stimuli that trigger obstruction of airflow (cold and increased osmolarity) can also directly stimulate GC secretion in the airway. Such increased secretions may contribute to the productive cough observed in some individuals in response to cold air.

Animals↗
PubMed1997

Muscarinic receptors inhibit ATP-sensitive K+ channels in swine tracheal smooth muscle.

The patch-clamp technique was used to characterize a cromakalim-induced current and its regulation by muscarinic receptors in tracheal smooth muscle cells. Cromakalim (10 microM) activated a steady-state increase of 33-292 pA (91.2 +/- 8.8 pA, n = 43) in whole cell current, consistent with the activation of ATP-sensitive K+ (KATP) channels. Acetylcholine (10 nM-1 microM), added cumulatively, inhibited the cromakalim-induced current by 23.6 +/- 14.9 to 73.9 +/- 4.6%. This inhibition was blocked by pretreatment with atropine (1 microM). The cromakalim-induced current was also inhibited 83.0 +/- 8.3% by phorbol 12-myristate 13-acetate (100 nM, n = 6). The inhibition of the cromakalim-induced current by acetylcholine (1 microM) and phorbol 12-myristate 13-acetate (100 nM) was reduced to 27.3 +/- 3.1% (n = 10) and 32.8 +/- 7.8% (n = 3), respectively, in the presence of staurosporine (100 microM). We conclude that muscarinic receptor stimulation inhibits KATP channel activity through the activation of protein kinase C. These findings suggest that KATP channels may play a role in the regulation of membrane potential and contractility in airway smooth muscle.

Adenosine Triphosphate↗
PubMed1996

Cocaine inhibits chloride secretion by swine tracheal submucosal gland cells grown in culture.

Active ion transport by airway submucosal gland cells plays an important role in maintaining effective mucociliary clearance. Alterations in the clearance will affect normal airway functions. Nasal and airway mucosal surfaces are exposed to high concentrations of cocaine after snorting crystals or smoking the freebase form, causing respiratory complications. The actions of cocaine on airway gland cell ion transport were determined by measuring the basal electrical properties and ion transport activated by acetylcholine (ACh) and isoproterenol (ISO) in swine tracheal submucosal gland cells grown in culture. The cells were enzymatically isolated, purified on Percoll density gradients, and then grown on microporous inserts at an air interface. Chloride secretion was measured as short-circuit current (Isc) utilizing Ussing chamber methodology. Amiloride (10 microM) was added mucosally to block sodium reabsorption. The maximal changes in Isc (delta Isc) induced by ACh and ISO were 42.0 +/- 4.4 and 8.8 +/- 0.8 microA/cm2. Cocaine decreased basal Isc and the increase in Isc induced by ACh and ISO. The concentration-response relationships for ACh and ISO were shifted to the right by cocaine (1-3 mM) when applied serosally. The maximal increase in Isc induced by ISO was inhibited by serosal cocaine, but, the maximal response to ACh was not. Thus, cocaine inhibits ACh-induced increases in Isc by competitively blocking the receptor and the response to ISO by noncompetitive inhibition. Mucosal cocaine reduced the maximal response to ACh and ISO and also caused a rightward shift. We conclude that cocaine directly alters submucosal gland cell function by reducing the basal and stimulated ability to transport ions and fluid.

Acetylcholine↗
PubMed1996

Acetylcholine-induced chloride current oscillations in swine tracheal smooth muscle cells.

