[The pulmonary toxicity of e-cigarette vaping exposure and the benefits of air cleaner application].

To evaluate e-cigarette vaping-induced respiratory toxicity and the interventional effects of air cleaners. A randomized controlled trial study of toxic vaping by the respiratory tract were conducted at the Key Laboratory of Environmental Medical Engineering, Ministry of Education, the School of Public Health, Southeast University from January to December 2022. 8-week-old male C57BL/6JGpt mice selected with a random number table method were used to establish a vaping-exposure model at different periods (0 d, 3 d, 7 d or 14 d), or exposed to clean air as a control group. Mice were exposed to regular heated vaping (200 ℃) and high-temperature heated vaping (280 ℃). Total lung RNA was extracted from control and e-cigarette exposed mice for transcriptome sequencing analysis. Reactive Oxygen Species (ROS) generation and mitochondrial membrane potential (MMP) were detected by flow cytometry. Total superoxide dismutase (SOD) and superoxide (O2-) were evaluated using a microplate reader. Real-Time Quantitative PCR (RT-qPCR) was used to detect gene expression. Air filter and ionizer were used to intervene the toxicity of vaping. Data were expressed as (x¯±s), differences between multiple groups were compared using one-way or two-way ANOVA. The results showed that, RNA sequencing assays suggested that the differential genes between the control and vaping exposure groups were significantly enriched in the oxidative stress (Fold Enrichment=3.18) and mitochondrial oxidative phosphorylation (OXPHOS) (Fold Enrichment=5.74) pathways. Both types of heated vaping exposure caused significantly increased the score of alveolitis (F=10.8, P<0.001), increased endogenous ROS generation (F=16.8, P<0.001), decreased MMP (F=13.6, P<0.01), and gene expression of mitochondrial complex I dysfunction. The toxic effects of high-temperature heated vaping were stronger compared to regular heated vaping (F=2.9, P<0.05). The filter demonstrated better protective effects against vaping than the ionizer by reducing pulmonary alveolitis (F=7.4, P<0.01). Air cleaners could partially alleviate oxidative stress and mitochondrial dysfunction. In conclusion, this study demonstrate that vaping brings potential health risks. Air cleaners could partially reverse mitochondrial dysfunction, but cannot completely prevent the toxic effects, effective interventions remain to be investigated.

[Effects of paraquat on the proliferation of human neural stem cells via DNA methylation].

Objective: To investigate the effects of Paraquat on neural stem cell proliferation in vitro and explore the its mechanism based on DNA methylation pathway. Methods: Nestin, ß-tubulin III, and glial fibrillary acidic protein (GFAP) were detected by indirect immunofluorescence assay to evaluate self renewal and differentiation potentia of ReNcell CX human neural stem. The cells were treated with terminal concentrations of 0, 5, 25, 50, and 100µmol/L PQ for 24 hours, and the cells were induced by 50 µmol/L PQ for different time (6, 12, 24, 48 h). Cell viability was determined by MTT assay. The proliferation of neural stem cells was evaluated using Sox2/Brdu and Nestin/Brdu double immunofluorescence staining. The global DNA methylation level was assayed by MethyflashTM methylated DNA Quantification kit. The expression levels of Dnmts mRNA and protein were analyzed by quantitative reverse transcription polymerase chain reaction(qRT-PCR) and Western blot, respectively. Results: Immunofluorescence showed that nestin was primarily expressed in proliferative neural stem cell and peotein biomarkers (ß-tubulin III, GFAP) for neuron and astrocyte were expressed in differentiated cells. MTT assay showed PQ induced cell survival rate decrease in a time and dose dependent manner. Double immunfluorescence staining of cells showed colocalization of Sox2 and Brdu. The percentage of Brdu/Sox2 positive cells was significantly lower in the PQ-exposed (25, 50, 100µmol/L PQ treatment) groups compared to control (P<0.05); Meanwhile, The percentage of Brdu/Nestin positive cells was also significantly lower in the PQ-exposed(50,100µmol/L PQ treatment) groups compared to control (P<0.05). The results of global DNA methylation revealed a significant decrease in PQ-exposed groups (P<0.05). Western blot showed that compared with control group, the protein and mRNA levels of Dnmt1, Dnmt3a in PQ-exposed group were significantly decreased (P<0.05), but there was a significant increase in expression level of Dnmt3b in 50, 100 µmol/L PQ-treated group(P<0.05). Conclusion: Paraquat could inhibite the proliferation of human neural stem cells through reducing the level of DNA methylation reaction by suppressing the protein expression and transcription of DNA methylated transferase(Dnmts).

