Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.3.1.21 (CPT)
4,580 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cystic fibrosis (CF) is characterized by abnormal epithelial Cl- conductance (GCl). In vitro studies that have shown that cAMP regulation is an intrinsic property of the CF-affected GCl(CF-GCl) have been carried out previously on cultured secretory cells and on nonepithelial cells. Even though GCl in absorption is defective in CF, a clear demonstration of cAMP regulation of CF-GCl in a purely absorptive tissue is lacking. We studied the cAMP regulation of CF-GCl in the microperfused intact human reabsorptive sweat duct. About 40% of the ducts responded to cAMP (responsive) while the remainder of the ducts did not. In responsive ducts, cAMP-elevating agents: beta-adrenergic agonist isoproterenol (IPR), CPT-cAMP, forskolin, theophylline or IBMX increased Gt by about 2.3-fold (n = no. of ducts = 8). Removal of media Cl-, but not amiloride pretreatment (in the lumen), abolished the cAMP response, indicating exclusive activation of GCl. cAMP activated both apical and basolateral GCl. cAMP hyperpolarized gluconate: Cl- (lumen:bath) transepithelial bionic potentials (delta Vt = -20.3 +/- 5.2 mV, mean +/- SE, n = 9) and transepithelial 3: 1 luminal NaCl dilution diffusion potentials (delta Vt = -8.8 +/- 2.9 mV, n = 5). cAMP activated basolateral GCl as indicated by increased bi-ionic (gluconate:Cl-, bath:lumen) diffusion potentials (by about 12 mV). The voltage divider ratio in symmetric NaCl solutions increased by 60%. Compared to responsive ducts, nonresponsive ducts were characterized by smaller spontaneous transepithelial potentials in symmetrical Ringer's solution (Vt = -6.9 +/- 0.8 mV, n = 24, nonresponsive vs. -19.4 +/- 1.8 mV, n = 22, responsive ducts) but larger bi-ionic potentials (-94 +/- 6 mV, n = 35, nonresponsive vs. -65 +/- 5 mV, n = 17, responsive ducts) and dilution diffusion potentials (-40 +/- 5 mV, n = 11, nonresponsive vs. -29 +/- 3 mV, n = 7, responsive ducts). These results are consistent with an inherently (prestimulus) maximal activation of GCl in nonresponsive ducts and submaximal activation of GCl in responsive ducts. We conclude that cAMP activates CF-GCl which is expressed and abnormal in both apical and basal membranes of this absorptive epithelium in CF.
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PMID:cAMP activation of CF-affected Cl- conductance in both cell membranes of an absorptive epithelium. 128 85

We studied the developmental expression of the cystic fibrosis (CF) gene in human lung tissue from normal and CF-affected fetuses. Two unrelated CF fetuses, both homozygous for the delta F508 deletion, were examined. Cystic fibrosis transmembrane conductance regulator (CFTR) mRNA was present in second-trimester CF lung and in first- and second-trimester normal lung as assessed by amplification of reverse transcribed total RNA with the use of the polymerase chain reaction. CFTR protein was identified by immunoprecipitation in normal second-trimester fetal lung explants. To evaluate possible functional consequences of CF in the fetus, lung tissue explants were grown in submersion organ culture. By light and electron microscopy, the CF fetal lung explants appeared normal. When explants from normal fetal lung were exposed to 8-(4-chlorophenylthio) adenosine 3',-5'cyclic monophosphate (CPT-cAMP), and 3-isobutyl-1-methylxanthine (IBMX) for 24 h, the intraluminal fluid content increased, as assessed by a 40 +/- 4% increase in cross-sectional diameter. In contrast, identically treated CF explants showed no significant change in explant diameter (3 +/- 1.6%). The transepithelial potential (psi t) across fetal lung explants was measured with microelectrodes. In normal second-trimester explants, CPT-cAMP and IBMX caused hyperpolarization of psi t (-0.93 +/- 14 mV to -4.3 +/- 1.2 mV); in contrast, CF fetal lung explants showed no significant change in psi t with CPT-cAMP and IBMX (-0.84 +/- 0.07 mV to -1.21 +/- 0.26 mV). This study confirms the presence of CFTR mRNA and protein in human fetal lung and suggests that although the CF fetal lung appears normal morphologically, there is a defect in cAMP-mediated fluid secretion in the lung of the CF fetus.
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PMID:Expression of CFTR and presence of cAMP-mediated fluid secretion in human fetal lung. 137 70

