Mg2+-HCO 3 − -ATPase and carbonic anhydrase in rat intestinal mucosa

Cellular and Molecular Life Sciences - Mg2+-dependent and HCO 3 − -stimulated ATPase activity was highest in the brush border (microvilli) of rat duodenal mucosa compared with that of the...     

Absorption of iron from gut into blood: Sex- and time-related studies in rats

Summary As judged from 2-h blood level curves, adult female rats absorbed more Fe^II per cm² of gross duodenal mucosa than adult male rats. By contrast, the 2-h blood level curves per cm² of mucosa of proximal jejunum did not differ significantly in male and female rats although in both sexes, iron was absorbed more efficiently from the duodenum. This research was supported by grant RO1 AM 12381 from the National Institute of arthritis, Diabetes and Digestive and Kidney Diseases, National Institutes of Health.     

Inhibition of erythrocyte ATPase activity by aclacinomycin and reverse effects of ascorbate on ATPase activity

We studied the effect of aclacinomycin on human erythrocyte membrane enzymes. Aclacinomycin inhibited ATPase, including Na-K-dependent ATPase, ouabain insensitive ATPase and Ca-ATPase. However acetylcholinesterase was not inhibited by aclacinomycin. The ATPase activities were not inhibited by aclacinomycin if ascorbate was added to the incubation mixture. However other reducing agents, alpha-tocopherol, superoxide dismutase and catalase had no effect on ATPase activity. Ascorbate may protect membrane proteins and lipids from peroxidate damage.     

Epithelial-mesenchymal interaction in differentiation of duodenal epithelium of fetal rats in organ culture

Summary Epithelial-mesenchymal interaction in the differentiation of duodenal epithelium of fetal rats was investigated by recombination experiments in vitro. The proportion of goblet cells in duodenal epithelium was significantly greater on recombination of developing duodenal epithelium with mesenchyme of the glandular stomach than on recombination with that of the duodenum. Mesenchyme of the glandular stomach or forestomach was better than duodenal mesenchyme in supporting morphogenesis of duodenal epithelium. Treatment of tissues with N-methyl-N-nitro-N-nitrosoguanidine (MNNG) did not affect these tissue interactions.This work was supported by grants-in-aid for cancer research from the Ministry of Education, Science and Culture, Japan.Acknowledgment. The authors wish to express their gratitude to Prof. T. Mizuno of the University of Tokyo for valuable suggestions.     

The Ca2+-transport ATPases in smooth muscle

Summary A calmodulin stimulated Ca²⁺-transport ATPase which has many of the characteristics of the erythrocyte type Ca²⁺-transport ATPase has been purified from smooth muscle. In particular, the effect of calmodulin on these transport enzymes is mimiced by partial proteolysis and antibodies against erythrocyte Ca²⁺-transport ATPase also bind to the smooth muscle (Ca²⁺+Mg²⁺)ATPase. A correlation between the distribution of the calmodulin stimulated (Ca²⁺+Mg²⁺)ATPase and (Na⁺+K⁺)ATPase activities in smooth muscle membranes separated by density gradient centrifugation suggests a plasmalemmal distribution of this (Ca²⁺+Mg²⁺)ATPase. A phosphoprotein intermediate in smooth muscle which strongly resembles the corresponding phosphoprotein in sarcoplasmic reticulum of skeletal muscle may indicate the presence in smooth muscle of a similar type of Ca²⁺-transport ATPase.     

Caveolated cells observed in the duodenal glands of the white-tailed deer

Summary This study reports the presence of caveolated cells in the duodenal glands of the white-tailed deer. Caveolated cells have not been observed previously in the duodenal glands of other species studied to date.     

Direct electric measurement of the functioning of adenosine triphosphatase of submitochondrial particles of beef heart]

A direct potential measurement of the activity of bound ATPase has been achieved with beef heart submitochondrial particles adhering to a thick phospholipidic membrane. Electric signals (90 mV amplitude) were found to be fully sensitive to ATPase inhibitors and uncouplers.     

Inhibition of E coli ATPase activity by a troponin component, TN-I, and by mitochondrial ATPase inhibitor.

The enzymic activity of Mg2+- or Ca2+-stimulated ATPase from Escherichia coli was inhibited by one of the troponin components, TN-I, and by mitochondrial ATPase inhibitor (F1-inhibitor). The inhibitory ability of component TN-I against Mg2+-stimulated AtPase activity was lost after digestion of component TN-I with trypsin. The Mg2+-stimulated ATPase activity inhibited by component TN-I was completely restored by the addition of another troponin component TN-C.     

Inhibition ofE. coli ATPase activity by a troponin component,TN-I,and by mitochondrial ATPase inhibitor

Summary The enzymic activity of Mg²⁺-or Ca²⁺-stimulated ATPase fromEscherichia coli was inhibited by one of the troponin components, TN-I, and by mitochondrial ATPase inhibitor (F₁-inhibitor). The inhibitory ability of component TN-I against Mg²⁺-stimulated ATPase activity was lost after digestion of component TN-I with trypsin. The Mg²⁺-stimulated ATPase activity inhibited by component TN-I was completely restored by the addition of another troponin component, TN-C.     

Histochemical characterization of the red fibres in pigeon pectoralis muscle.

Red fibres of the pigeon pectoralis muscle showed high ATPase reaction at pH 9.4. Veronal-acetate pretreatment completely inhibited the ATPase reaction in these red fibres but not in type I fibres of the gastrocnemius. The former are type II red muscle fibres and hence are unlike type I red, the so-called slow-twitch muscle fibres.     

Na, K-ATPase in the salivary gland of the ixodid tick Amblyomma hebraeum (Koch) and its relation to the process of fluid secretion.

