POTASSIUM MOVEMENTS IN RAT UTERUS STUDIED IN VITRO: I. EFFECTS OF TEMPERATURE

1963 ◽  
Vol 41 (10) ◽  
pp. 2065-2084 ◽  
Author(s):  
Edwin E. Daniel
Keyword(s):  
Extracellular Fluid ◽  
Muscle Layer ◽  
Exchange Constant ◽  
Extracellular Potassium ◽  
Longitudinal Muscle Layer ◽  
Potassium Balance ◽  
A Value ◽  
Temperature Loss ◽  
Water Accounting

1. Potassium movements have been studied in vitro in uteri of estrogenpretreated rats with42K as a tracer. At 37 °C the uterus was nearly in potassium balance in Krebs–Ringer bicarbonate and the exchange of potassium was adequately described by a single exchange constant, aside from a small fast fraction (17%) which probably contains potassium located superficially on cells as well as the extracellular potassium. No difference could be detected in their rates of exchange of potassium between two portions of the uterine horn, one containing only the longitudinal muscle layer and the other containing the remainder of the wall. The potassium exchange before or after flux correction for diffusion delay was about 5 or 9 moles cm−2sec−1, using a value of v/a of 1.8. There was a slow gain of sodium and water unrelated to potassium loss, attributed to expansion of the extracellular fluid.2. When the temperature of the Ringer fluid was reduced, the uterus remained in potassium balance at 27° and 17 °C. At 7 °C there was a net loss of potassium and exchange could no longer be described by one constant. On going from 37 to 7 °C the uterine horns shortened and the suggestion was made that muscle cells were depolarized initially by cold, or exuded water accounting for the rapidly exchanging fraction of potassium observed at this temperature. Loss of radioactive potassium from the myometrium owing to depolarization and associated with contraction appeared to account for the inhomogeneity on going to 7 °C. The Q10for influx of potassium between 27 and 7 °C was about 3 while that for efflux was about 1.6, excluding the fast fraction present at low temperatures. The Q10for efflux was diminished by depolarization and that for influx increased so that both may have been about 2. When uterine horns were stored overnight in the cold, they lost potassium and gained sodium, chloride, and water, but these ion changes were reversed on rewarming.

POTASSIUM MOVEMENTS IN RAT UTERUS STUDIED IN VITRO: I. EFFECTS OF TEMPERATURE

1963 ◽  
Vol 41 (1) ◽  
pp. 2065-2084 ◽  
Author(s):  
Edwin E. Daniel
Keyword(s):  
Extracellular Fluid ◽  
Muscle Layer ◽  
Exchange Constant ◽  
Extracellular Potassium ◽  
Longitudinal Muscle Layer ◽  
Potassium Balance ◽  
A Value ◽  
Temperature Loss ◽  
Water Accounting

1. Potassium movements have been studied in vitro in uteri of estrogenpretreated rats with42K as a tracer. At 37 °C the uterus was nearly in potassium balance in Krebs–Ringer bicarbonate and the exchange of potassium was adequately described by a single exchange constant, aside from a small fast fraction (17%) which probably contains potassium located superficially on cells as well as the extracellular potassium. No difference could be detected in their rates of exchange of potassium between two portions of the uterine horn, one containing only the longitudinal muscle layer and the other containing the remainder of the wall. The potassium exchange before or after flux correction for diffusion delay was about 5 or 9 moles cm−2sec−1, using a value of v/a of 1.8. There was a slow gain of sodium and water unrelated to potassium loss, attributed to expansion of the extracellular fluid.2. When the temperature of the Ringer fluid was reduced, the uterus remained in potassium balance at 27° and 17 °C. At 7 °C there was a net loss of potassium and exchange could no longer be described by one constant. On going from 37 to 7 °C the uterine horns shortened and the suggestion was made that muscle cells were depolarized initially by cold, or exuded water accounting for the rapidly exchanging fraction of potassium observed at this temperature. Loss of radioactive potassium from the myometrium owing to depolarization and associated with contraction appeared to account for the inhomogeneity on going to 7 °C. The Q10for influx of potassium between 27 and 7 °C was about 3 while that for efflux was about 1.6, excluding the fast fraction present at low temperatures. The Q10for efflux was diminished by depolarization and that for influx increased so that both may have been about 2. When uterine horns were stored overnight in the cold, they lost potassium and gained sodium, chloride, and water, but these ion changes were reversed on rewarming.

