{"doi":"10.1002/jcp.1041380203","title":"Bicarbonate abolishes intracellular alkalinization in mitogen‐stimulated 3T3 cells","abstract":"<jats:title>Abstract</jats:title><jats:p>An increase in intracellular pH (pH<jats:sub>i</jats:sub>) following mitogenic stimulation has been reported in a variety of mammalian cells (<jats:italic>W. Moolenaar, Annu. Rev. Physiol.</jats:italic>, 48:363–376, 1986; E. Rozengurt, <jats:italic>Science</jats:italic>, 234:161–166, 1986). This increase is currently believed to constitute a “permissive” signal in the process of cell activation (A.E. Lagarde and J.M. Pouyssegur, <jats:italic>Cancer Biochem. Biophys.</jats:italic> 9: 1–14, 1986). Since the majority of studies of this phenomenon have been conducted in the nonphysiological milieu of bicarbonate‐free solutions, we have undertaken a study of the effects of bicarbonate and CO<jats:sub>2</jats:sub> on mitogen‐induced intracellular alkalinization in NIH 3T3 cells.</jats:p><jats:p>Using nuclear magnetic resonance (NMR) spectroscopy and novel <jats:sup>31</jats:sup>P NMR pH indicators (2‐amino‐phosphono‐carboxylic acids) we found that mitogen induces an increase in pH<jats:sub>i</jats:sub> of 0.16 units only in cells bathed in medium containing low concentrations of bicarbonate (less than 1 mM) and not in cells bathed in medium containing physiological levels of bicarbonate (10–30 mM). In addition to abolishing the mitogen‐induced alkalinization, bicarbonate stabilizes pH<jats:sub>i</jats:sub> at 7.25 units as the external pH (pH<jats:sub>e</jats:sub>) is varied from 7.0 to 7.6. In contrast, in a bicarbonate‐free medium pH<jats:sub>i</jats:sub> increases from 6.9 to 7.3 over the same range of external pHs.</jats:p><jats:p>At a constant external pH, increasing the bicarbonate/CO<jats:sub>2</jats:sub> concentration results in an increase in pH<jats:sub>i</jats:sub> from 6.9 in bicarbonate‐free solution to 7.25 in a bicarbonate‐buffered medium. This relationship is hyperbolic with half‐maximal effect occurring at a concentration of 0.4 mM bicarbonate at pH 7.05 and 37°C.</jats:p><jats:p>Our results suggest that the observations of mitogen‐induced alkalinization may be due to the use of nonphysiological bicarbonate‐free media. Since this increase in pH<jats:sub>i</jats:sub> is not observed in physiological media where bicarbonate concentrations are usually greater than 20 mM, we conclude that an increase in pH<jats:sub>i</jats:sub> is not an obligatory or usual part of the cellular response to growth factors in vivo.</jats:p>","journal":"Journal of Cellular Physiology","year":1989,"id":678692,"datarank":0.5333022092234121,"base_score":3.5553480614894135,"endowment":3.5553480614894135,"self_citation_contribution":0.5333022092234121,"citation_network_contribution":0.0,"self_endowment_contribution":0.5333022092234121,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":34,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":471239,"name":"Truman R. 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Since the majority of studies of this phenomenon have been conducted in the nonphysiological milieu of bicarbonate‐free solutions, we have undertaken a study of the effects of bicarbonate and CO<jats:sub>2</jats:sub> on mitogen‐induced intracellular alkalinization in NIH 3T3 cells.</jats:p><jats:p>Using nuclear magnetic resonance (NMR) spectroscopy and novel <jats:sup>31</jats:sup>P NMR pH indicators (2‐amino‐phosphono‐carboxylic acids) we found that mitogen induces an increase in pH<jats:sub>i</jats:sub> of 0.16 units only in cells bathed in medium containing low concentrations of bicarbonate (less than 1 mM) and not in cells bathed in medium containing physiological levels of bicarbonate (10–30 mM). In addition to abolishing the mitogen‐induced alkalinization, bicarbonate stabilizes pH<jats:sub>i</jats:sub> at 7.25 units as the external pH (pH<jats:sub>e</jats:sub>) is varied from 7.0 to 7.6. In contrast, in a bicarbonate‐free medium pH<jats:sub>i</jats:sub> increases from 6.9 to 7.3 over the same range of external pHs.</jats:p><jats:p>At a constant external pH, increasing the bicarbonate/CO<jats:sub>2</jats:sub> concentration results in an increase in pH<jats:sub>i</jats:sub> from 6.9 in bicarbonate‐free solution to 7.25 in a bicarbonate‐buffered medium. This relationship is hyperbolic with half‐maximal effect occurring at a concentration of 0.4 mM bicarbonate at pH 7.05 and 37°C.</jats:p><jats:p>Our results suggest that the observations of mitogen‐induced alkalinization may be due to the use of nonphysiological bicarbonate‐free media. Since this increase in pH<jats:sub>i</jats:sub> is not observed in physiological media where bicarbonate concentrations are usually greater than 20 mM, we conclude that an increase in pH<jats:sub>i</jats:sub> is not an obligatory or usual part of the cellular response to growth factors in vivo.</jats:p>","is_dataset_classified":null,"base_score":0.0,"endowment":0.0,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"2493002","pmcid":null,"openalex_id":null,"authors":[],"funders":[{"funder_name":"NCI NIH HHS","grant_id":"CA-06927","title":null},{"funder_name":"NCI NIH HHS","grant_id":"CA-41078","title":null}],"total_grants":2,"fwci":null,"citation_percentile":null,"influential_citations":0,"citation_trend":[],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjcp.1041380203","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcp.1041380203","host_type":"publisher"}],"fields_of_study":["Animals","Bicarbonates","Body Fluids","Carbon Dioxide","Cell Line","Fibroblasts","Hydrogen-Ion Concentration","Intracellular Fluid","Magnetic Resonance Spectroscopy","Mice","Mitogens"],"mesh_terms":["Cell Line","Intracellular Fluid","Fibroblasts","Body Fluids","Animals","Mice","Carbon Dioxide","Bicarbonates","Mitogens","Magnetic Resonance Spectroscopy","Hydrogen-Ion Concentration"],"keywords":[],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-17T05:50:25.845964Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}