Since December 1985, we have performed 38 transplantations: cardiac (CT) n: 31, cardiopulmonary (CPT) n: 1, or bipulmonary (BPT) n: 6. There were 31 male and 7 female patients, aged 7 to 62, mean 46. In the cardiac group, the cardiomyopathy was primitive in 13, ischemic in 16, valvular in 2. Five patients had undergone one or more previous operations. Three patients had a biventricular assist device (1,6 and 7 days before transplant) for acute cardiac failure. The indication of CPT or BPT was pulmonary artery hypertension (1), silicosis (1), cystic fibrosis (4). There were 4 post-operative deaths in the CT group (12.9%); failure of graft, low cardiac output, pulmonary artery hypertension by multiple pulmonary thrombosis, and 2 deaths in the CPT and BPT groups (28%). The mean post-operative hospital stay was one month. All patients with CT were treated by an initial maintenance bitherapy protocol (cyclosporine, steroids) and observed by myocardial biopsies and echocardiograms. In 40 per cent of the patients, Azathioprine was subsequently added. The patients had 2.1 rejection episode/patient/year, either spontaneously reversed of treated medically. There were two late deaths (2 and 7 months) by refractory rejection. 78 per cent of the patients were alive one year after transplant. All survivors have recovered a normal life, some of them with full-time work.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Heart and heart-lung transplantation. 3 years' experience in Timone CHU (Marseilles 1985-1988)]. 210 56

The immediate effect of four different modes of treatment was assessed by lung function tests on 19 infants with cystic fibrosis (CF) during the first year of life. The regimens were applied in a randomized fashion and consisted of aerosol inhalation of salbutamol (n = 8; SAL), aerosol inhalation of N-acetyl cysteine (n = 5; AC), chest physiotherapy (n = 6; CPT), and combined treatment with aerosol inhalation of SAL and AC followed by CPT (n = 6; COMB). Pulmonary function was measured before and shortly after therapy with each mode of treatment. Thoracic gas volume (Vtg) and specific airway conductance (SGaw) were measured by an infant whole body plethysmograph, and forced expiratory flow at resting lung volume (VmaxFRC) was determined with a thoraco-abdominal squeeze jacket. There was no correlation between baseline lung function and changes in any parameter due to treatment. Overall group comparison showed that the combined therapy resulted in a significant improvement in lung function when compared to any of the three treatments applied separately. There was no significant change in lung volumes in any individual group, but SGaw and VmaxFRC showed a small but significant improvement following the COMB treatment when compared with AC or CPT.
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PMID:Immediate effect of various treatments on lung function in infants with cystic fibrosis. 268 64

Both the immediate and long-term effects of chest physical therapy administered by a parent were evaluated in eight children with cystic fibrosis. Spirometric and plethysmographic evaluations were performed pre-CPT and at 5 and 30 minutes post-CPT. The pre-CPT measurements after a three-week period with no CPT were compared with the values while receiving CPT on a regular twice daily basis. There was a significant decrease after three weeks without CPT for FVC (P less than 0.025), FEV1 (P less than 0.005), FEF25-75 (P less than 0.005), and Vmax60TLC (P less than 0.025). When the patients had been receiving CPT on a regular basis, the only immediate effect was an increase in PEFR after 30 minutes post-CPT (P less than 0.05). After three weeks without CPT, there were increases at 30 minutes post-CPI for FVC (P less than 0.005) and Vmax60TLC (P less than 0.05). These findings indicate that although there may be little immediate functional improvement when CPT is received on a regular basis, a three-week period without CPT leads to a worsening of the functional status, which is reversed with renewal of regular CPT.
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PMID:Immediate and long-term effects of chest physiotherapy in patients with cystic fibrosis. 662 13