In vitro microelectrode study of the electrical properties of smooth muscle in equine ileum

2001 ◽  
Vol 149 (23) ◽  
pp. 707-711 ◽  
Author(s):  
N. P. H. Hudson ◽  
I. G. Mayhew ◽  
G. T. Pearson
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Longitudinal Muscle ◽  
Muscle Cells ◽  
Muscle Layer ◽  
Potential Oscillations ◽  
Longitudinal Muscle Layer ◽  
Membrane Potential Oscillations

Intracellular microelectrode recordings were made from smooth muscle cells in cross-sectional preparations of equine ileum, superfused in vitro. Membrane potential oscillations and spike potentials were recorded in all preparations, but recordings were made more readily from cells in the longitudinal muscle layer than from cells in the circular layer. The mean (se) resting membrane potential (RMP) of smooth muscle cells in the longitudinal muscle layer was -51.9 (1.2) mV, and the membrane potential oscillations in this layer had a mean amplitude of 4.8 (0.4) mV, a frequency of 9.0 (0.1) cycles per minute and a duration of 5.8 (0.2) seconds. The membrane potential oscillations were preserved in the presence of tetrodotoxin. A waxing and waning pattern of membrane potential oscillation activity was observed. Nifedipine abolished the spiking contractile activity of the smooth muscle, did not abolish the membrane potential oscillations but did alter their temporal characteristics.

Longitudinal contractions in the duodenum: their fluid-mechanical function

1975 ◽  
Vol 228 (6) ◽  
pp. 1887-1892 ◽  
Author(s):  
J Melville ◽  
E Macagno ◽  
J Christensen
Keyword(s):  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Slow Waves ◽  
Longitudinal Muscle Layer ◽  
Circular Muscle Layer ◽  
Model Flow ◽  
Displacement Wave ◽  
Marked Points

The hypothesis examined was that contractions of the longitudinal muscle layer occurin the duodenum which are independent of those of the circular muscle layer and that they induce flow of duodenal contents. A segment of opossum duodenum isolated in vitro was marked and photographed during periods of longitudinal muscle contraction, when the circular muscle layer appeared inactive. The prequency of longitudinal oscillation of the marked points was 20.5 cycles/min. The longitudinal displacement wave spread caudad with an average velocity of 3.27 cm/s. Frequency and velocity of electrical slow waves were determined in similiar duodenal segments. Slow-wave frquencywas 18.9 cycles/min. In a two-dimensional mechanical model, flow induced by simulatedlongitudinal muscle layer appear to be driven by the electrical slow waves of the duodenum. They are capable of inducing a pattern of flow in which ocntents flow betweenthe core and the periphery of the intestinal conduit.

A nitric oxide and prostaglandin-dependent component of NANC off-contractions in cat colon

1994 ◽  
Vol 266 (1) ◽  
pp. G40-G47 ◽  
Author(s):  
K. Venkova ◽  
J. Krier
Keyword(s):  
Electrical Field Stimulation ◽  
Distal Colon ◽  
Muscle Layer ◽  
No Synthase ◽  
Longitudinal Muscle Layer ◽  
Mechanical Responses ◽  
Dependent Component ◽  
Significant Depression ◽  
Spontaneous Contractions

The actions of NO synthase inhibitors and indomethacin, a cyclooxygenase inhibitor, on the nonadrenergic noncholinergic (NANC) mechanical responses of cat distal colon were studied in vitro using muscle strips orientated in the axis of the longitudinal muscle layer with pelvic nerves attached. Electrical field stimulation (EFS) or pelvic nerve stimulation (PNS) caused inhibition of spontaneous contractions followed by off-contractions. Indomethacin (10-30 microM) caused concentration-dependent reductions in amplitude and duration of EFS- and PNS-evoked off-contractions but not latency. The NO synthase inhibitors, N omega-nitro-L-arginine (L-NNA), N omega-nitro-L-arginine methyl ester (L-NAME) and NG-monomethyl-L-arginine (L-NMMA) (each at 100 microM) significantly reduced latency, amplitude, and duration of off-contractions evoked by EFS and PNS. This inhibition was partially reversed by L-arginine (120 microM) but not by D-arginine. Incubation of colonic strips with alpha-chymotrypsin (2 U/ml) decreased latency, amplitude, and duration of NANC off-contractions. L-NNA reduced amplitude, duration, and latency of off-contractions in preparations pretreated with alpha-chymotrypsin. Hydroquinone (10-30 microM), a generator of superoxide anions, caused significant depression of amplitude, duration, and latency of off-contractions which was completely reversed by superoxide dismutase (200 U/ml). These data suggest that the components of NANC off-contractions evoked by EFS and PNS involve peptides, NO, and prostaglandins.

