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PubMed1975

Synaptic changes in frog brain after stimulation with potassium chloride.

In vitro preparations of frog brains, stimulated by application of CKl were fixed by freeze substitution and examined electron microscopically. Control preparations were bathed in a calcium-free physiological solution with Mg added or in salt solution cooled to 5-10-degrees C. The isolated brain remains viable in the physiological solution as indicated by the direct cortical responses which can be led off from the forebrain. Control preparations were characterized by a row of vesicles situated close to the presynaptic membrane and by the absence of a well-developed postsynaptic web. In KCl stimulated preparations there were, in addition to synapses resembling those in the controls, synapses exhibiting fusion of synaptic vesicles with the membrane of the axonal ending, synapses in which the vesicles had retreated from the presynaptic membrane but were attached to it by a narrow stalk and synapses exhibiting a pronounced postsynaptic web. The synaptic gap was of a less uniform width than in the control preparations. The KCl stimulated preparations were furthermore characterized by a paucity of extracellular space and often showed invaginations formed by the presynaptic membrane and the plasma membranes of the postsynaptic or adjacent glial structure.

Animals↗

PubMed1984

Protein synthesis studies in skeletal muscle of aging rats. II. In vitro studies with 0.5M potassium chloride washed polyribosomes.

To investigate further the age-related reduction in muscle protein synthesis activity found previously using a crude polyribosome/pH 5 system (Pluskal et al., 1984), a 0.5M KCl washing procedure was utilized to remove the nonribosomal factors from polyribosomes isolated from male Sprague-Dawley rats in the following age groups: young (1 to 2 months), mature (12 months), and aged (22 to 24 months). Using a common source of enriched elongation factor fraction from young animals, it was not possible to demonstrate any significant difference (p greater than .05) in protein synthesis between the 0.5M KCl-washed polyribosomes isolated from the various age groups. Using a cell-free system containing young salt washed polyribosomes stimulated by the addition of 0.5M KCl-wash fractions, however, it was shown that the mature and aged salt-wash fractions were less (p less than .05) active than material from young animals. Thus, the observed decline in protein synthesis efficiency during aging may be attributed to a reduced capacity to promote initiation/elongation by the nonribosomal salt wash fractions of muscle polyribosomes.

Aging↗

PubMed1983

Potassium chloride- and norepinephrine-induced contractile responses in rabbit pulmonary blood vessels.

Responses to KCl and norepinephrine (NE) were examined with ring segments of right extrapulmonary artery, intrapulmonary artery and intrapulmonary vein isolated from rabbit lung. From concentration-response curves to KCl, optimal applied loads were determined to be 5 g for right extrapulmonary artery and intrapulmonary artery and 500 mg for intrapulmonary vein. Both individual and cumulative concentration-response curves to KCI and NE were performed. All gave reproducible results; however, tissues were more sensitive to cumulative addition of either contractile agent. Of three successive cumulative NE concentration-response curves, second and third curves were most reproducible in relation to both sensitivity to NE and maximal force development. Cumulative NE concentration-response curves also exhibited a triphasic pattern, consisting of an initial contractile response (10(-10) to 10(-6) M NE) followed by relaxation or reversal of contractile force development (10(-6) to 10(-4) M NE), then a second contractile response at concentrations of NE greater than 10(-4) M. This response pattern was most prominent in intrapulmonary vessels and was absent in rabbit aorta.

Animals↗

PubMed1998

Potassium chloride inhibits proliferation of cerebellar granule neuron progenitors.