Total and ouabain-sensitive ATPase activities were determined in the salivary glands of ticks throughout the feeding cycle. Activities were very low in unfed specimens. In the glands of feeding females, the activities rose until a maximum was reached for both ATPase components at approximately 200 mg. The activities remain low in males throughout the feeding period. These findings are discussed in relation to the fluid secretory process of the salivary glands.     

Histochemical characterization of the red fibres in pigeon pectoralis muscle

Summary Red fibres of the pigeon pectoralis muscle showed high ATPase reaction at pH 9.4. Veronal-acetate pretreatment completely inhibited the ATPase reaction in these red fibres but not in type I fibres of the gastrocnemius. The former are type II red muscle fibres and hence are unlike type I red, the so-called slow-twitch muscle fibres.     

(Ca−Mg) ATPase activity of human erythrocyte membranes: Influence of incubation buffer

Summary Activity of the (Ca–Mg) ATPase of human red blood cell membranes is highly dependent on the specific buffer used in the ATPase assay. Activity is highest in histidine and/or imidazole buffers and is lowest in HEPES buffer.This research was supported by Public Health Service Grants AH-16436 and GM 00109-16. We wish to acknowledge the useful suggestions of Thomas R. Hinds and the excellent clerical assistance of Ms Laurie Asher.     

Enzyme histochemical reaction of mouse ova

Zusammenfassung Nachweis, dass in den Eiern im Mäuseeileiter grosse Quantitäten von ATPase, Cytochromaoxidase, Glukose-6-phosphat-dehydrogenase, Mitochondrialdehydrogenasen, saure und alkalische Phosphatasen lokalisiert sind. In den Eiern im Eierstock hingegen wurden ebenfalls ATPase, Phosphatase und Lactat-dehydrogenase festgestellt, obwohl von den Mitochondrialenzymen nur geringe Mengen gefunden wurden.     

Comparative effects of ouabain, natriuretic factor and ammonium chloride in the toad urinary bladder

Electrical changes and direct effects on Na-K ATPase activity induced by an endogenous digitalis-like natriuretic factor (NF), NH4Cl and ouabain were studied in toad bladders. NF inhibited the SCC and the Na-K ATPase activity in a similar manner to ouabain, but induced a greater increase in calculated direct current resistance (R) (p less than 0.05). NH4Cl was a weak inhibitor of Na-K ATPase activity, although it produced steeper SCC inhibition slopes than those observed with ouabain or NF (p less than 0.01). The data suggested the same mechanism of action of NF and ouabain on the sodium pump, with an additional effect of the former on apical sodium permeability of the cells and/or closure of paracellular routes leading to an increased tissue resistance. In contrast, the effects of NH4Cl were mostly compatible with intracellular inhibition of apical sodium entry into the cell.     

Na,K-ATPase in the salivary gland of the ixodid tickAmblyomma hebraeum (Koch) and its relation to the process of fluid secretion

Summary Total and ouabain-sensitive ATPase activities were determined in the salivary glands of ticks throughout the feeding cycle. Activities were very low in unfed specimens. In the glands of feeding females, the activities rose until a maximum was reached for both ATPase components at approximately 200 mg. The activities remain low in males throughout the feeding period. These findings are discussed in relation to the fluid secretory process of the salivary glands.Generously supported by the Swiss National Fund for Scientific Research, request No. 3.3460.74 We are also very grateful to Mr.H. Bouvard, Ciba-Geigy Ltd., Les Barges, Vouvrey, VS, for supplying us with ticks.     

Effects of various inhibitors and 2,4-dinitrophenol on adenosine triphosphatase from Malpighian tubules ofLocusta migratoria L

Summary Both Mg²⁺-ATPase and HCO ₃ ^– -stimulated ATPase activity were inhibited by sodium azide and to a lesser extent ethacrynic acid and amiloride. 1 mM DNP stimulated Mg²⁺-ATPase activity by 22% and HCO ₃ ^– -stimulated ATPase activity by 7%.     

Zur Wirkung des Calciums auf die Myofibrillen-ATPase des Herzmuskels

Summary The inhibition of cardiac myofibrillar ATPase activity by EDTA can be completely reversed by Ca⁺⁺ under certain experimental conditions. This shows that there is no fundamental difference between the reaction of cardiac myofibrillar ATPase and the tension development of glycerinated cardiac fibres, as was supposed byBriggs andHannah on account of the results ofParker andBerger.     

The plasma membrane proton-translocating ATPase

Living cells require membranes and membrane transporters for the maintenance of life. After decades of biochemical scrutiny, the structures and molecular mechanisms by which membrane transporters catalyze transmembrane solute movements are beginning to be understood. The plasma membrane proton-translocating adenosine triphosphatase (ATPase) is an archetype of the P-type ATPase family of membrane transporters, which are important in a wide variety of cellular processes. The H+-ATPase has been crystallized and its structure determined to a resolution of 8 angstrom in the membrane plane. When considered together with the large body of biochemical information that has been accumulated for this transporter, and for enzymes in general, this new structural information is providing tantalizing insights regarding the molecular mechanism of active ion transport catalyzed by this enzyme.     

The effects of temperature on ATPase activity and force generation in skinned muscle fibers from the Pacific blue marlin (Makaira nigricans)

Summary ATPase activity and force generation have been measured simultaneously in isolated, demembranated muscle fibers of the Pacific blue marlin (Makaira nigricans) between 0 and 30°C. Tension generation is relatively independent of temperature above 15°C and falls with a Q₁₀ of <1.5 on decreasing the temperature to 0°C. In contrast, the Q₁₀ for ATPase activity is 2.2 over the range 0–30°C. The results are interpreted in terms of the cross bridge theory of contraction.