POTASSIUM MOVEMENTS IN RAT UTERUS STUDIED IN VITRO: II. EFFECTS OF METABOLIC INHIBITORS, OUABAIN, AND ALTERED POTASSIUM CONCENTRATIONS

1963 ◽  
Vol 41 (10) ◽  
pp. 2085-2105 ◽  
Author(s):  
Edwin E. Daniel
Keyword(s):  
Extracellular Fluid ◽  
Flux Ratio ◽  
Dry Weight ◽  
Membrane Potentials ◽  
Metabolic Inhibitors ◽  
Rat Tissues ◽  
Rat Uterus ◽  
Longitudinal Muscle Layer ◽  
Exchange Diffusion

1. Sodium fluoride (10−2 M), 2,4-dinitrophenol (10−4 M), and iodoacetate (10−4 M) caused a slight decrease in potassium uptake by the uterus and fluoride and dinitrophenol caused a larger and immediate increase in efflux, resulting in a net loss of potassium. There was apparently a delayed increase in efflux caused by iodoacetate. The effects of inhibitors on efflux were not prevented by the absence of external potassium. The effects of fluoride suggested that it produced inhomogeneity in uterine potassium and analysis of the longitudinal muscle layer separately from the remainder of the uterus suggested that efflux was speeded more in myometrium than in endometrium. This was attributed to the prolonged contracture induced by fluoride. The depolarization required to explain the increases in efflux produced by fluoride and DNP was sufficient to explain the decreases in influx. It was postulated that these inhibitors act by causing depolarization which might be the result of inhibition of an electrogenic sodium pump. Iodoacetate 10−3 M caused a 50% reduction in potassium influx and probably a large immediate increase in efflux, but no evidence was obtained that this concentration caused contraction.2. Ouabain in concentrations as high as 10−5 M had only minor effects on potassium inward and outward movements and on reaccumulation of potassium and extrusion of sodium during recovery from exposure to the cold. The resistance of rat uteri to cardiac glycosides derives either from insensitivity in rat tissues or from a unique feature of sodium transport in the rat uterus.3. When KCl was added to the Ringer fluid, there was no net gain of cellular potassium relative to dry weight. Osmotic balance was achieved mainly by water loss from cells, but uncertainty as to the extracellular fluid volume prevented a definite conclusion. When KCl was omitted from the Ringer fluid, there was a 50% decrease in efflux, suggesting that a part of the potassium movement was "exchange diffusion". The assumption of exchange diffusion also would aid in explaining the observed flux ratio near unity in view of the values reported for membrane potentials of uterine cells. Owing to the lack of data regarding intracellular activity of potassium and the incompleteness of data on membrane potentials of uterine cells, it was not possible to prove whether active influx of potassium was present or absent in addition to that entering passively either by free diffusion or exchang diffusion.

Coordination of electrical activities in muscle layers of the pig colon

1987 ◽  
Vol 252 (1) ◽  
pp. G136-G142
Author(s):  
J. D. Huizinga ◽  
E. Chow ◽  
N. E. Diamant ◽  
T. Y. el-Sharkaway
Keyword(s):  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Simultaneous Recording ◽  
Frequency Range ◽  
Longitudinal Muscle Layer ◽  
Circular Muscle Layer ◽  
High Level ◽  
Electrical Activities

Simultaneous recording of electrical activities from the circular and longitudinal muscle layers of the pig colon was performed in vitro to study possible coordination of activities. The electrical activity of both muscle layers consisted of electrical oscillations with superimposed spikes. The frequency range of the electrical oscillations in the circular muscle was 0.5-3.5 cycles per minute (cpm) and in the longitudinal muscle 24-42 cpm. Coordination of the activities of both muscle layers occurred consistently only after stretch or cholinergic stimulation. Then it occurred in a unique fashion. Each oscillation in the circular muscle layer occurred at the same time as the onset of a burst of oscillations in the longitudinal muscle. In addition, multiple simultaneous recordings of the electrical activities from each muscle layer were obtained showing that within the circular muscle layer electrical oscillations were phase locked in the circumferential direction and along the long axis of the colon. They appeared to propagate in either the oral or aboral direction. In tetrodotoxin (with stretch as stimulus) and also in presence of carbachol, bursts of oscillations in the longitudinal muscle layer were phase locked circumferentially (in the different taeniae) and longitudinally. This study shows that the muscle layers in the colon, which have different myogenic electrical activities, can obtain a high level of coordination.

scholarly journals Patterns of intracellular and intercellular Ca 2+ waves in the longitudinal muscle layer of the murine large intestine In vitro

2002 ◽  
Vol 543 (1) ◽  
pp. 233-253 ◽  
Author(s):  
Grant W. Hennig ◽  
Christian B. Smith ◽  
Deirdre M. O'Shea ◽  
Terence K. Smith
Keyword(s):  
Large Intestine ◽  
Longitudinal Muscle ◽  
Muscle Layer ◽  
Longitudinal Muscle Layer