CNS neurogenesis involves a critical transition where neuronal progenitors exit the cell cycle and initiate terminal differentiation. Recent experiments have suggested that depolarization inhibits DNA synthesis in cortical progenitors. Depolarization of proliferating neuronal progenitors may thus activate mechanisms that prevent proliferation and allow the initiation of terminal differentiation. We present evidence that depolarizing concentrations of KCl (25-50 mM) reduce proliferation of developing postnatal cerebellar granule cells in culture. These studies show that KCl antagonizes the mitogenic response of granule cells to insulin-like growth factor-I (IGF-I) and that this reduction in proliferating cells is not the result of a selective cell death. We also examined the differentiation of granule cell cultures using Brn-5 expression as an early differentiation marker. In vivo Brn-5 expression occurs soon after developing granule cells exit the cell cycle and begin their final differentiation. In control cultures and cultures treated with high concentrations of KCl Brn-5 expression increased over 24-48 h of culture. Our results suggest depolarizing concentrations of KCl antagonize proliferation of cerebellar granule neuron progenitors however allow their continued differentiation.

Animals↗

PubMed1996

Potassium chloride pulse enhances mitogen-activated protein kinase activity in rat hippocampal slices.

Mitogen-activated protein (MAP) kinases have been implicated in multiple responses to extracellular stimuli. In this study we show that MAP kinase activity is enhanced after a KCl pulse. This activation correlates with an increased tyrosine phosphorylation of a 42-kDa protein as determined by antiphosphotyrosine immunoblot. The same band is found in an anti-MAP kinase immunoblot. Activity is enhanced within 1 min, reaches a maximum at 2 min, and returns to basal level after 10 min. A second peak of activity is observed between 12 and 30 min. The activation is completely blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), showing the involvement of the AMPA type of glutamate receptor. Partial inhibition of MAP kinase activation by 2-amino-5-phosphonovalerate (APV) also shows the involvement of the NMDA receptor. Because the KCl pulse used induces long-term potentiation (LTP) in rat hippocampal slice, we conclude that MAP kinase may be involved in neuronal transduction events leading to LTP.

2-Amino-5-phosphonovalerate↗

PubMed1999

[The determination of the coagulation threshold of the electrolyte potassium chloride in human mixed saliva].

For quantitative assessment of the stability of dispersed phase corpuscles in the gingival fluid, coagulation threshold and coagulating effect of electrolyte KCl were studied in salivary pools of caries-resistant (CR) and caries-liable (CL) subjects by the optic method widely used for investigation of pure colloid systems. Test samples were prepared by mixing certain volumes of saliva, distilled water, and KCl. Light absorbance was measured by photoelectrocolorimetry on a MKMF-1 device and pH was measured by the potentiometric method using pH-121 device. Coagulation threshold and coagulating effect of the electrolyte were estimated using the graphic method. The saliva of both CR and CL subjects generally follows the regularities typical of pure colloid systems. KCl coagulation threshold of CR subjects' saliva is higher than of subjects with caries, while its coagulating effect is higher in the CL group. Dispersed phase corpuscles in the saliva of CR subjects are more stable than in subjects with caries. These results may be used in development of quantitative methods for assessing the stability of salivary dispersed phase corpuscles and salivary mineralizing capacity in subjects with different oral status.

Colloids↗

PubMed1977

Self-assembly of myosin in vitro caused by rapid dilution. Effects of hydrogen ion, potassium chloride, and protein concentrations.

The in vitro assembly of rabbit skeletal myosin was studied by flow birefringence. Filaments were obtained from a solution of myosin in 0.5 M KCl by rapid dilution to lower ionic strength. In most cases, the filament length as determined from extinction angle measurements increased or decreased gradually for about 1 h after dilution, depending on pH, KCl concentration and the previous history. The filament length (l) immediately after dilution also showed a marked dependence on pH, KCl concentration and protein concentration (c) at the moment of assembly. The general characteristics obtained from our limited study (0.04-6.0 mg/ml) show three distinctive modes of effect of the protein concentration on the filament length: d logl/d log c is positive (0.1-1) at small c, negative (from -1 to -0.2) at intermediate c, and zero or slightly positive (0.0-0.3) at large c. Lowering of the KCl concentration (75-250 mM) as well as increase of the hydrogen ion concentration (pH 6-8) influenced the filament length in qualitatively the same manner as increase of the protein concentration. A model of the assembly reaction of myosin in which the polarity of filaments is crucial was constructed and shown to give qualitatively the experimental dependence of the filament length on the protein concentration.