Based on the observation (Bradbury et al. (1992) Am. J. Physiol. 262, C752-C759) that conditions known to activate the cystic fibrosis transmembrane regulator protein (CFTR) increase the rate of exocytosis and decrease the rate of endocytosis, it was proposed that activation of the CFTR may involved cAMP-dependent fusion of CFTR containing endosomes with the apical membrane. We have tested this hypothesis in two cell lines derived from epithelia that express defective chloride transport in cystic fibrosis (CF): the human colonic cell line, T84, and the tracheal cell line 9HTEo-. The dose-dependence of forskolin- and CPT-cAMP-induced inhibition of endocytosis were compared with the dose-dependence of chloride channel activation. Endocytosis was determined from the uptake of FITC-dextran, and assayed in purified endosomes. Chloride channel activity was measured from the rate of I-efflux. If the fusion hypothesis is correct: (1) concentrations of agonist that inhibit endocytosis should activate chloride channel activity, and (2) the relationship between endocytosis and channel activation should be similar for forskolin and CPT-cAMP. Results in both cell lines were inconsistent with these postulates, suggesting that either chloride channel activation and the inhibition of endocytosis are separate effects of cAMP, or that the increase in apical CFTR resulting from agonist-dependent inhibition of endosomal fusion is minimal.
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PMID:Activation of the cystic fibrosis transmembrane regulator by cyclic AMP is not correlated with inhibition of endocytosis. 752 69

Cystic fibrosis is an autosomal recessive disorder affecting chloride transport in pancreas, lung, and other tissues, which is caused by mutations in the cystic fibrosis transmembrane regulator (CFTR). The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX) stimulates 36Cl- efflux from pancreatic CFPAC-1 cells which bear the delta F508 genotype common to most cases of cystic fibrosis [Eidelman et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5562-5566]. By contrast, correction of the cystic fibrosis defect by retrovirus-mediated gene transfer renders the resulting CFPAC-PLJ-CFTR cells insensitive to CPX. We now report that CPX also activates chloride efflux from the CF tracheal epithelial cell line IB3-1 bearing a delta F508 allele, but not if the IB3-1 cells have been repaired by transfection of the wild-type CFTR gene. Similar results were obtained with recombinant NIH 3T3 cells, in which CPX activates 36Cl- efflux from cells expressing the CFTR (delta F508) gene product but not from 3T3 cells expressing the wild-type CFTR. In all three cell types expressing CFTR (delta F508), CPX was found to activate 36Cl- efflux in a dose-dependent manner over the concentration range of 1-30 nM and then gradually lose potency at higher CPX concentrations. Six CPX analogues, A1 receptor antagonists of affinity similar to that of CPX, were found to be much less effective than CPX at activating 36Cl- efflux from CFPAC-1 cells. These included 2-thio-CPX. CPT (8-cyclopentyl-1,3-dimethylxanthine),3,4-dehydro-CPX,3-F-CPX,3-1-CPX, and KW-3902 (8-noradamantyl-1,3-dipropylxanthine).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine selectively activates chloride efflux from human epithelial and mouse fibroblast cell lines expressing the cystic fibrosis transmembrane regulator delta F508 mutation. 754 76

Single rat epididymal cell studied under whole cell patch-clamp condition responded to 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (CPT-cAMP) (500 microM) and to ionomycin (1 microM) by an increase in whole cell conductance. A major part of the stimulated current was carried by Cl-, although a small part was due to nonselective cation current. After elimination of the cation current component by using impermeant cation, the cells revealed different Cl- conductance properties in response to adenosine 3',5'-cyclic monophosphate (cAMP) and ionomycin. The cAMP-stimulated Cl- conductance was independent of time and voltage and showed a linear current-voltage relationship. The anion permselectivity was NO3- > Br- > Cl- approximately I- >> SO(4)2-. The ionomycin-stimulated Cl- conductance showed marked time and voltage dependency. In contrast to the cAMP-induced anion permselectivity, the ionomycin-induced anion permselectivity was I- > Br- approximately NO3- > Cl- >> SO(4)2-. These results indicate that the epididymal epithelial cells exhibit different Cl- conductances sensitive to cAMP and Ca2+. The cAMP-activated conductance has properties resembling the type associated with the cystic fibrosis transmembrane conductance regulator found in cystic fibrosis-affected epithelia. This finding supports the notion that the epididymis is a cystic fibrosis epithelium.
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PMID:Properties of cAMP-dependent and Ca(2+)-dependent whole cell Cl- conductances in rat epididymal cells. 768 72

