PubMed · 7802808
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A Fudge, B Rumbelow, M Peake. 1994. Specificity problems with Hitachi chloride electrodes.. https://pubmed.ncbi.nlm.nih.gov/7802808/
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Cyanobacteria possess an inducible mechanism which enables them to concentrate inorganic carbon (Ci) within the cells. An inactivation library was used to raise the high-CO2-requiring mutant of Synechococcus PCC 7942, IL-2, impaired in HCO3- transport. Analysis of the relevant genomic DNA detected several modifications, probably due to the single crossover recombination, leading to inactivation of ORF467 (designated ictB) in IL-2. IctB contains 10 trans-membrane regions and is homologous to several transport-related proteins from various organisms. Kinetic analyses of HCO3- uptake in the wild type and IL-2 suggested the presence of two or three HCO3- carriers exhibiting different affinities to HCO3-.
Functional properties of a cloned human kidney Na+:HCO3- cotransporter (NBC-1) were studied in cultured HEK-293 cells that were transiently transfected with NBC-1 cDNA. The Na+:HCO3- cotransporter activity was assayed as the Na+ and HCO3-dependent pHi recovery from intracellular acidosis with the use of the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. In acid-loaded cells and in the presence of amiloride (to block Na+/H+ exchange), switching to a Na+-containing solution (115 mM) resulted in rapid pHi recovery only in the presence of HCO3-. This recovery was completely abolished by 300 microM 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid. Replacing the Na+ with Li+ (115 mM) caused significant HCO3--dependent, DIDS-sensitive pHi recovery from intracellular acidosis, with Li+ showing lower affinity than Na+. Potassium (K+) had no affinity for the Na+:HCO3- cotransporter. The Na+-dependent HCO3- cotransport was abolished in the presence of 0.2 mM harmaline. The Na+:HCO3- cotransporter could also function in Na+:OH- cotransport mode, although only at high external pH (7.8). Based on functional similarities with the mammalian kidney experiments, we propose that NBC-1 is the proximal tubule Na+:HCO3- cotransporter.
OBJECTIVES: To evaluate the effects of menopausal hot flashes on arterial blood gas measurements. METHODS: Twelve postmenopausal women with frequent hot flashes were enrolled in this study. Blood samples from femoral artery were collected before and during menopausal hot flashes in each subject, and all blood samples were analyzed for pH, pCO2, pO2, HCO3 standard, total CO2, and base excess. Arterial blood gas parameters before and during menopausal hot flashes were compared statistically. RESULTS: pH measurements decreased significantly during hot flashes (P < 0.05); although the difference was found to be statistically significant, the amount of decrease and the range in which the change took place led us to conclude that this change was clinically insignificant. Other parameters did not show any statistically significant differences between the preflash and flash measurements. CONCLUSIONS: Our results indicate that menopausal hot flashes do not have any clinically significant effects on arterial blood gas measurements.