The outer medullary collecting duct (OMCD) plays an important role in mediating transepithelial HCO transport [J(HCO(3)(-))] and urinary acidification. HCO absorption by type A intercalated cells in the OMCD inner stripe (OMCD(is)) segment is thought to by mediated by an apical vacuolar H(+)-ATPase and H(+)-K(+)-ATPase coupled to a basolateral Cl(-)-HCO exchanger (AE1). Besides these Na(+)-inde...

Previous experimental and theoretical studies of the radical dissociation channel of T(1) acetaldehyde show conflicting behavior in the HCO and CH(3) product distributions. To resolve these conflicts, a full-dimensional potential-energy surface for the dissociation of CH(3)CHO into HCO and CH(3) fragments over the barrier on the T(1) surface is developed based on RO-CCSD(T)/cc-pVTZ(DZ) ab initi...

We have imaged the central ∼ 1 kpc of the circumnuclear starburst disk in the galaxy NGC253 in the HCN(1→0), HCO(1→0), and CO(1→0) transitions at 60 pc resolution using the Owens Valley Radio ObservatoryMillimeter-Wavelength Array (OVRO). We have also obtained Atacama Pathfinder Experiment (APEX) observations of the HCN(4→3) and the HCO(4→3) lines of the starburst disk. We find that the emissio...

Oceanic CO(2) has increased from 280 to 380 μatm since preindustrial times and is expected to reach 1,900 μatm by 2300. In addition, regional upwelling zones exhibit levels up to 2,300 μatm, making exploration at future global projected CO(2) levels ecologically relevant today. Recent work has demonstrated that CO(2) exposure as low as 1,000 μatm induces acidosis in toadfish (Opansus beta), lea...

Eosinophils are one of the major mammalian effector cells encountered by helminths during infection. In the present study, we investigated the effects of eosinophil granule exposure on the sheep parasitic nematode Haemonchus contortus as a model. H. contortus eggs exposed to eosinophil granule products showed increased rhodamine 123 efflux and this effect was not due to loss of egg integrity. R...

Whole animal studies using seawater European flounder (Platichthys flesus) revealed that increasing intestinal [Ca(2+)] to 20 mM stimulated net HCO(3)(-) base secretion by 57%, but this was effectively balanced by an increase in net acid secretion, likely from the gills, to maintain whole animal acid-base status. Higher Ca(2+) concentrations (40 and 70 mM) in ambient seawater resulted in reduce...

There is abundant evidence implicating a role for intracellular pH (pHin) in the proliferative response of many cells to mitogenic agents. In mammalian cells, pHin is generally regulated by two systems: Na+/H+ exchange and HCO; transport. Activation of Na+/H+ exchange is one of the earliest responses of mammalian cells to mitogens. In the absence of HCO;, this activation raises the pHin. Howeve...

Mammalian sperm are incapable of fertilizing eggs immediately after ejaculation; they acquire fertilization capacity after residing in the female tract for a finite period of time. The physiological changes sperm undergo in the female reproductive tract that render sperm able to fertilize constitute the phenomenon of "sperm capacitation." We have demonstrated that capacitation is associated wit...

Hydrogen sulfide (H(2)S), an endogenous gaseous mediator, produces both vasorelaxation and vasoconstriction at different concentrations. We found in the present study that NaHS, an H(2)S donor, produced stronger vasorelaxant and weaker vasoconstrictive effects in HEPES solution compared with those achieved in Krebs solution. We further screened the buffer components and found that bicarbonate (...

We tested a number of inhibitory monovalent anions for their primary site of action on photosystem II(PSII) in chloroplasts. We find that the inhibitory effects of F(-), HCO(2) (-), NO(2) (-), NO(3) (-), and CH(3)CO(2) (-) are all reversed by addition of a high concentration of HCO(3) (-). This class of anions competitively inhibits H(14)CO(3) (-) binding to PSII. All of those anions tested red...