Human tracheal epithelial cells in primary culture respond to different receptor agonists with different peak intracellular calcium concentrations. From resting concentration 138 +/- 13 nM, bradykinin (0.1 microM) produces an increase to a maximum of 835 +/- 195 nM, histamine (10 microM) to 352 +/- 51 nM, and ATP (5-500 microM) to more than 1500 nM. Nine of 14 cultures also responded to isoproterenol (10 microM), though with a smaller increase, to 210 +/- 29 nM. A response was observed with isoproterenol, and epinephrine, but not norepinephrine, phenylephrine or methoxamine, was inhibited by propranolol but not phentolamine, and so this appeared to be a beta-adrenergic response. However, no response could be detected to adenosine, prostaglandin E2 or forskolin, agents that activate adenylate cyclase, or to permeant analogs of cAMP (CPT-cAMP or db-cAMP). The intracellular calcium response to isoproterenol did not follow either the time-course or the desensitization pattern of the cAMP response. Thus, this response to isoproterenol is not mediated by cAMP. No relation was demonstrated between cAMP production by other agonists and the response of intracellular calcium. Pretreatment with agents that increase cAMP did not affect the calcium responses to ATP or bradykinin. Thus, cAMP does not regulate intracellular calcium concentration in human tracheal epithelial cells. The variation in peak intracellular calcium responses to various agonists may be explained by the presence of multiple second messengers (other than cAMP), multiple intracellular pools of calcium, or cell heterogeneity. The agonists tested had the same relative potency in cells from patients with cystic fibrosis as in non-cystic fibrosis cells.
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PMID:cAMP does not regulate [Ca2+]i in human tracheal epithelial cells in primary culture. 787 56

Defective organelle acidification has been proposed as a unifying hypothesis to explain the pleiotropic cellular abnormalities associated with cystic fibrosis. To test whether cystic fibrosis transmembrane conductance regulator (CFTR) participates in trans-Golgi pH regulation, intraluminal trans-Golgi pH was measured in stably transfected Swiss 3T3 fibroblasts (expressing CFTR or DeltaF508-CFTR) and CFTR-expressing and nonexpressing epithelial cells. trans-Golgi pH was measured by ratio-imaging confocal microscopy using a liposome injection procedure to label the lumen of trans-Golgi with fluid phase fluorescein and rhodamine chromophores (Seksek, O., Biwersi, J., and Verkman, A. S.(1995) J. Biol. Chem. 270, 4967-4970). Selective labeling of trans-Golgi was confirmed by colocalization of the delivered fluid phase fluorophores with N-(6-[(7-nitrobenzo-2-oxa-1, 3-diazol-4-yl)amino]caproyl)-sphingosine. In unstimulated fibroblasts in HCO3--free buffer, trans- Golgi pH was 6.25 +/- 0.04 (mean +/- S.E.; n = 80, vector control), 6.30 +/- 0.03 (n = 74, CFTR) and 6.23 +/- 0.06 (n = 60, DeltaF508) (not significant). After stimulation of plasma membrane Cl- conductance by 8-(4-chlorophenylthio)-cAMP (CPT-cAMP), trans-Golgi pH was 6.42 +/- 0.07 (n = 22, control), 6.47 +/- 0.07 (n = 20, CFTR), and 6.35 +/- 0. 07 (n = 22, DeltaF508) (not significant). Similarly, significant pH differences were not found for control versus CFTR-expressing cells in 25 mM HCO3- buffer. In epithelial cells, which do not express CFTR, trans-Golgi pH was (in 25 mM HCO3-) 6.36 +/- 0.04 (n = 33) and 6.34 +/- 0.08 (n = 23, CPT-cAMP) in MDCK cells and 6.25 +/- 0.04 (n = 18) and 6.24 +/- 0.06 (n = 15, CPT-cAMP) in SK-MES-1 cells. In Calu-3 cells, which natively express CFTR, trans-Golgi pH was (in 25 mM HCO3-) 6.19 +/- 0.05 (n = 25) and 6.17 +/- 0.08 (n = 23, CPT-cAMP). To test whether CFTR expression affects pH in the endosomal compartment in HCO3- buffer, pH was measured by ratio imaging in individual endosomes labeled with fluorescein-rhodamine dextrans. Comparing control and CFTR-expressing fibroblasts, average endosome pH (range, 5.40-5.53 after 10 min; 4.79-4.89, 30 min) differed by <0.13 unit, both before and after cAMP stimulation. These results indicate that CFTR expression and activation do not influence pH in the trans-Golgi and endosomal compartments, providing direct evidence against the defective acidification hypothesis.
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PMID:Evidence against defective trans-Golgi acidification in cystic fibrosis. 866 58


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