Variations in Gnai2 and Rgs1 expression affect chemokine receptor signaling and the organization of secondary lymphoid organs.

Ligand bound chemoattractant receptors activate the heterotrimeric G-protein G(i) to stimulate downstream signaling pathways to properly position lymphocytes in lymphoid organs. Here, we show how variations in the expression of a chemokine receptor and in two components in the signaling pathway, Galpha(i2) and RGS1, affect the output fidelity of the signaling pathway. Examination of B cells from mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3 provided the basis for these results. Loss of a single allele of either Gnai2 or Rgs1 affected CCL19 triggered chemotaxis, whereas the loss of a single allele of Ccr7, which encodes the cognate CCL19 receptor, had little effect. Emphasizing the importance of Gnai2, B cells lacking Gnai3 expression responded to chemokines better than did wild-type B cells. At an organismal level, variations in Rgs1 and Gnai2 expression affected marginal zone B-cell development, splenic architecture, lymphoid follicle size, and germinal center morphology. Gnai2 expression was also needed for the proper alignment of MOMA-1(+) macrophages and MAdCAM-1(+) endothelial cells along marginal zone sinuses in the spleen. These data indicate that chemoattractant receptors, heterotrimeric G-proteins, and RGS protein expression levels have a complex interrelationship that affects the responses to chemoattractant exposure.

Risk factors for neonatal nosocomial enteric infection and the effect of intervention with BIFICO.

OBJECTIVE: This study aims to investigate the risk factors for neonatal nosocomial enteric infection (NNEI) and the effect of intervention with BIFICO. PATIENTS AND METHODS: Between May 2013 and June 2015, 215 neonates admitted to our institution were randomly divided into the study group and the control group, 47 for each group. Patients in the study group were treated for primary diseases combined with the oral admission of BIFICO, whereas patients in the control group were treated for primary disease alone. Statistical analysis was performed to obtain the occurrence of enteric infection and univariate, as well as multivariate analysis of clinical data, were performed to investigate the underlying risk factors. RESULTS: Univariate and multivariate analysis of variance showed that gestational age, birth weight, length of hospital stay, invasive procedures and underlying diseases were risk factors affecting NNEI. The occurrence of NNEI in the study group was significantly lower than that in the control group [17.02% (8/47) vs. 29.79% (14/47), X2 = 19.394, p = 0.004]. CONCLUSIONS: Preterm infant, low-birth-weight infant, length of hospital stay, invasive procedures and comorbidity are independent risk factors for NNEI. Prophylactic therapy with BIFICO can effectively decrease the occurrence of infections and can be widely used in clinical practice.

Effect of fluorophore linkage position of n-(9-anthroyloxy) fatty acids on probe distribution between coexisting gel and fluid phospholipid phases.