Animals↗

PubMed1991

Effect of potassium chloride on cytosolic calcium of brain synaptosomes of rats with chronic renal failure.

Norepinephrine (NE) release from brain synaptosomes is dependent in major part on an adequate rise in cytosolic calcium ([Ca2+]i). A smaller or a greater calcium signal (delta [Ca2+]i) or delta[Ca2+]i/basal [Ca2+]i ratio in response to stimuli may interfere with NE release from brain synaptosomes. In order to further evaluate the mechanism of reduced NE release from brain synaptosomes in chronic renal failure (CRF), we examined the changes in synaptosomal [Ca2+]i in response to KCl in normal, CRF, and normocalcemic, parathyroidectomized (PTX) CRF rats (CRF-PTX) and in CRF rats treated with verapamil (CRF-V). CRF rats displayed significantly (p less than 0.01) higher basal levels of [Ca2+]i and a higher delta[Ca2+]i and delta [Ca2+]i/basal [Ca2+]i ratio than in the other three groups of rats. These parameters were not different among normal, CRF-PTX and CRF-V rats. The data are consistent with the notion that the higher calcium signal and the higher ratio between signal and the basal [Ca2+]i in response to a stimulus in CRF are deleterious to synaptosomal function and are responsible, in part, for the reduced NE release by these structures in CRF.

Animals↗

PubMed2001

Altered contractions to endothelin-1, phenylephrine, potassium chloride and relaxations to acetylcholine at various stages of renal hypertension in the rat.

This study is aimed at investigating the contraction and relaxation responses in the thoracic and abdominal aortae at various stages of hypertension. Hypertension in the rats was produced by aortic banding and the responses in the abdominal and thoracic aortic rings were studied 2 and 8 weeks after aortic banding. Contractile responses to phenylephrine ( 10(-6)M), KCl (80 mM) or to endothelin-1 ( 10(-12)to 10(-6)M) and the relaxation responses to acetylcholine ( 10(-7)to 10(-5)M) were similar in the thoracic and abdominal rings of normotensive rats. The intact thoracic rings from 2 week aortic-banded hypertensive rats (ABHR) showed attenuated responses to all the contractile agents used. However, the relaxation to acetylcholine was not altered. In the rings from 8 week ABHR, the responses to contractile agents were not significantly altered but the acetylcholine-induced relaxations were significantly attenuated. The endothelial-derived relaxing factors might act to antagonize the vasoconstrictive responses during the onset of hypertension but might be disabled, as the endothelial dysfunction becomes predominant after 8 weeks of hypertension. The results thus suggest that the contractile and relaxant responses are differentially altered during different stages of hypertension.

Acetylcholine↗

PubMed1996

Interleukin-1 beta decreases sensitivity of guinea-pig airway to potassium chloride and isoproterenol by an epithelium-dependent mechanism.

Airway inflammation may cause alteration of airway responses in chronic airway diseases, such as bronchial asthma. The objective of this study was to examine whether interleukin-1beta (IL-1beta) [corrected], one of the pro-inflammatory cytokines, has a direct effect on airway functions. The effects of IL-1beta on carbachol, KCl and isoproterenol (ISO) responses of isolated guinea-pig tracheal strips were examined by measuring isometric tension in tissue bath. Responses of tracheal strips with or without epithelium to each agonist were compared before and after incubation with IL-1beta (25 ng or 250 ng/mL). Both 1 h and 5 h incubation of the strips with 250 ng/mL IL-1beta significantly decreased the sensitivity not only to KCl (P < 0.05; P < 0.01, respectively), but also to ISO (both P < 0.05) without affecting maximum contraction or relaxation. Response to carbachol was not affected by IL-1beta. Epithelial denudation abolished the effects of IL-1beta on KCl and ISO responses. Indomethacin (2 micromol/L) [corrected] reversed the effects of IL-1beta both on KCl and on ISO. These results suggest that IL-1 beta decreases the sensitivity of airway strips to KCl and ISO, possibly by stimulating prostaglandin production from the airway epithelium [corrected].

