Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rodent muscles were exposed to several organic calcium antagonists, and mechanical responses to direct electrical stimulation were recorded. Verapamil and D600, at 25 microM, depressed twitch and tetanus tension and caused fading of the tetanus plateau. These effects increased with frequency of stimulation, and were not reversed by doubled extracellular calcium. Depression of tension progressed to complete paralysis after 60-90 min exposure to verapamil. Bepridil and diltiazem both caused depression of tension and tetanus fade. Nifedipine caused marked, and nitrendipine caused slight, potentiation of twitch tension but did not alter tetanic tension. The magnitude of the observed effects on tension (either depression or potentiation) correlated with neither the relative calcium antagonist potencies of the drugs in other tissues nor with the ability of the drugs to cross the cell membrane. The continued decline in tension observed on prolonged exposure indicates that chronic exposure to low levels in vivo might lead to significant muscle weakness.
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PMID:Effects of calcium antagonists on mechanical responses of mammalian skeletal muscles. 241 76

We tested the hypothesis that accumulation of H+ or inorganic phosphate (Pi) is responsible for the early contractile failure of hypoxia by measuring maximal Ca2+-activated pressure and 31P nuclear magnetic resonance spectra in Langendorff-perfused ferret hearts at 30 degrees C. Maximal Ca2+-activated pressure was identified by the saturation of pressure with respect to [Ca2+]o observed during tetani as [Ca2+]o was increased to 15 mM in HEPES-buffered, 100% O2-bubbled perfusate and during hypoxia induced by bubbling with room air or with 100% N2. Tetani were produced by pacing at 8-12 Hz following exposure to ryanodine (1-5 microM), an inhibitor of Ca2+ release from the sarcoplasmic reticulum, and were elicited once a minute to measure maximal Ca2+-activated pressure during acquisition of nuclear magnetic resonance spectra. An inverse correlation was observed between [Pi] and maximal Ca2+-activated pressure (r = -0.87 mean, n = 12), with an average decline of 8.6% in pressure per 1 mumol/g wet wt. increase in [Pi]. Intracellular pH (pHi) showed no significant correlation with maximal Ca2+-activated pressure (r = 0.49 mean, n = 12). Two other protocols, pacing at variable rates and gated measurements at two different times during the tetanus, were also used to correlate [Pi], pHi, and maximal Ca2+-activated pressure. These protocols confirmed the highly significant correlation between [Pi] and maximal Ca2+-activated pressure, as well as the lack of correlation with pHi. Acidosis induced by NH4Cl (20 mM) or by bubbling with 95% O2/5% CO2 was associated with less than 20% depression of maximal Ca2+-activated pressure in the pHi range down to 6.8, but much greater depression at lower pHi. The data are consistent with depression of maximal Ca2+-activated force during the early phase of hypoxia by Pi but not by H+.
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PMID:Mechanism of early contractile failure during hypoxia in intact ferret heart: evidence for modulation of maximal Ca2+-activated force by inorganic phosphate. 242 80

Antibody responses against pneumococcal capsular antigens and tetanus toxoid were measured in 14 patients with chronic renal failure who were managed by continuous ambulatory peritoneal dialysis (CAPD) or haemodialysis (HD) and in eight healthy controls. IgG antipneumococcal responses were predominantly of the IgG2 and to a lesser extent IgG1 subclasses, while the IgG response against tetanus toxoid was largely IgG1 with smaller amounts of IgG4 and IgG3. The post-immunisation serum levels of IgG1 and IgM antibody against both antigens were significantly reduced in the uraemic patients compared with controls (P less than 0.05). All the uraemic patients had normal levels of IgG, IgA and IgM in the serum, but elevated levels of IgG3 prior to immunisation. The mechanisms responsible for the asymmetric depression of antibody responses in uraemia are unclear and may account in part for the increased susceptibility to infection in these patients.
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PMID:T-cell-independent and T-cell-dependent antibody responses in patients with chronic renal failure. 249 80

Eight cases of snakebite occurred in seven of 11 captive Rocky Mountain elk (Cervus elaphus nelsoni) during June and July 1987. Severity of reactions to envenomation varied; affected elk presented with combinations of signs that included painful swelling restricted to the face and muzzle, submandibular edema, inspiratory dyspnea, epistaxis, frothy, blood-tinged nasal discharge, epiphora, anorexia and anxiousness or depression. We observed puncture wounds in only two cases. Treatment consisted of dexamethasone (about 0.1 mg/kg subcutaneously, single dose) and procaine penicillin G (about 25,000 IU/kg subcutaneously, once or twice daily, for 5 to 6 days), as well as revaccination using clostridium and tetanus toxoids. Swelling resolved and elk recovered in 3 to 5 days without complications. Using immunodiffusion, we detected serum antibodies to prairie rattlesnake (Crotalus viridis viridis) venom in six of seven affected elk, demonstrating seroconversion in three cases and anamnesis in one elk bitten twice. Venom was undetectable in any serum samples using similar techniques.
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PMID:Snakebite in captive Rocky Mountain elk (Cervus elaphus nelsoni). 250 25