The quenching of probe fluorescence by spin-labeled phospholipid has been used to determine the distribution of a series of n-(9-anthroyloxy) fatty acids between coexisting gel and fluid liquid-crystal phases in multilamellar phospholipid vesicles. The phase distribution ratio in every case is found to favor the fluid lipid phase, but is much greater between fluid and Ca2+-induced gel than between fluid and thermal gel. For a given gel type, n-(9-anthroyloxy)stearic acids with n = 3, 6, 9 or 12 as well as 11-(9-anthroyloxy)undecanoic acid all exhibit similar behavior, favoring the fluid phase by about a factor of 4 over thermally-induced lipid gel phase and by 18 over Ca2+-induced gel phase. 16-(9-Anthroyloxy)palmitic acid, with the bulky probe at the terminus of the 16-carbon chain, favors the fluid phase less strongly, by a factor of 1.5 or 11 over thermally-induced or Ca2+-induced gel phase, respectively, indicating better packing of this probe in phospholipid gel phases.

Clinical features, survival rate, and prognostic factors in young adults with cystic fibrosis.

The medical records of 142 patients with cystic fibrosis were reviewed. The patient group included 78 males and 64 females; three patients were black. Periods of observation ranged from two to 25 years (mean, 14.5 years). The analysis focused on clinical evaluation at age 18 years and included information gained at an earlier age. Evaluation at age 18 years was based on Shwachman and Kulczycki's (S-K) scoring system, Brasfield chest roentgenographic scoring system, pulmonary function measurements, height-adjusted weight percentile, sputum bacteriologic results, number of hospitalizations for treatment of pulmonary infections prior to the age of 18 years, time of onset of clubbing, and frequency of complications. There were no significant differences between the sexes in clinical features. Median survival from the time of diagnosis to the conclusion of the study period (1955 to 1984) was 22 years for females and 25 years for males (NS). Median length of survival beyond the age of 18 years was eight years for females and 12 years for males (NS). Stepwise logistic regression and Cox regression analysis applied to 11 variables identified the S-K clinical score at 18 years of age as the best predictor of survival to the age of 23 years. The median durations of survival after the age of 18 years for patients with clinical scores of 30 to 49, 50 to 64, and 65 to 75 at age 18 were five, seven and a half, and 12 years, respectively (p less than 0.0001). Low clinical score, low weight percentile, and Pseudomonas cepacia colonization of the lower respiratory tract at the age of 18 years indicated a poor prognosis. On the other hand, high clinical score, good weight percentile, and colonization with Staphylococcus aureus alone were likely to be found in patients with mild disease and an increased likelihood of long-term survival with preserved pancreatic function.

Cooperative study comparing three methods of performing sweat tests to diagnose cystic fibrosis.

Directors of cystic fibrosis centers in the United States have noted an increasing number of patients with histories of either false-positive or false-negative sweat tests. These inaccuracies were attributed to the use of rapid test methods which avoided actually weighing the sweat collected. These rapid tests have inherent difficulties which, theoretically at least, could lead to mistaken diagnoses. To evaluate methods of performing the sweat test, the National Cystic Fibrosis Foundation organized a combined study comparing the older Quantitative pilocarpine iontophoretic test (QPIT) method of performing the test with two newer and more rapid methods, the Orion skin electrode, and the Medtherm conductivity apparatus. Five cystic fibrosis centers participated in the study. Although two centers obtained considerably more accurate results with the Orion and the Medtherm than did the other three centers, the combined results of the study indicate that these procedures can be considered to be little more than screening tests.

Evaluation of a paper-patch test for sweat chloride determination.

This article evaluates a recently developed qualitative sweat patch test (SPT). A battery-powered stimulator with polymer pad electrodes is used to stimulate sweating, followed by the application of a paper patch which collects the sweat and shows color change on sweat chloride levels above 40 to 50 mEq/l. Our data consist of 66 patients with cystic fibrosis, 75 control subjects, and 37 relatives of patients with cystic fibrosis, excluding 22 subjects (11%) with insufficient sweat. There were no false-negative results among 66 patients with cystic fibrosis, and in the control group, 71 of 75 subjects gave negative results and the other four gave positive results. Of the 37 relatives, eight gave positive results; all of the eight subjects are parents of patients with cystic fibrosis. Our results indicate that SPT is useful and reliable when there is sufficient sweat. This portable and simple patch test may serve as an excellent screening test for cystic fibrosis.