POTASSIUM MOVEMENTS IN RAT UTERUS STUDIED IN VITRO: II. EFFECTS OF METABOLIC INHIBITORS, OUABAIN, AND ALTERED POTASSIUM CONCENTRATIONS

1963 ◽  
Vol 41 (1) ◽  
pp. 2085-2105 ◽  
Author(s):  
Edwin E. Daniel
Keyword(s):  
Extracellular Fluid ◽  
Flux Ratio ◽  
Dry Weight ◽  
Membrane Potentials ◽  
Metabolic Inhibitors ◽  
Rat Tissues ◽  
Rat Uterus ◽  
Longitudinal Muscle Layer ◽  
Exchange Diffusion

1. Sodium fluoride (10−2 M), 2,4-dinitrophenol (10−4 M), and iodoacetate (10−4 M) caused a slight decrease in potassium uptake by the uterus and fluoride and dinitrophenol caused a larger and immediate increase in efflux, resulting in a net loss of potassium. There was apparently a delayed increase in efflux caused by iodoacetate. The effects of inhibitors on efflux were not prevented by the absence of external potassium. The effects of fluoride suggested that it produced inhomogeneity in uterine potassium and analysis of the longitudinal muscle layer separately from the remainder of the uterus suggested that efflux was speeded more in myometrium than in endometrium. This was attributed to the prolonged contracture induced by fluoride. The depolarization required to explain the increases in efflux produced by fluoride and DNP was sufficient to explain the decreases in influx. It was postulated that these inhibitors act by causing depolarization which might be the result of inhibition of an electrogenic sodium pump. Iodoacetate 10−3 M caused a 50% reduction in potassium influx and probably a large immediate increase in efflux, but no evidence was obtained that this concentration caused contraction.2. Ouabain in concentrations as high as 10−5 M had only minor effects on potassium inward and outward movements and on reaccumulation of potassium and extrusion of sodium during recovery from exposure to the cold. The resistance of rat uteri to cardiac glycosides derives either from insensitivity in rat tissues or from a unique feature of sodium transport in the rat uterus.3. When KCl was added to the Ringer fluid, there was no net gain of cellular potassium relative to dry weight. Osmotic balance was achieved mainly by water loss from cells, but uncertainty as to the extracellular fluid volume prevented a definite conclusion. When KCl was omitted from the Ringer fluid, there was a 50% decrease in efflux, suggesting that a part of the potassium movement was "exchange diffusion". The assumption of exchange diffusion also would aid in explaining the observed flux ratio near unity in view of the values reported for membrane potentials of uterine cells. Owing to the lack of data regarding intracellular activity of potassium and the incompleteness of data on membrane potentials of uterine cells, it was not possible to prove whether active influx of potassium was present or absent in addition to that entering passively either by free diffusion or exchang diffusion.

scholarly journals Characterization of the SARS-CoV-2 coronavirus X4-like accessory protein

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Olanrewaju Ayodeji Durojaye ◽  
Nkwachukwu Oziamara Okoro ◽  
Arome Solomon Odiba
Keyword(s):  
Rapid Development ◽  
Protein A ◽  
The Novel ◽  
Quality Model ◽  
A Value ◽  
Model Protein ◽  
Novel Coronavirus ◽  
Global Threat

Abstract Background The novel coronavirus SARS-CoV-2 is currently a global threat to health and economies. Therapeutics and vaccines are in rapid development; however, none of these therapeutics are considered as absolute cure, and the potential to mutate makes it necessary to find therapeutics that target a highly conserved regions of the viral structure. Results In this study, we characterized an essential but poorly understood coronavirus accessory X4 protein, a core and stable component of the SARS-CoV family. Sequence analysis shows a conserved ~ 90% identity between the SARS-CoV-2 and previously characterized X4 protein in the database. QMEAN Z score of the model protein shows a value of around 0.5, within the acceptable range 0–1. A MolProbity score of 2.96 was obtained for the model protein and indicates a good quality model. The model has Ramachandran values of φ = − 57o and ψ = − 47o for α-helices and values of φ = − 130o and ψ = + 140o for twisted sheets. Conclusions The protein data obtained from this study provides robust information for further in vitro and in vivo experiment, targeted at devising therapeutics against the virus. Phylogenetic analysis further supports previous evidence that the SARS-CoV-2 is positioned with the SL-CoVZC45, BtRs-BetaCoV/YN2018B and the RS4231 Bat SARS-like corona viruses.

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