1. Single muscle fibres were dissected from Xenopus lumbrical muscles and microinjected with the photoprotein aequorin in order to measure the myoplasmic free calcium concentration ([Ca2+]i). Fatigue was produced by repeated intermittent tetanic stimulation continued until tension had declined to approximately 50% of the initial level. Fibres were then allowed to recover by giving tetani at less frequent intervals. Aequorin light (a measure of [Ca2+]i) and tension were measured during fatiguing stimulation and recovery. 2. During fatiguing stimulation, tetanic tension declined steadily, but peak aequorin light first increased before declining substantially. The largest light signal was about 155% of initial control while at the end of fatiguing stimulation the tetanic light fell to about 14% of control. 3. Fibres showed a characteristic slowing of relaxation in the fatigued state. This was associated with a slowing of the rate of decline of the aequorin light signal. 4. Intracellular acidosis produced by equilibrating the Ringer solution with either 5 or 15% CO2 caused an increase in the light signal associated with a tetanus. Carbon dioxide also caused a reduction of tension and a slowing of relaxation. 5. In vivo pCa-tension curves were constructed by exposing the fibres to a series of K+ concentrations which produced contractures of different sizes. Light and tension were measured during periods when both were relatively stable and the light signal was subsequently converted to pCa. 6. Exposure of fibres to 5 or 15% CO2 caused the pCa-tension curve to be shifted to the right of the control curve. This indicates a reduced Ca2+ sensitivity of the contractile proteins, which is in agreement with results from skinned fibre studies. 7. The pCa-tension points obtained from tetani during the early part of fatiguing stimulation also deviated to the right of the control pCa-tension curve, suggesting a reduced Ca2+ sensitivity of the contractile proteins. At the end of fatiguing stimulation, however, pCa-tension points did not differ greatly from the control pCa-tension curve, suggesting that Ca2+ sensitivity was approximately normal. Thus the reduced [Ca2+]i during tetani at the end of fatiguing stimulation (when tension was reduced to approximately 50%) could explain all of the reduction in tension. 8. After fatiguing stimulation, tension and light recovered monotonically in some fibres; however, in the majority of fibres, tension and light showed a secondary decline followed by a slower recovery (post-contractile depression). 9. During post-contractile depression, caffeine contractures or tetani in the presence of caffeine gave increased aequorin light signals and the tension developed was close to that produced in an unfatigued tetanus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Intracellular calcium and tension during fatigue in isolated single muscle fibres from Xenopus laevis. 251 88

Long-term potentiation (LTP), intensively studied in the hippocampus as a possible mnemonic device, has begun to be studied in the neocortex. In this study the effects of varying tetanic stimulus parameters on LTP of field potentials recorded from layer II/III induced by white matter stimulation in the in vitro rat visual cortical slice were examined. Low intensity tetanus was more effective in producing LTP than high-intensity tetanus, although single pulses of very high intensity reliably resulted in LTP. LTP consistently occurred following 2 Hz-60 min, or 100 Hz-10 min tetanus; whereas, 10 min of 7 and 25 Hz tetanus usually resulted in long-lasting depression. Although no obvious rule related tetanus frequency and duration to the incidence of LTP, an inverted-U relationship was found between tetanus frequency and LTP magnitude.
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PMID:Induction of LTP in rat primary visual cortex: tetanus parameters. 272 Mar 77

The effect of atracurium, a relatively new muscle relaxant, on neuromuscular transmission, in the rat diaphragm preparation, was studied, by analysing the characteristic features of tetanic fade and recovery pattern following a blocking concentration of atracurium (10 microns). Tetanic fade (TF) and peak tetanic tension (Tp) and its depression by atracurium, were analysed and the results were interpreted in terms of atracurium action at the neuromuscular junction. Atracurium reduced the sustained tetanic tension, elicited at 50 Hz for 0.5 s duration, and produced a marked tetanic fade in 38 s. Atracurium also reduced the peak tetanic tension by 40%, of the control value, in 38 s. Maximum tetanic tension was 5.7 g tension, and the time taken to completely block the tetanus was 4.75 +/- 0.15 min (means +/- SE, n = 8). Recovery from atracurium-induced blockade occurred in 30s (tetanic fade) and in 3-4 min (peak tetanic tension). It was concluded that atracurium produces a profound tetanic fade, at a time when the peak tetanic tension is reduced by only 40%. The data presented indicate that atracurium has a rapid onset of blockade, intermediate duration and a quick recovery profile at the rat neuromuscular junction.
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PMID:Assessment of neuromuscular blockade produced by atracurium in the rat diaphragm preparation. Measurements of tetanic fade, depression and recovery profile. 274 9