Evaluation fo recurrent respiratory tract infections.

We have outlined the appropriate study of patients with recurrent respiratory tract infections. A detailed history and a complete physical examination, together with a chest roentgenogram, will, in most instances, give clues to a possible diagnosis. Among the laboratory studies listed in Table 2, the easily available and relatively informative tests consist of routine hemoglobin, white blood cell and differential count, sputum and throat culture for bacteria isolation, screening pulmonary function tests. Most of the other laboratory tests (including sweat tests) and diagnostic procedures require experienced and trained personnel and special facilities and equipment that are available in pediatric pulmonary centers. Any patient suspected of having a complicated or serious pulmonary disease or a congenital anomaly that is correctable by surgery should be referred to a pediatric pulmonary center for a complete diagnostic evaluation. It is important that this be done as soon as possible so that early institution of appropriate therapy may lead to a cure of the pulmonary disorder.

The use of new antibiotic agents for chronic pulmonary disease.

Modern advances in the development of antimicrobial agents and in chemotherapy have made available potent aminoglycoside antibiotics, with more effective ones to come. Their effectiveness against P. aeruginosa is a great contribution to patients with cystic fibrosis and other chronic disorders. The development of carbenicillin has augmented the effectiveness of the aminoglycoside antibiotics. Ticarcillin is similar to carbenicillin and will play a similar role in antibiotic therapy. The cephalosporins serve as alternative agents principally for their antistaphylococcal activity. We are urgently in need of a potent antibiotic agent against P. aeruginosa that can be given by the oral route. The TMP-SMX combination is a potent chemotherapeutic agent that can be administered by the oral route. It is effective in the treatment of P. carinii pneumonia, which is very common owing to the extended survival of patients with leukemia and other malignancies or with allografts who are prone to develop infections with immunosuppressive therapy.

Respiratory complications of primary hypogammaglobulinemia.

The primary hypogammaglobulinemias, with onset of acute and recurrent bacterial infections in infancy and early childhood, consist of a heterogeneous group of largely genetically determined antibody deficiency states including that congenital sex-linked form, Bruton's agammaglobulinemia. Patients with panhypogammaglobulinemia require continuous gamma globulin therapy; in spite of this, they continue to develop infections of the upper and lower respiratory tract in the form of otitis media, mastoiditis, sinusitis, rhinitis, pharyngitis, tracheobranchitis, or pneumonia of a chronic and recurrent nature. The frequency and severity of these infections vary from patient to patient. These episodes all respond to antibiotic administration, often with a prolonged course. Many patients develop permanent pulmonary sequelae in the form of atelectasis, bronchiectasis, and pulmonary fibrosis. Most of these changes involve focal areas of the lower right middle and left lingular lobes. Occasionally, the patient may develop generalized bronchiectasis but without hilar lymphadenopathy. Management emphasizes early detection, early institution of gamma globulin treatment, and administration of appropriate antibiotic therapy at the earliest onset of infection. Good pulmonary toilet, nutritional care, emotional care, and a loving home environment are of utmost importance. These patients should be followed in a medical center with the joint effort of specialists in various disciplines.

n-Soliton solution of the modified nonlinear Schrödinger equation.

An n-soliton solution of the modified nonlinear Schrödinger equation is presented, and its relationship to the nonlinear Schrödinger equation is given.

Stimulation of aged human lung fibroblasts by extracellular ATP via suppression of arachidonate metabolism.