Animals↗

PubMed1976

The effect of temperature on potassium chloride contracture in cat myocardium.

1. Contracture was induced in cat myocardium by exposure to 140 mM-KC1 In isotonic Tyrode solution. Force of contracture expressed as mg/mm2 (muscle cross-sectional area) falls with increasing cross-sectional area. 2. The effect of temperature on isometric force developed during contracture was evaluated both in normal (untreated) atrial and ventricular muscle and following treatment with sympatholytic drugs. 3. The force of contracture was not significantly affected by sympatholytic drugs at 36 degrees C. 4. In normal atrial and ventricular muscle, force of contracture decreased when the muscle was cooled from 36 to either 29 or 20 degrees C. 5. In atrial muscle, the effect of temperature was not changed by sympatholytic drugs. In contrast, exposure to sympatholytic drugs increased contracture force developed by ventricular muscle at 20 degrees C. Also, contracture force was significantly greater at 20 than at 36 degrees C in ventricular muscle from reserpine-pretreated cats. 6. It is suggested that ventricular muscle becomes more sensitive to the relaxing effects of endogenous catecholamines at temperature is lowered. 7. The differences shown between atrial and ventricular muscle with respect to the effect of temperature and sympatholytic drugs on contracture force may result from the differing amounts of sarcoplasmic reticulum found in these types of cardiac muscle and also from different mechanisms of "excitation-contracture" coupling in atrial and ventricular muscle.

Animals↗

PubMedDate not supplied

Insulin release from pancreatic islets of fetal rats mediated by leucine b-BCH, tolbutamide, glibenclamide, arginine, potassium chloride, and theophylline does not require stimulation of Ca2+ net uptake.

In pancreatic islets of fetal rats the effect of glucose (3 and 16.7 mM), glyceraldehyde (10 mM), leucine (20 mM), b-BCH (20 mM), tolbutamide (100 micrograms/ml), glibenclamide (0.5 and 5.0 micrograms/ml) arginine (20 mM), KCl (20 mM) and theophylline (2.5 mM) on 45Ca2+ net uptake and secretion of insulin was studied. All compounds tested failed to stimulate 45Ca2+ net uptake. However, in contrast to glucose and glyceraldehyde, leucine, b-BCH, tolbutamide, glibenclamide, arginine, KCl and theophylline significantly stimulated release of insulin. This effect could not be inhibited by the calcium antagonist verapamil (20 microM). Elevation of the glucose concentration from 3 to 5.6 mM did not alter 86Rb+ efflux of fetal rat islets but inhibited 86Rb+ efflux of adult rat islets. Stimulation of 86Rb+ efflux with tolbutamide (100 micrograms/ml), leucine (20 mM) or b-BCH (20 mM) in the presence of 3 mM glucose was also ineffective in fetal rat islets. Our data suggest that stimulation of calcium uptake via the voltage dependent calcium channel is not possible in the fetal state. They also provide evidence that stimulators of insulin release which are thought not to act through their metabolism, initiate insulin secretion from fetal islets by a mechanism which is different from stimulation of calcium influx.

Amino Acids↗

PubMed1989

Responses of small intrapulmonary arteries to vasoactive compounds in the fetal and neonatal lamb: norepinephrine, epinephrine, serotonin, and potassium chloride.