The influence of temperature (range 15-37 degrees C) on the isometric contractions of the slow twitch soleus (SOL) and the fast twitch extensor digitorum longus (EDL) muscles of mice, rats and guinea pigs were investigated in vitro. Cooling of the bathing solution prolonged the time parameters of single twitches and tetanic contractions in a non-linear manner in both muscle types of all animals. In muscles containing predominately fast twitch fibres like the EDL of all animals cooling was followed by an increase of the single twitch tension (cold potentiation) with a maximum of 160-180% at about 20 degrees C. The influence of a decrease of the temperature on the twitch tension was different in the SOL of the three animals. In SOL of mice (containing about 50% slow twitch fibres) the twitch tension was virtually unchanged, in SOL of rats (about 70% slow twitch fibres) a moderate cold depression and in SOL of guinea pigs (composed by slow twitch fibres only) a strong cold depression was observed. The maximum tetanic tension decreased progressively on cooling in all muscles and independently of their fibre type composition. Cooling increased the twitch-tetanus-ratio in fast twitch and decreased it in pure slow twitch muscles. It is concluded that the temperature dependence of the single twitch and the twitch-tetanus-ratio can be used as a physiological measure of the fibre type composition of a given muscle.
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PMID:Temperature effects on isometric contractions of slow and fast twitch muscles of various rodents--dependence on fibre type composition: a comparative study. 275 27

Long-lasting potentiation of transmitter release induced by repetitive presynaptic activities in bull-frog sympathetic ganglia was studied by recording intracellularly fast excitatory post-synaptic potentials (fast e.p.s.p.s.). Following a brief period of post-tetanic potentiation or depression (less than 10 min), the amplitude of the fast e.p.s.p. was potentiated for a period between several tens of minutes and more than 2 h in response to tetanic stimulation of the preganglionic nerve in twenty-one out of twenty-eight cells. Quantal analysis revealed that this long-term potentiation of the fast e.p.s.p. (l.t.p.) was accompanied by an increase in quantal content m (in nine out of twenty-one cells), quantal size (four cells) or both (eight cells). The increased quantal content (presynaptic l.t.p.) declined exponentially (ten cells) or decayed gradually to a certain enhanced level which lasted several hours. In contrast, the increased quantal size grew with a relatively long latency (10-25 min) and remained relatively constant for at least 2 h. The magnitude of presynaptic l.t.p. increased with increased duration of the presynaptic tetanus (33 Hz) from 2 to 5 s. No l.t.p. was elicited by a 1-s tetanus, whereas the time course appears to be independent of the tetanus duration and the magnitude of l.t.p. There was a positive correlation between the magnitude of presynaptic l.t.p. and the pre-tetanic quantal content up to m = 3, but the former deviated from linear regression when the value of the latter exceeded 3. No l.t.p. occurred when quantal content was less than 0.5. A tetanus (33 Hz, 10 s) applied in Ca2+-free solution elicited no presynaptic l.t.p., while the same tetanus in normal Ringer solution produced a large presynaptic l.t.p. Presynaptic l.t.p. was enhanced in magnitude at low temperature (8-10 degrees C). These results demonstrate the existence of a use-dependent, long-term potentiation of transmitter release in bull-frog sympathetic ganglia. Several possible mechanisms are discussed in terms of Ca2+-buffering mechanisms of the presynaptic nerve terminals.
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PMID:Long-term potentiation of transmitter release induced by repetitive presynaptic activities in bull-frog sympathetic ganglia. 286 Feb 40

Tetanus-induced (400 Hz, 200 pulses) long-lasting potentiation of the stratum radiatum-evoked CA1 population spike in hippocampal slices is not accompanied by any change in Na+-independent [3H]glutamate binding sites. Homosynaptic depression that occurs subsequent to either a low frequency tetanus (20 Hz, 600 pulses) or a transient exposure to Cl(-)-free (containing NO3-) medium is associated with an elevation in the amino acid binding. [3H]Glutamate uptake into slices was decreased following a high frequency (400 Hz, 200 pulses) tetanus but in the majority of cases was increased following a low frequency (20 Hz, 600 pulses) tetanus to stratum radiatum. When the high frequency tetanus was given in the absence of extracellular Ca2+, there was a further reduction in [3H]glutamate uptake.
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PMID:Tetanic stimulation-induced changes in [3H]glutamate binding and uptake in rat hippocampus. 287 13


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