The mitogenic effect of extracellular ATP on IMR-90 human fibroblasts subjected to in vitro aging was studied. ATP stimulated DNA synthesis and cell proliferation in young cells as much as epidermal growth factor (EGF) or insulin, while it stimulated aged cells to a much greater extent than seen for any other growth factor tested. When combined with EGF or insulin, ATP restored the greatly reduced mitogenic responsiveness of aged cells nearly to the level noted for young cells. Addition of prostaglandin E2 or other agents that elevate cAMP levels resulted in inhibition of DNA synthesis stimulated by EGF or insulin. Furthermore, the basal release of arachidonic acid and prostaglandin E2 and the endogenous levels of cAMP rose during aging and became much greater than in young cells. All three of these changes were suppressed by extracellular ATP. ATP-dependent suppression of cAMP accumulation was pertussis toxin-sensitive. Protein kinase C down-regulation inhibited arachidonate metabolism and enhanced DNA synthesis stimulated by ATP. These studies suggest that ATP exerts its mitogenic effect, especially on aged IMR-90 cells, at least partially by suppression of arachidonate metabolism.

Extracellular ATP shows synergistic enhancement of DNA synthesis when combined with agents that are active in wound healing or as neurotransmitters.

The polypeptides PDGF, TGF alpha, and EGF have previously been shown by others to stimulate proliferation of fibroblasts and keratinocytes in the process of wound healing. Here we demonstrate that extracellular ATP, ADP or AMPPNP caused synergistic enhancement of DNA synthesis in 3T6 mouse fibroblasts and BALB/MK keratinocytes when combined with any of the above polypeptides. TGF beta showed synergistic stimulation with ATP in fibroblasts but it inhibited keratinocytes. ATP acted as a mitogen for NIE-115 neuroblastoma cultures. In 3T6 cells, ATP stimulated thymidine incorporation in combination with carbachol or norepinephrine. The effect of carbachol was sensitive to atropine. We suggest that extracellular ATP and ADP may play a physiological role in wound healing and as a mitogenic neurotransmitter in the nervous system.

Extracellular ATP and ADP stimulate proliferation of porcine aortic smooth muscle cells.

The mitogenic effect of extracellular ATP on porcine aortic smooth muscle cells (SMC) was examined. Stimulation of [3H]thymidine incorporation by ATP was dose-dependent; the maximal effect was obtained at 100 microM. ATP acted synergistically with insulin, IGF-1, EGF, PDGF, and various other mitogens. Incorporation of [3H]thymidine was correlated with the fraction of [3H]thymidine-labeled nuclei and changes in cell counts. The stimulation of proliferation was also determined by measurement of cellular DNA using bisbenzamide and by following the increase of mitochondrial dehydrogenase protein. The effect of ATP was not due to hydrolysis to adenosine, which shows synergism with ATP. ATP acted as a competence factor. The mitogenic effect of ATP, but not adenosine, was further increased by lysophosphatidate, phosphatidic acid, or norepinephrine. The inhibitor of adenosine deaminase, EHNA, stimulated the effect of adenosine but not ATP. The adenosine receptor antagonist theophylline depressed adenosine-induced mitogenesis. ADP and the non-hydrolyzable analogue adenosine 5'-[beta, gamma-imido]triphosphate (AMP-PNP) were equally mitogenic. Thus extracellular ATP stimulated mitogenesis of SMC via P2Y purinoceptors. The mechanism of ATP acting as a mitogen in SMC was further explored. Extracellular ATP stimulated the release of [3H]arachidonic acid (AA) and prostaglandin E2 (PGE2) into the medium, and enhanced cAMP accumulation in a dose-dependent fashion similar to ATP-induced [3H]thymidine incorporation. Inhibitors of the arachidonic acid metabolism pathway, quinacrine and indomethacin, partially inhibited the mitogenic effect of ATP but not of adenosine. Pertussis toxin inhibited ATP-stimulated DNA synthesis, AA release, PGE2 formation, and cAMP accumulation. Down-regulation of protein kinase C (PKC) by long-term exposure to phorbol dibutyrate (PDBu) partially prevented stimulation of DNA synthesis and activation of the AA pathway by ATP. The PKC inhibitor, staurosporine, antagonized mitogenesis stimulated by ATP. No synergistic effect was found when PDBu and ATP were added together. Therefore, a dual mechanism, including both arachidonic acid metabolism and PKC, is involved in ATP-mediated mitogenesis in SMC. In addition, ATP acted synergistically with angiotensin II, phospholipase C, serotonin, or carbachol to stimulate DNA synthesis. Finally, the possible physiological significance of ATP as a mitogen in SMC was further studied. The effect of endothelin and heparin, which are released from endothelial cells, on ATP-dependent mitogenesis was investigated. Extracellular ATP acted synergistically with endothelin to stimulate a greater extent of [3H]thymidine incorporation than was seen with PDGF plus endothelin. Heparin, believed to have a regulatory role, partially inhibited the stimulation of DNA synthesis caused both by ATP and PDGF.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of adenosine 3':5'-monophosphate-dependent protein kinase and cAMP levels in ATP-dependent mitogenesis in Swiss 3T3 cells.

