No abstract available.
Animal ; Bicarbonates/metabolism* ; Biological Transport/physiology ; Pancreatic Ducts/metabolism* ; Perfusion

Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) is an important ubiquitous cytosol enzyme that fixes HCO3 together with phosphoenolpyruvate (PEP) and yields oxaloacetate that can be converted to intermediates of the citric acid cycle. In plant cells, PEPC participates in CO2 assimilation and other important metabolic pathways, and it has broad functions in different plant tissues. PEPC is also involved in the regulation of storage product synthesis and metabolism in seeds, such as affecting the metabolic fluxes from sugars/starch towards the synthesis of fatty acids or amino acids and proteins. In this review, we introduced the progress in classification, structure and regulation of PEPC in plant tissues. We discussed the potential applications of plant PEPCs in genetic engineering. The researches in functions and regulation mechanism of plant PEPCs will provide beneficial approaches to applications of plant PEPCs in high-yield crops breeding, energy crop and microbe genetic engineering.
Bicarbonates ; chemistry ; Genetic Engineering ; Oxaloacetic Acid ; chemistry ; Phosphoenolpyruvate ; chemistry ; Phosphoenolpyruvate Carboxylase ; chemistry ; genetics ; metabolism ; Plants ; enzymology

The physiological changes that occur to sperm during the residence in the female tract are collectively referred to as "capacitation". The mechanism of action by which these compounds promote capacitation is poorly understood at the molecular level. However, some molecular events significant to the initiation of capacitation have been identified, such as the correlation of capacitation with cholesterol efflux from the sperm plasma membrane, increased membrane fluidity, modulations in intracellular ion concentrations, hyperpolarization of the sperm plasma membrane and increased protein tyrosine phosphorylation. This review discusses recent progress in elucidation mechanisms which regulate sperm capacitation.
Bicarbonates ; metabolism ; Calcium ; metabolism ; Cholesterol ; metabolism ; Cyclic AMP ; physiology ; Humans ; Ion Transport ; Male ; Membrane Potentials ; Phosphorylation ; Sperm Capacitation

The luminal fluid environment of the female reproductive tract is considered critical for the sperm to undergo a series of molecular events leading to the final acquisition of their fertilizing capacity. It has been shown that the fluid in the female reproductive tract contains high content of HCO3- and it plays an important role in sperm functions including sperm motility, capacitation, hyperactivation and acrosome reaction. This review summarizes the effects of HCO3- on sperm functions occurring in the female reproductive tract and discusses the transport mechanisms involved in mediating uterine HCO3- secretion. New evidence is also presented to show possible cause of female infertility due to defective HCO3- transporting mechanism.
Animals ; Bicarbonates ; metabolism ; Female ; Fertilization ; physiology ; Humans ; Male ; Sperm Capacitation ; physiology ; Sperm-Ovum Interactions ; physiology ; Uterus ; metabolism ; secretion

Sperm must be capacitated before sperm-ovum fusion. Capacitation was once considered as hyperactivation. But now many investigators thought that capacitation wasn't equal to hyperactivation, and that sperm hyperactivation might be a moiety of capacitation or the result of capacitation. In the present, the methods used to study sperm capacitation include fertilization in vitro, induction of sperm acrosome reaction, FITC-labeled chlortetracycline and plant hemoagglutinin. The studies on sperm capacitation in vitro mainly focused on the inductive substances of sperm capacitation and subsequent results analysis. It could lay foundation for the manifestation of molecular mechanism of sperm capacitation and destination of sperm capacitation in molecular levels.
Adenylyl Cyclases ; physiology ; Bicarbonates ; metabolism ; Calcium ; metabolism ; Humans ; Male ; Phosphorylation ; Sperm Capacitation ; drug effects ; physiology ; Sperm Motility

OBJECTIVETo study the difference of plasma actual bicarbonate between the children with growth hormone deficiency (GHD) and idopathatic short stature (ISS) and to value the plasma bicarbonate standard deviation scores (SDS) in diagnosis of GHD.

METHODSForty-seven short stature children were divided into two groups (GHD and ISS) according to the peak GH response to provocative test. Plasma actual bicarbonate concentrations anion gap (AG), base excess and electrolytes were measured in 47 children with short stature before GH provocative tests.

RESULTSThe mean plasma actual bicarbonate concentrations, bicarbonate SDS were (22.60+/-1.29)mmol/L and -0.27+/-0.98 respectively in GHD children, which were significantly lower than those of ISS children (P<0.01), whereas AG was higher than that of ISS children [(11.73+/-4.52 vs 7.87+/-1.70) mmol/L], P<0.01. Seventy-two percent of patients with bicarbonate SDS

CONCLUSIONPlasma actual bicarbonate concentrations and bicarbonate SDS are lower in patients with GHD than those in patients with idopathatic short stature. Evaluation of plasma bicarbonate SDS of short stature children can predict the probability of GHD, especially when bicarbonate SDS is less than 1 s.