The activation of muscarinic receptors by acetylcholine (ACh) in tracheal smooth muscle cells induced Ca++ oscillations, measured as the activation of Ca(++)-dependent Cl- currents (Clca) at the K+ equilibrium potential. The currents were not abolished by replacement of external and internal K+ with Cs+ but decreased after reduction in internal Cl- concentration or extracellular application of niflumic acid, a Cl- channel blocker. The Clca oscillations were dependent on external Ca++ concentration ([Ca++]e). The mean current and frequency increased with increasing [Ca++]e, were enhanced by Bay K 8644 and were inhibited by verapamil, suggesting a role for voltage-operated Ca++ channels (VOC). Steady-state increases in Clca induced by 10(-6) M ACh could be converted to oscillations by reducing [Ca++]e or by buffering intracellular Ca++ with ethyleneglycolbis-N,N,N'-N'-tetraacetic acid (EGTA). Oscillations in Clca induced by 3 x 10(-8) and 10(-7) M ACh were more sensitive to EGTA than those induced by 10(-6) M ACh. Caffeine induced nonoscillatory, transient increases in Clca and reduced subsequent ACh-induced increases in Clca. The oscillatory patterns of Clca induced by ACh and the effects of modification of Ca++ influx were similar for oscillations in intracellular Ca++ concentration [Ca++]i as measured with confocal microfluorimetry. Thus, ACh-induced Clca oscillations reflect fluctuations in [Ca++]i that are consistent with initiation of Ca++ release from inositol-1,4,5-trisphosphate-(IP3)sensitive Ca++ stores. Maintenance of the oscillations requires Ca++ influx, in part through voltage-operated Ca++ channels.

Acetylcholine↗
PubMed1996

Frequency modulation of acetylcholine-induced oscillations in Ca++ and Ca(++)-activated Cl- current by cAMP in tracheal smooth muscle.

The effects of adenosine 3':5'-cyclic monophosphate (cAMP) on acetylcholine (ACh)-induced oscillations in intracellular calcium concentration ([Ca++]i) and Ca(++)-activated Cl- current (ClCa current) were determined in isolated tracheal smooth muscle cells. Whole-cell current was measured in individual smooth muscle cells with patch clamp methodology. At a holding potential of -80 mV, ACh (0.1 microM) elicits base line-separated oscillations in ClCa current which correlate with oscillations in [Ca++]i. The addition of the beta adrenoceptor agonist isoproterenol (ISO) (10 nM to 1 microM) in the continued presence of ACh caused a concentration-dependent decrease in the frequency of the oscillations in ClCa current with significant reductions in oscillation frequency of 21.4 and 81.5% in the presence of 0.01 and 0.1 microM ISO, respectively (P < .05). This effect was mimicked by both forskolin (FSK) (3 microM) and 3-isobutyl-1-methylxanthine (IBMX) (30 microM). ISO and forskolin also inhibited ACh-induced oscillations in [Ca++]i measured by confocal fluorescence microscopy in non-voltage-clamped cells loaded with the Ca(++)-sensitive dye, fluo3. The inhibition of ACh-induced oscillations in ClCa current by ISO was partially reversed by increasing extracellular Ca++. These data are consistent with previous observations that the frequency of ACh-induced oscillations in [Ca++]i and ClCa current is dependent on the concentration of extracellular Ca++ and the influx of Ca++ through a verapamil-sensitive pathway. Moreover, these results lend support to the hypothesis that beta adrenoceptors inhibit the ACh-induced increase in [Ca++]i through a cAMP-dependent mechanism that inhibits Ca++ influx and in independent of changes in membrane potential.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Depletion and refilling of acetylcholine- and caffeine-sensitive Ca++ stores in tracheal myocytes.

We have previously shown that acetylcholine (ACh) induces oscillations in Ca++ and Ca++-activated Cl- currents (Clca) in tracheal myocytes. These oscillations are initiated by Ca++ release from inositol 1,4,5-trisphosphate-sensitive Ca++ stores and maintained by Ca++ influx, in part, through voltage-operated Ca++ channels. In the current study whole-cell Clca was measured in isolated tracheal smooth muscle cells as an index of changes in intracellular Ca++ concentration. We demonstrate that ACh-sensitive Ca++ stores and caffeine-sensitive Ca++ stores and caffeine-sensitive Ca++ stores are functionally linked but are refilled through distinct pathways. Two pathways responsible for replenishing ACh-sensitive Ca++ stores were identified. Ca++ influx through verapamil-sensitive voltage-operated Ca++ channels and Ca++ uptake through cyclopiazonic acid-sensitive Ca++ pumps accounted for 80% of the response. The other 20% of the response was both cyclopiazonic acid- and verapamil-insensitive. In contrast, the refilling of caffeine-sensitive Ca++ stores was not inhibited by 10 microM cyclopiazonic acid or 10 microM verapamil, but was dependent on extracellular Ca++ concentration. However, 0.2 microM thapsigargin, another more potent Ca++ pump inhibitor, completely and irreversibly eliminated ACh-induced transient Clca, whereas it reduced caffeine-induced Clca by 57%. The differences in refilling mechanisms and the functional overlap of ACh- and caffeine-sensitive Ca++ pools suggest that multiple interactive Ca++ stores play an important role in the generation of Ca++ signals in airway smooth muscle cells.

