Prolonged potentials in gastrointestinal muscles induced by calcium chelation

1977 ◽  
Vol 233 (1) ◽  
pp. C19-C24 ◽  
Author(s):  
C. L. Prosser ◽  
D. L. Kreulen ◽  
R. J. Weigel ◽  
W. Yau

When stomach muscles of skate, toad, or frog or intestinal muscle of cat are treated with Ca-free physiological solutions containing 2-5 mM EGTA or EDTA, spontaneous spikes and slow waves disappear reversibly. With continued treatment, depolarization of 25-30 mV from resting potentials of -65 mV occurs and rhythmic prolonged potentials of several seconds duration appear. They show rapid depolarization to near zero and rapid repolarization and they may continue for several hours. The prolonged potentials disappear when Na is replaced by Li, Tris, or choline. They are insensitive to TTX. The EGTA-induced waves are abolished by Mn, Co, La, verapamil, and D 600. After 10-15 min in 5 mM EGTA, voltage-current and abolition of anomalous rectification. It is concluded that when bound Ca is removed by a chelator, nonspecific reduction in resistance occurs and Na ions may enter rhythmically through channels normally used by Ca.

2004 ◽  
Vol 42 (06) ◽  
Author(s):  
M Storr ◽  
A Sibaev ◽  
J Schirra ◽  
D Weiser ◽  
O Kelber ◽  
...  
Keyword(s):  

2014 ◽  
Vol 26 (3-4) ◽  
pp. 42-61
Author(s):  
O. G. Lucyshyn ◽  
I. K. Teslenko

The recent ecological situation of Kyiv megalopolis has a special specific of environment technogenic pollution as a chemical features and content of polluting phytotoxicants. During 2007–2012, our observation revealed what the most dangerous factors which have harm impact on the street woody plants are the huge concentration of phytotoxic elements (Na+, Cl-, Pb2+, Cd2+). Nowadays, the technogenic impact on the megalopolyisis surrounding comes to the dangerous, even, catastrophic level. The main reason of total and chloral necrose of leaves, the summer defoliation of crown and major tree's death is the over pollution of the soil and plant's phytomass by phytotoxic elements, the concentration of which by standards evaluation and by trees reactions are critical and exists at the level of adaptation possibility and survival. The main sources of Pb2+ and Cd2+ ions are transport outcomes (> 90 % of total technogenic pollution). The increasing of Pb2+ and Cd2+ in the soil is depended from intensivity of transport outcomes, using of ethylated petrol, and location of trees along roads as well as from the trees species. Continuously increasing of number of cars at the city streets is accompanying with similar increasing of ions concentration. Thus, in the soil around root system of street woody plants, depending from their location along roads, the concentration of Pb2+ (moving form) is between 41,7 (I. Kudri str.) and 102,6 mg\kg of soil (Nauki avenue). It exceeds the maximum permissible concentration (MPC), which is 20,8–51,3 mg\kg of soil. Next, for Norway maple (Acer platanoides) the concentration of Pb2+ in the soil varies from 41,7 to 80,5 mg / kg of soil in the area of the root system and it is around 20,8–40,2 MPC. In the leaves of this tree it is 7,83–13,5 mg / kg of dry mass (MPC is 15,8–27,0). For the horse chestnut (Aedculus hippocastanum) at the Nauka avenue, the concentration of plumbum in the root is 13,4 mg / kg (MPC is 26,8), in the cortex – 17,7 mg / kg (MPC is 35,4), in leaves – 8,21 mg / kg (MPC is 16,4), which by the normative evaluation are the critical concentrations. The source of Na+ and Cl-, which is a new factor for Kyiv megalopolis, is irregular load of high concentrations of industrial salt NaCl into the environment, as a way against black ice in winter time, where the Na+ ions ( mobile form) is in the high concentrations in leaves (0,76 % for Norway maple (Acer platanoides) on the I. Kudri str., 1,28 % – small-leaved linden (Tilia cordata) at the 40-richya Zhovtnya ave, 2,0 % – horse chestnut (Aedculus hippocastanum) at the Nauki ave), those are exceeded the concentration of the element comparing to the control test object, respectively, in 10,6, 12,8 and 5,0 times. Na+ ions are an aggressive phytotoxins and the main factor of leaves necrose of tree crown (within 70–100 % necrosis leaves in the crown). Degradation and total reduction of the specific weight of plants in the megalopolis environment are decrease the cleaning role of the street tree plants, which are the main alive filters for soil and air cleaning, as well as the main bioaccumulators and detoxicants of harm substances of anthropogenic pollution. Species adaptive specificity is revealed at the bioaccumulation level and the selective locality of phytotoxic elements (Na+, Cl-, Pb2+, Cd2+, agile form) in technourbanhabitats-pic conditions, there dominated bioaccumulation and localization of Na+ ions by trees assimilative system is caused the adaptive orientation of endogenic and intraspecific variability of phytoindicative morphophysiologic features of plants functional condition under the stressing factors. This also is defined the sensitivity of small-leaved linden (Tilia cordata Mill.), norway maple (Acer platanoides L.) and horse chestnut (Aesculus hippocastanum L.) to the big concentration of potassium as the most danger one for the plant survival. The biggest accumulation of Na+ ions at the roots of Lombardy poplar (Populus pyramidalis Roz.), Bolle's poplar (Populus bolleana Lauche) and sugar maple (Acer saccharinum L.) is lead to a higher resistance of their assimilation system. At the technourbohabitate-pic conditions, the level of realization of ontogenetic and phylogenetic adaptive capacity of the sensitive species of trees is harmfully low (21,3–44,3 %). It is at the level of survival/death of plants. The street Lombardy poplar, Bolle's poplar and sugar maple, despite of more higher level of their adaptation (68,4–87,7 %), still also can't fully adapt to the critical levels of technogenic pollution of megalopolis environment. 