Acid-Base Equilibrium ; Adolescent ; Bicarbonates ; blood ; Child ; Child, Preschool ; Female ; Growth Disorders ; metabolism ; Human Growth Hormone ; deficiency ; Humans ; Male

HCO3(-) reabsorption in the renal tubules plays a critically important role in maintaining the global acid-base balance. Loss of HCO3(-) causes metabolic acidosis. Proximal renal tubule is the major site for HCO3(-) reabsorption, accounting for more than 80% of total HCO3(-) reabsorption along the nephron. Over the past more than half centuries, tremendous progresses have been made on understanding the molecular mechanisms underlying the HCO3(-) reabsorption in proximal tubules. The transepithelial movement of HCO3(-) involves the coordinated operation of machineries on both the apical and the basolateral membranes of the epithelial cells. On the apical domain, Na(+)-H(+) exchanger NHE3 and the vacuolar H(+)-ATPase are two major pathways mediating the apical uptake of HCO3(-)-related species. Taken together, NHE3 and H(+)-ATPase are responsible for about 80% of HCO3(-) reabsorption in the proximal tubule. The remaining 20% is likely mediated by pathways yet to be characterized. On the basolateral membrane, NBCe1 represents the only major known pathway mediating the extrusion of HCO3(-) coupled with Na(+) into the interstitial space. In the present article, we provide a historical view about the studies on the mechanisms of HCO3(-) reabsorption since 1940s. Moreover, we summarize the latest progresses emerging over the past decade in the physiological as well as pathological roles of acid-base transporters underlying the HCO3(-) reabsorption in proximal tubules.
Acidosis ; physiopathology ; Animals ; Bicarbonates ; metabolism ; Humans ; Kidney Tubules, Proximal ; physiopathology ; Sodium-Hydrogen Exchangers ; physiology ; Vacuolar Proton-Translocating ATPases ; physiology

Luminal acidification in the epididymis is an important process for the regulation of male fertility. Low pH and low bicarbonate concentration are among key factors that keep spermatozoa in a dormant state while they mature and are stored in this organ. Although significant bicarbonate reabsorption is achieved by principal cells in the proximal regions of the epididymis, clear and narrow cells are specialized for net proton secretion. Clear cells express very high levels of the vacuolar proton pumping ATPase (V-ATPase) in their apical membrane and are responsible for the bulk of proton secretion. In the present paper, selected aspects of V-ATPase regulation in clear cells are described and potential pathologies associated with mutations of some of the V-ATPase subunits are discussed.
Adenosine Triphosphatases ; metabolism ; Adenylyl Cyclases ; metabolism ; Animals ; Bicarbonates ; metabolism ; Epididymis ; metabolism ; Humans ; Hydrogen-Ion Concentration ; Male ; Mice ; Proton Pumps ; metabolism ; Vacuoles ; enzymology

Cystic fibrosis (CF) of the pancreas is the most widely accepted name of the most common fatal inherited single gene defect disease among Caucasians. Its incidence among other races is thought to be significantly less, but mutations in the gene have been reported in most, if not all, major populations. This review is intended to give general concepts of the molecular as well as physiological basis of the pathology that develops in the disease. First, an overview of the organ pathology and genetics is presented, followed by the molecular structure of the gene product (cystic fibrosis transmembrane conductance regulator, CFTR), its properties, functions, and controls as currently understood. Second, since mutations appear to be expressed primarily as a defect in electrolyte transport, effects and mechanisms of pathology are presented for two characteristically affected organs where the etiology is best described: the sweat gland, which excretes far too much NaCl ("salt") and the pancreas, which excretes far too little HCO3(- )("soda"). Unfortunately, morbidity and mortality in CF develop principally from refractory airway infections, the basis of which remains controversial. Consequently, we conclude by considering possible mechanisms by which defects in anion transport might predispose the CF lung to chronic infections.
Anions ; metabolism ; Bicarbonates ; Cystic Fibrosis ; physiopathology ; Cystic Fibrosis Transmembrane Conductance Regulator ; metabolism ; Humans ; Ion Transport ; Pancreas ; physiopathology ; Sodium Chloride ; Sweat Glands ; physiopathology

We performed a bentiromide test in 25 patients with chronic pancreatitis and 7 normal controls to evaluate pancreatic exocrine function, and compared the test results of patients with their endoscopic retrograde pancreatography(ERP) findings. The cumulative 6-hour recovery rate of para-aminobenzoic acid(PABA) in the urine was significantly lower in patients with chronic pancreatitis(55.8 +/- 24.2%) than in controls(82.0 +/- 10.0%). Among 25 patients with chronic pancreatitis, however, 7 patients showed normal recovery rates of PABA. Pancreatograms of the patients represented 4 mild changes, 5 moderate changes, and 16 marked changes. The average 6-hour recovery rates of PABA of the groups were 56.9 +/- 21.6%, 78.4 +/- 10.5%, and 47.2 +/- 23.7%, respectively. Urinary PABA recovery rates were found subnormal as follows: 3(75%) in the mild changes group; 1(20%) in the moderate changes group; and 14(87.5%) in the marked changes group. We found hardly any correlation between the degree of functional impairment and the changes noted by ERP. These findings suggest that both the pancreatic function test and morphologic study are required to evaluate the degree of functional impairment in patients with chronic pancreatitis.
4-Aminobenzoic Acid/diagnostic use ; 4-Aminobenzoic Acid/analogs & derivatives* ; Adult ; Aged ; Bicarbonates/metabolism ; Chronic Disease ; Comparative Study ; Female ; Human ; Male ; Middle Age ; Pancreas/radiography* ; Pancreatitis/diagnosis*