Acetylcholine↗
PubMed1996

Acetylcholine-induced Ca++-dependent chloride current oscillations are mediated by inositol 1,4,5-trisphosphate in tracheal myocytes.

We demonstrated previously that acetylcholine (ACh) induces Ca++ oscillations in tracheal myocytes. These oscillations, as measured with fluo3-loaded cells and confocal microfluorimetry, correlated with Ca++-dependent Cl- current (Clca) oscillations measured by whole-cell voltage-clamp recording. In the current study, we investigated the role of inositol 1,4,5-trisphosphate (IP3) in ACh-induced oscillations in Ca++ and membrane currents. Both an IP3 receptor monoclonal antibody (5 micrograms/ml) and an IP3 receptor antagonist, heparin (5 mg/ml), directly introduced into the cells via the patch pipette, reduced or abolished oscillations in Clca induced by ACh. In addition, IP3 (1-100 microM) applied intracellularly, elicited concentration-dependent Clca oscillations that resembled those induced by ACh. Increasing external Ca++ concentration enhanced IP3-induced Clca oscillations, whereas verapamil (10 microM), a voltage-operated Ca++ channel blocker, attenuated IP3-induced Clca oscillations as well as both control and IP3-enhanced spontaneous transient outward currents. However, neither 5 microgram/ml IP3 receptor monoclonal antibody nor 5 mg/ml heparin altered the caffeine-induced transient Clca. Caffeine (10 mM) reversibly eliminated IP3-induced Clca oscillations as well as IP3-enhanced spontaneous transient outward currents, which indicates that caffeine releases Ca++ via a mechanism independent of the IP3 receptor. The findings are consistent with the hypothesis that ACh-induced Ca++ oscillations can arise and be sustained via IP3-induced Ca++ release pathways.

Acetylcholine↗
PubMed1992

Transient cholinergic glycoconjugate secretion from swine tracheal submucosal gland cells.

By inference, muscarinic stimulation of glycoconjugate release from tracheal submucosal gland cells appears to be a transient, nonequilibrium process (J. M. Farley and T. M. Dwyer, Life Sci. 48: 59-67, 1991). To directly characterize the release kinetics of glycoconjugate, we developed an enzyme-linked lectin assay (ELLA) of much improved precision and resolution. To collect secreted products with an improved time resolution, freshly isolated swine tracheal submucosal gland cells were continuously superfused with medium 199 at 37 degrees, buffered with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) and CO2 or bicarbonate; fractions were collected every 15 s to 2 min. A 30-s pulse of 30 nM acetylcholine (ACh) increased the rate of glycoconjugate release by 10- to 25-fold for 2-3 min. The peak response averaged 14.2 +/- 9.0 ng protein.ml-1.min-1. 4 million cells-1 or 3.6 +/- 2.3 fg.cell-1.min-1 for 30 nM ACh and 16.2 +/- 3.0 ng protein.ml-1.min-1 for 100 nM ACh. There was no significant glycoconjugate release following a 30-s pulse of either 10 nM or 1 microM ACh. A second pulse after 7 min had no measurable effect on glycoconjugate release but a full response was obtained after 30 min. A continuous superfusion begun 1 min following the 30-s pulse resulted in a greater release of glycoconjugate than the pulse alone, but the response was not sustained, falling to twice basal levels within 5 min. We conclude that a brief muscarinic stimulation causes a triggered release of mucus glycoprotein followed by a relative refractory period.

Acetylcholine↗