Despite considerable study, the mechanisms responsible for the transition of the pulmonary circulation from the fetal to newborn life remain obscure. We compared the responses of third and fourth generation pulmonary arteries to norepinephrine, epinephrine, serotonin, and KCl from lambs 7 d preterm and 1, 7, and 21 d of age to assess differences between age and third and fourth generations of the pulmonary arterial tree during the transitional period. Preterm vessels were significantly smaller in internal diameter than all other aged vessels for both generations. Fourth generation vessel response to KCl increased with age (94 +/- 15 mg/mm2, preterm; 259 +/- 31 mg/mm2, 21 d). Third generation vessel response to KCl did not change with age (135 +/- 15 mg/mm2, preterm; 158 +/- 18 mg/mm2, 21 d). There were no differences in maximum response to norepinephrine and epinephrine between ages; however, third generation vessel response to these compounds was significantly greater (30-60% of maximum KCl response) than fourth generation vessel response (0-10%). Third and fourth generation vessels had the same maximum response to serotonin regardless of age or generation. Third generation vessels were significantly reduced in sensitivity (log molar concentration which produced 50% of the maximum response--EC50) to norepinephrine at d 1 (5.89 +/- 0.12 log molar) and 7 (5.90 +/- 0.21) compared to preterm (6.48 +/- 0.10) and 21 d of age (6.50 +/- .03).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1977

Inhibition of leucocyte migration by potassium chloride extracts of human tumor cells in ascites and from tissues.

Human gastric cancer-associated antigens were solubilized from fresh ascites and surgical specimens by 3M KCl extraction. The antigenicity of these extracts was measured by leucocyte migration inhibition assay with an improved modification devised in this laboratory. Antigens extracted mutually reacted with autologous and allogeneic leucocytes taken from cancer patients. The out of 11 (27%) patients and 7 out of 28 (25%) patients with various cancers showed positive migration index values against 13 ascites tumor cell antigens in the autologous and allogeneic reaction systems, respectively. Reactions were positive in 4 out of 10 patients with gastric cancer against autologous antigens, and in 10 out of 26 (38%) of the patients against allogeneic tumor antigens. On the other hand, one patient with gastric cancer reacted well with various sources of antigens extracted from allogeneic cells of gastric cancer, while the other patient with gastric cancer did not react with any of five gastric cancer antigens tested so far. These findings suggested that the cell-mediated immune response of patients with gastric cancer against autologous and allogeneic tumor antigens extracted was detectable in the test system. It is considered at present that the eM KCl antigen may be relate to human leucocyte antigen, and some common antigenic reactants capable of reacting with several gastric cancer may be involved in this reaction.

Antigens, Neoplasm↗

PubMed1980

Effects of pyrophosphate, triphosphate, and potassium chloride on adenylate deaminase from rat muscle.

Inorganic pyrophosphate and triphosphate inhibit adenylate deaminase from rat skeletal muscle with K1 values of 10 and 1.5 microM, respectively, in the presence of 150 mM KCl at pH 7. They act by reducing the apparent affinity of the enzyme for AMP, with relatively small effects on Vmax. The inhibitions are diminished by H+, the KI values increasing two- to threefold in going from pH 7.0 to 6.2, and are relieved by ADP. These properties are similar to the inhibitions produced by GTP and ATP, indicating that pyrophosphate and triphosphate act like analogues of the nucleoside triphosphates. Neither of these inhibitors shows relief of inhibition at high concentrations as do ATP and GTP. These results suggest that nucleotides interact with the inhibitor site of the enzyme primarily through their phosphate moieties and with the activator site primarily through their nucleoside moieties. As the concentration of KCl is increased from 25 to 300 mM, the apparent affinities of the enzyme for ATP, GTP, orthophosphate, pyrophosphate, and triphosphate are decreased 8-100-fold. The cooperativity of the inhibitions is increased with the Hill coefficient rising from 1.0 to 1.3-1.8, and the maximum inhibition approaches 100%. Maximum activation by ADP is reduced from 1800% at 25 mM KCl to 80% at 200 mM KCl. Experiments with (CH3)4NCl indicate that activation of the enzyme by KCl involves both specific K+ effects and ionic strength effects.

AMP Deaminase↗

PubMed1997

Cortical application of potassium chloride induces the low-molecular weight heat shock protein (Hsp27) in astrocytes.

