UNLABELLED Bicarbonate secretion from cholangiocytes is required for appropriate adjustment of primary canalicular bile along the biliary tract. In human and rat cholangiocytes, bicarbonate secretion is mediated by anion exchanger (AE) 2, an electroneutral Na(+)-independent Cl(-)/HCO(3) (-) AE also involved in intracellular pH (pH(i)) regulation. In Ae2(a,b)-deficient mice, pH(i) is increased i...

Primary cultures of rat inner medullary collecting duct (IMCD) cells Na(+) dependently import HCO(3)(-) across the basolateral membrane through an undefined transport protein. We used RT-PCR, immunoblotting, and immunohistochemistry to identify candidate proteins for this basolateral Na(+)-HCO(3)(-) cotransport. The mRNA encoding the electroneutral Na(+)-HCO(3)(-) cotransporter NBCn1 was detect...

Accumulation of acid-stable and acid-labile C has been studied in cells isolated from cladophylls of Asparagus sprengeri regel, as a function of the concentrations of the various inorganic C (C(i)) species in the external medium.The rate of CO(2) fixation was higher when C(i) was supplied as CO(2) as opposed to HCO(3) (-), at the same concentration. Participation of HCO(3) (-) was indicated whe...

New high resolution observations of HCO J=1→0, HCN J=1→0, SO 22 → 11, and continuum with BIMA at 3.4 mm show that the NGC7538 IRS 9 cloud core is a site of active ongoing star formation. Our observations reveal at least three young bipolar molecular outflows, all ∼ 10,000 – 20,000 years old. IRS 9 drives a bipolar, extreme high velocity outflow observed nearly pole on. South of IRS 9 we find a ...

The study of infall motion helps us to understand the initial stages star formation. In this paper, we use IRAM 30-m telescope make mapping observations 24 sources confirmed in previous work. lines track gas motions are HCO+ (1-0) and H13CO+ (1-0). All show emissions, while 18 emissions. integrated intensity maps 17 clear clumpy structures; for line, 15 structures. We estimated column density u...

Proximal portion of duodenum is exposed to intermittent pulses of gastric H(+) discharged by the stomach. This review summarizes the mechanisms of duodenal mucosal integrity, mainly the role of mucus-alkaline secretion and the mucous barrier protecting surface epithelium against gastric H(+). The mucous barrier protects the leaky duodenal epithelium against each pulse of gastric H(+), which pen...

Fluid secretion is essential for intestinal function and, in eutherian mammals, is driven by electrogenic Cl(-) transport, which is dependent upon a bumetanide-sensitive, basolateral Na(+)/K(+)/2 Cl(-) cotransporter, NKCC1. However, ileal secretion in the brushtail possum, a marsupial, involves a fundamentally different process, since NKCC1 expression is low in this tissue and the secretagogue-...

Diatoms are an important functional group of marine phytoplankton because of their role in the fixation of atmospheric carbon dioxide (CO2) and transfer of organic carbon to deep waters. Carbon-concentrating-mechanisms, such as active CO2 and bicarbonate (HCO ) uptake and carbonic 3 anhydrase activity, are believed to be essential to marine photosynthesis, because the main carbon-fixing enzyme,...

Diffusion of (14)C-labeled CO(2) was measured through lipid bilayer membranes composed of egg lecithin and cholesterol (1:1 mol ratio) dissolved in n-decane. The results indicate that CO(2), but not HCO(3-), crosses the membrane and that different steps in the transport process are rate limiting under different conditions. In one series of experiments we studied one-way fluxes between identical...

1. Folate metabolism was studied during the early phases of liver regeneration after partial hepatectomy in rats accustomed to eating during the first 8h of a daily 12h dark period. 2. The content of 5-CH(3)-H(4)folate was drastically decreased during the first hours of regeneration. 3. The total HCO-H(4)folate coenzymes showed a constant decrease during the first 3 days of regeneration, and a ...