To investigate the role of cAMP-dependent protein kinase (PKA) and cAMP levels in ATP-dependent mitogenesis, Swiss 3T3 cells were transfected with an expression vector coding for (i) a mutated regulatory subunit of PKA (PKA mutant) or (ii) a yeast low Km cAMP phosphodiesterase gene (PDE mutant). The PKA mutant showed 70% reduced PKA activity. Phosphodiesterase activity increased 2.5-fold in the PDE mutant, leading to a great reduction of cAMP levels stimulated by ATP and other cAMP-increasing agents. The mitogenic responses of PKA and PDE mutants to insulin, epidermal growth factor, or 12-O-tetradecanoylphorbol-13-acetate were not significantly changed. However, the further stimulation by ATP, ADP, and adenosine 5'-(beta,gamma-imido)triphosphate in the presence of these growth factors was reduced by > 80%. Mitogenic effect of prostaglandin E2, forskolin, cholera toxin, or adenosine was inhibited in both mutants. The mitogenic stimulation by dibutyryl cAMP, which is resistant to phosphodiesterase, was inhibited in the PKA mutant, but not in the PDE mutant. A partial reduction of platelet-derived growth factor- or bombesin-stimulated mitogenesis, which involves protein kinase C as well as the cAMP signal, was observed in the mutants. These genetic results confirm pharmacological data on the role of PKA and cAMP levels in mitogenesis due to ATP and other growth factors.

Activation of early events of the mitogenic response by a P2Y purinoceptor with covalently bound 3'-O-(4-benzoyl)-benzoyladenosine 5'-triphosphate.

3'-O-(4-Benzoyl)benzoyl-ATP (BzATP), a photoaffinity analog of ATP, was used as a ligand for a P2Y purinoceptor (adenine nucleotide receptor) present in intact Swiss 3T3 and 3T6 cells and A-431 epidermoid carcinoma cells. Photolysis of serum-starved cells in the presence of 10-50 microM BzATP, followed by extensive washing to remove unincorporated BzATP, induced the release of arachidonic acid. A trace (less than 0.01%) of photoincorporated BzATP was as effective as when 50 microM BzATP or ATP was contained in the incubation medium during the assay. Photoincorporated BzATP also stimulated the production of prostaglandin E2 and the accumulation of cyclic AMP. In previous studies, we demonstrated that these three events are obligatory early steps in a pathway leading to DNA synthesis in the above cell lines. The evidence indicated that the purinoceptor activated by extracellular ATP or BzATP was linked to a pertussis toxin-sensitive GTP-binding protein. Consistent with these observations, we now find that pertussis toxin inhibits the effect of photoincorporated BzATP on arachidonic acid release. These results indicate that BzATP is an effective agonist for the P2Y purinoceptor concerned with stimulation of DNA synthesis in 3T3, 3T6, and A-431 cells. Furthermore, after photolysis it becomes irreversibly associated with intact cells and promotes the activation of early events required for DNA synthesis.

Extracellular ATP stimulates increases in Na+/K+ pump activity, intracellular pH and uridine uptake in cultures of mammalian cells.