Spreading depression induces tolerance to ischemic injury, and ischemic tolerance has been associated with expression of heat shock proteins (Hsp). Here we examine Hsp27 expression after KCl-induced spreading depression. Twenty-minute cortical KCl application induced Hsp27 immunoreactivity in glial fibrillary acidic protein-positive astrocytes of the ipsilateral neocortex. Systemic administration of MK-801 (3 mg/kg) suppressed KCl-induced Hsp27 expression in the parietal cortex. Astrocytes in the posterior cingulate and retrosplenial cortex did not express Hsp27 after KCl application but did express Hsp27 after systemic administration of high dose MK-801 (9 mg/kg). Whereas Hsp27 was usually observed in all layers of the parietal cortex after 5-minute application of KCl, in 2 of 6 rats, Hsp27 was seen in clusters of astrocytes or in astrocytes in the superficial layers I to III of the parietal cortex. We conclude that (1) cortical application of KCl triggered Hsp27 astrocytic expression; (2) astrocytes in the cingulate and retrosplenial cortex responded differently compared with astrocytes of the parietal cortex; (3) Hsp27 expression progressed from small clusters of astrocytes throughout superficial layers of the cortex that joined and recruited astrocytes in deeper layers; (4) several mechanisms induced Hsp27 astrocytic expression. We propose that Hsp27 is involved in spreading depression-induced ischemic tolerance through protection of astrocyte function.

Animals↗

PubMed1979

Influence of potassium chloride upon the binding and antibacterial activity of chlorhesidine diacetate and (ethoxy)5 octyl phenol (Triton X45) towards Bacillus megaterium KM-.

Chlorhexidine (0.5-0.65 microM) and Triton X45 (30-40 microM) added to exponential phase Bacillus megaterium KM- cultures was growth inhibitory. The presence of KCl (0.05-0.35 M) in the medium did not significantly affect growth rate in the absence of drug, yet reduced the growth inhibitory activity of the chlorhexidine and enhanced that of Triton X45. These effects were maximal at KCl concentrations of 0.2 M and above, when complete protection towards chlorhexidine and lysis of the cultures in the presence of Triton X45 were observed. Time-survivor curves in the presence of chlorhexidine (0.7-1.0 microM) gave LT90 values of 1.5-2.0 h in the absence of KCl, yet its inclusion (0.35 M) totally inhibited this low level bactericidal activity. Drug absorption by whole cell and isolated cell wall preparations was determined in the presence and absence of KCl (0.35 M). Chlorhexidine uptake by intact cells was reduced by approximately 50% in the presence of salt whereas that of Triton X45 increased by a similar fraction. Uptake of chlorhexidine by the cell wall fraction accounted for approximately 50% of that for the whole cells and was relatively unaffected by the presence of KCl. Conversely, absorption of Triton X45 by the cell wall fraction accounted for most of the uptake by whole cells and increased markedly in the presence of salts.

Bacillus megaterium↗

PubMed1998

Analysis of c-Fos and glial fibrillary acidic protein (GFAP) expression following topical application of potassium chloride (KCl) to the brain surface.

Application of high K+ concentrations to a limited area of the brain surface is known to trigger spreading depression. We used this model to observe the response of cortical areas, distant to the exposed site, at the cellular level. Immunostaining of glial fibrillary acidic protein (GFAP) and of the proto-oncogene c-Fos was analyzed in brain sections at different times after K+ application. Piriform and parietal cortices, as observed in coronal sections located 3 mm rostrally from the center of the stimulated area and ipsilateral to it, showed a dramatic increase in immunostaining for both markers. However, the time course for such increments was different. c-Fos protein(s) expression was high at 1.5 h and decreased at 24 h after K+ exposure and c-fos mRNA expression correlated with the immunohistochemical results. At these initial times GFAP immunoreactivity was still low but began to rise between 2 and 7 days after treatment in exactly the same areas where c-Fos expression had been up-regulated. No significant effect, for either marker, was evident in the contralateral piriform or parietal cortices. In addition, we studied the effects of the NMDA antagonist MK-801 (4 mg/kg i.p.) on the expression of mRNA for GFAP and c-fos and demonstrated a marked reduction in the upregulation of these genes.

Administration, Topical↗