The cortical collecting duct (CCD) B cell possesses an apical anion exchanger dissimilar to AE1, AE2, and AE3. The purpose of these studies was to characterize this transporter more fully by examining its regulation by CO2 and HCO3. We measured intracellular pH (pHi) in single intercalated cells of in vitro microperfused CCD using the fluorescent, pH-sensitive dye, 2',7'-bis(2-carboxyethyl)-5(6...

Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechan...

This study investigated the effect of high CO2 (4%) from embryonic day (ED)10 until ED16 on the acid-base balance and related parameters in the chicken embryo. From ED10 to ED16, blood was taken from a vein from the chorioallantois membrane and was analyzed for pH, partial pressure of CO2, partial pressure of O2 (pO2), [HCO3(-)], [K+], and [Ca2+]. Allantoic fluid was taken for measurement of pH...

Working with isolated perfused S2 proximal tubules, we asked whether the basolateral CO2 sensor acts, in part, by raising intracellular Ca2+ concentration ([Ca2+]i), monitored with the dye fura 2 (or fura-PE3). In paired experiments, adding 5% CO2/22 mM HCO3- (constant pH 7.40) to the bath (basolateral) solution caused [Ca2+]i to increase from 57 +/- 3 to 97 +/- 9 nM(n = 8, P < 0.002), whereas ...

Intestinal HCO3- secretion is essential to marine teleost fish osmoregulation and comprises a considerable source of base efflux attributable to both serosal HCO3- and endogenous CO2 hydration. The role of intestinal HCO3- secretion in dynamic acid-base balance regulation appears negligible in studies of unfed fish, but evidence of high intestinal fluid [HCO3-] in fed marine teleosts led us to ...

Microalgae are a large and diverse group of photosynthetic organisms which can use of solar energy to fixed inorganic carbon (Ci) with efficiency (2-10%) that are ten times greater than higher plants (<1%) due to their high growth rate (1to 3-fold increases in biomass per day) [1,2]. Although CO2 is the predominant carbon source for microalgal cultivation, the low level of dissolution of CO2 in...

The renal proximal tubule (PT) plays a major role in whole-body pH homeostasis by secreting H(+) into the tubule lumen. Previous work demonstrated that PTs respond to basolateral changes in [CO2] and [HCO3-] by appropriately altering H(+) secretion-responses blocked by the ErbB inhibitor PD168393, or by eliminating signaling through AT1 angiotensin receptors. In the present study, we analyze ph...

We found that a carbonic anhydrase, YadF, is essential for cell growth in the absence of another carbonic anhydrase, CynT, in Escherichia coli. However, mutant strains lacking both of them grew at high CO2 concentrations (5%), where non-enzymatic mechanisms generate HCO3-. This suggests that these carbonic anhydrases are essential because they maintain HCO3- levels at ambient CO2 concentrations.

CO2 excretion in trout is dependent upon the Haldane effect and the release of protons (Bohr protons) from haemoglobin during oxygenation of the blood. Oxygenation of whole blood from trout in vitro, resulted in a non-linear release of Bohr protons over the haemoglobin-oxygen (Hb-O2) equilibrium curve, where the majority of Bohr protons were released between 60 and 100% of Hb oxygen saturation ...

The ascomycete Candida albicans is the most common fungal pathogen in immunocompromised patients . Its ability to change morphology, from yeast to filamentous forms, in response to host environmental cues is important for virulence . Filamentation is mediated by second messengers such as cyclic adenosine 3',5'-monophosphate (cAMP) synthesized by adenylyl cyclase . The distantly related basidiom...