2020 ◽  
Vol 65 (6) ◽  
pp. 1058-1064
Author(s):  
С.В. Пастон ◽  
◽  
А.М. Поляничко ◽  
О.В. Шуленина ◽  
Д.Н. Осинникова ◽  
...  

The aqueous environment and ionic surrounding are the most important factors determining the conformation of DNA and its functioning in the cell. The specificity of the interaction between DNA and cations is especially pronounced with a decrease in water activity. In this work, we studied the B-A transition in high molecular weight DNA with a decrease of humidity in the film with different contents of Na+ ions using FTIR spectroscopy. The IR spectrum of DNA is not only very sensitive to the state of its secondary structure, but also allows us to estimate the amount of water bound to DNA. Upon dehydration of the DNA film, changes characteristic of the B-A transition were observed in the IR absorption spectrum. Using thermogravimetric analysis, it was shown that the degree of DNA hydration reaches the saturation level at a relative humidity of 60% and decreases slightly upon further drying. It has been established that with increasing Na+ concentration, the amount of water strongly bound to DNA decreases. Along with it, sodium ions destroy the hydration shell of DNA and are able to interact directly with phosphate groups.


1981 ◽  
Vol 46 (10) ◽  
pp. 2354-2363 ◽  
Author(s):  
Svatomír Kmošták ◽  
Karel Setínek

The catalytic activity of sulphonated macroporous styrene-divinylbenzene copolymers, the exchange capacity of which was neutralized from 30, 50 and 80% by Fe(III) ions and from 30% by Na ions and that of Wofatit Y-37 ion exchanger neutralized from 10% of its total exchange capacity by several transition metal ions and by sodium has been studied in isomerisation of cyclohexene and dehydration of 1-propanol in the gas phase at 130 °C. It was demonstrated that in both reactions transition metal ions exhibit additional effect to the expected neutralization of the polymer acid groups. In the case of cyclohexene isomerization, this effect depends on the degree of crosslinking of polymer mass of the catalyst. Such dependence has not been, however, observed in dehydration of 1-propanol. The type of transition metal ions did not exhibit any significant effect on the catalytic activity of the polymer catalysts studied.


1959 ◽  
Vol 197 (4) ◽  
pp. 829-834 ◽  
Author(s):  
Dana C. Brooks

The spontaneous electrical activity of the ventromedial nucleus was studied in the cat under pentobarbital anesthesia and in the unanesthetized, unrestrained state. Under light pentobarbital anesthesia the activity of the nucleus is characterized by a predominant 9–15 cps, 50–100 µv component which is uniform from second to second. With small additional doses of anesthesia there is a selective depression of this activity; with recovery from light anesthesia this activity is gradually replaced by irregular, large, slow waves characteristic of sleep. When the unanesthetized animal is aroused 20–35 cps activity having an amplitude of 40 µv or more appears in the nucleus. While the pattern of activity during sleep resembles that seen elsewhere in the hypothalamus, the activity seen during barbiturate anesthesia and during arousal is confined to the nucleus and not seen in other parts of the diencephalon.


SLEEP ◽  
2021 ◽  
Author(s):  
Brice V McConnell ◽  
Eugene Kronberg ◽  
Peter D Teale ◽  
Stefan H Sillau ◽  
Grace M Fishback ◽  
...  

Abstract Study Objectives Slow wave and spindle coupling supports memory consolidation, and loss of coupling is linked with cognitive decline and neurodegeneration. Coupling is proposed to be a possible biomarker of neurological disease, yet little is known about the different subtypes of coupling that normally occur throughout human development and aging. Here we identify distinct subtypes of spindles within slow wave upstates and describe their relationships with sleep stage across the human lifespan. Methods Coupling within a cross-sectional cohort of 582 subjects was quantified from stages N2 and N3 sleep across ages 6-88 years old. Results were analyzed across the study population via mixed model regression. Within a subset of subjects, we further utilized coupling to identify discrete subtypes of slow waves by their coupled spindles. Results Two different subtypes of spindles were identified during the upstates of (distinct) slow waves: an “early-fast” spindle, more common in stage N2 sleep, and a “late-fast” spindle, more common in stage N3. We further found stages N2 and N3 sleep contain a mixture of discrete subtypes of slow waves, each identified by their unique coupled-spindle timing and frequency. The relative contribution of coupling subtypes shifts across the human lifespan, and a deeper sleep phenotype prevails with increasing age. Conclusions Distinct subtypes of slow waves and coupled spindles form the composite of slow wave sleep. Our findings support a model of sleep-dependent synaptic regulation via discrete slow wave/spindle coupling subtypes and advance a conceptual framework for the development of coupling-based biomarkers in age-associated neurological disease.


Sign in / Sign up

Export Citation Format

Share Document