Using 3T3 and 3T6 mouse fibroblasts and A431 epidermoid carcinoma cells, we previously observed that extracellular ATP and ADP were mitogens and they synergized with other growth factors (Huang, N., Wang, D. and Heppel, L. A. (1989) Proc. Natl. Acad. Sci. USA 86, 7904-7908). We now report that ATP and ADP stimulated Na+ entry, intracellular alkalinization and Na+/K+ pump activity, which are early events that had been proposed to play a central role in DNA synthesis. In addition, ATP, ADP and AMPPNP stimulated uridine uptake by a pathway involving arachidonic acid metabolism. In A431 cells, activation of protein kinase C also contributed to ATP-dependent stimulation of uridine uptake. Concentrations of indomethacin and pertussis toxin which inhibited uridine uptake also blocked arachidonic acid metabolism and DNA synthesis. ATP acted as a competence factor. Interestingly, ATP did not have to be continuously present to stimulate uridine uptake. It was equally effective even when it was washed away after brief treatment of cells.

Multiple signal transduction pathways lead to extracellular ATP-stimulated mitogenesis in mammalian cells: II. A pathway involving arachidonic acid release, prostaglandin synthesis, and cyclic AMP accumulation.

We have previously shown that extracellular ATP acts as a mitogen via protein kinase C (PKC)-dependent and independent pathways (Wang, D., Huang, N., Gonzalez, F.A., and Heppel, L.A. Multiple signal transduction pathways lead to extracellular ATP-stimulated mitogenesis in mammalian cells. I. Involvement of protein kinase C-dependent and independent pathways in the mitogenic response of mammalian cells to extracellular ATP. J. Cell. Physiol., 1991). The present aim was to determine if metabolism of arachidonic acid, resulting in prostaglandin E2 (PGE2) synthesis and elevation of cAMP levels, plays a role in mitogenesis mediated by extracellular ATP. Addition of ATP caused a marked enhancement of cyclic AMP accumulation in 3T3, 3T6, and A431 cells. Aminophylline, an antagonist of the adenosine A2 receptor, had no effect on the accumulation of cyclic AMP elicited by ATP, while it inhibited the action of adenosine. The accumulation of cyclic AMP was concentration dependent, which corresponds to the stimulation of DNA synthesis by ATP. The maximal accumulation was achieved after 45 min, with an initial delay period of about 15 min. That the activation of arachidonic acid metabolism contributed to cyclic AMP accumulation and mitogenesis stimulated by ATP in 3T3, 3T6, and A431 cells was supported by the following observations: (a) extracellular ATP stimulated the release of [3H]arachidonic acid and PGE2 into the medium; (b) inhibition of arachidonic acid release by inhibitors of phospholipase A2 blocked PGE2 production, cyclic AMP accumulation, and DNA synthesis activated by ATP, and this inhibition could be reversed by adding exogenous arachidonic acid; (c) cyclooxygenase inhibitors, such as indomethacin and aspirin, diminished the release of PGE2 and blocked cyclic AMP accumulation as well as [3H]thymidine incorporation in response to ATP; (d) PGE2 was able to restore [3H]thymidine incorporation when added together with ATP in the presence of cyclooxygenase inhibitors; (e) pertussis toxin inhibited ATP-stimulated DNA synthesis in a time- and dose-dependent fashion as well as arachidonic acid release and PGE2 formation. Other evidence for involvement of a pertussis toxin-sensitive G protein(s) in ATP-stimulated DNA synthesis as well as in arachidonic acid release is presented. In A431 cells, the enhancement of arachidonic acid and cyclic AMP accumulation by ATP was partially blocked by PKC down-regulation, implying that the activation of PKC may represent an additional pathway in ATP-stimulated metabolism of arachidonic acid. In all of these studies, ADP and AMP-PNP, but not adenosine, were as active as ATP.(ABSTRACT TRUNCATED AT 400 WORDS)