During hypoxia, fishes exhibit a characteristic hypoxic bradycardia, the functional significance of which remains debated. Here, we investigated the hypothesis that hypoxic bradycardia primarily safeguards cardiac performance. In preparations from the European eel (Anguilla anguilla), a decrease in stimulation frequency from 40 to 15 beats min(-1), which replicates hypoxic bradycardia in vivo, ...

The cellular distribution of the NH2-terminal electrogenic Na+-HCO3(-) cotransporter (NBCe1) variants NBCe1-A and NBCe1-B has been investigated in rat kidney and submandibular gland (SMG) under physiological conditions and after systemic acid-base perturbations. Moreover, the in vivo data were complemented in vitro by using an immortalized cell line derived from the S1 segment of the proximal t...

This work aims to investigate the hydrochemical characteristics and formation mechanisms of shallow groundwater in a part Nanchang section Ganfu plain. The data from 90 samples were interpreted by methods mathematical statistics, Piper diagrams, Gibbs plots, ratio graphs ions, geochemical modeling. results show that is weakly acidic, average concentration cation decrease Ca2+ > Na+ Mg2+ K+, ...

This study aimed to assess the effects of different dialysate bicarbonate concentrations in correcting acid-base imbalance in 53 stable hemodialysis patients in a university-hemodialysis unit. Three different bicarbonate concentrations were assigned, i.e. 25 mEq/L in 10, 30 mEq/L in 30, and 35 mEq/L in 13 patients. Blood gas analyses from arterial line blood samples before and after dialysis in...

OBJECTIVE To review the normal human acid-base physiology and the pathophysiology and management of acid-base disturbances in a two-part presentation. DATA SOURCES Articles and published peer-review abstracts and a review of studies reported from 1990 to 2000 and identified through a MEDLINE search of the English language literature on acid-base balance. SUMMARY OF REVIEW Acid-base disorder...

To examine whether Cl-coupled HCO3 transport mechanisms were present on the basolateral membrane of the mammalian proximal tubule, cell pH was measured in the microperfused rat proximal convoluted tubule using the pH-sensitive, intracellularly trapped fluorescent dye (2',7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein. Increasing the peritubular Cl concentration from 0 to 128.6 meq/liter caused ...

Gastric HCO3(-) transport (basal) studied in isolated amphibian mucosa and mammalian stomach in vivo amounts to 2-10% of maximal H+ secretion. Duodenal mucosa, devoid of Brunner's glands, transports HCO3(-) at a greater rate (per unit surface area) than either stomach or jejunum in vitro and in vivo. Gastric (but not duodenal) HCO3(-) transport is stimulated by dibutyryl cGMP, carbachol, and ch...

The epithelial anion channel CFTR interacts with multiple PDZ domain-containing proteins. Heterologous expression studies have demonstrated that the Na+/H+ exchanger regulatory factors, NHERF1, NHERF2, and PDZK1 (NHERF3), modulate CFTR membrane retention, conductivity, and interactions with other transporters. To study their biological roles in vivo, we investigated CFTR-dependent duodenal HCO3...

Because endothelin receptor inhibition blunts increased distal tubule acidification induced by dietary acid, we examined whether endothelin-1 (ET-1) increases acidification of in vivo perfused distal tubules of anesthetized rats. ET-1 was infused intra-aortically (1.4 pmol ⋅ kg-1 ⋅ min-1) into control animals and into those with increased distal tubule HCO3 secretion induced by drinking 80 mM N...

Isometrically mounted and electrically paced myocardial ventricular strips of carp have a much higher capacity to develop force during severe hypoxia and to redevelop force after it than those of rainbow trout. When the concentrations of CO2 and HCO3-in the solutions surrounding the strips were increased together, such that pH remained constant, the force developed during hypoxia increased. The...