Diazepam increases calcium sensitivity of the skinned cardiac muscle fiber in guinea pig

Influences of diazepam, a benzodiazepine derivative, on the contractile response to calcium in skinned trabecular fibers of guinea pig heart were examined. Diazepam (100 microM) enhanced the contractile response of the skinned fiber to calcium and shifted the concentration-response curve to the left. The pCa50 values were 6.07+/-0.03 and 6.28+/-0.03 (P<0.05) in the absence and presence of diazepam, respectively. This result suggests that diazepam increases calcium sensitivity of contractile proteins in heart muscles.     

Reversing hypoxic cell chemoresistance in vitro using genetic and small molecule approaches targeting hypoxia inducible factor-1

The resistance of hypoxic cells to conventional chemotherapy is well documented. Using both adenovirus-mediated gene delivery and small molecules targeting hypoxia-inducible factor-1 (HIF-1), we evaluated the impact of HIF-1 inhibition on the sensitivity of hypoxic tumor cells to etoposide. The genetic therapy exploited a truncated HIF-1alpha protein that acts as a dominant-negative HIF-1alpha (HIF-1alpha-no-TAD). Its functionality was validated in six human tumor cell lines using HIF-1 reporter assays. An EGFP-fused protein demonstrated that the dominant-negative HIF-1alpha was nucleus-localized and constitutively expressed irrespective of oxygen tension. The small molecules studied were quinocarmycin monocitrate (KW2152), its analog 7-cyanoquinocarcinol (DX-52-1), and topotecan. DX-52-1 and topotecan have been previously established as HIF-1 inhibitors. HT1080 and HCT116 cells were treated with either AdHIF-1alpha-no-TAD or nontoxic concentrations (0.1 microM; 相似文献   

长期应用地西泮对豚鼠耳蜗微音器电位的影响

目的观察长期应用地西泮对豚鼠耳蜗微音器电位的影响。方法采用逐渐增加剂量的方法皮下注射地西泮3个月后停药,10d后用不同强度的短声刺激诱发微音器电位产生,测量诱发微音器电位产生的阈值,用共聚焦显微镜测量耳蜗毛细胞内Ca2+浓度的变化。结果应用地西泮3个月后停药,与对照组相比,引起豚鼠微音器电位产生的阈值明显降低,微音器电位的幅度显著增加,记录出自发的微音器电位,毛细胞内Ca2+浓度降低。结论长期应用地西泮后豚鼠耳蜗对声刺激的敏感性增加可能与毛细胞内Ca2+浓度降低有关。     

Diazepam-induced prospective memory impairment and its relation to retrospective memory, attention, and arousal

The amnestic effects of benzodiazepines are well documented on a variety of memory tasks. However, prospective memory (PM), or remembering to execute an action at a future time, has not been studied previously. This study examined the effect of diazepam on word list recall, PM, sustained attention, and subjective ratings of arousal. Forty-eight healthy participants, aged 19-35, received an average of 0.19 mg/kg oral diazepam or placebo in a double-blind manner. Retrospective memory and PM were assessed by free recall of unrelated word lists and by instructing participants to request a hidden belonging at the end of the session, respectively. Sustained attention was measured by multiple trials of a digit cancellation task, and subjective arousal was assessed by self-ratings of drowsiness. Diazepam impaired performance on all measures, including PM. Reduced PM performance was associated with decreased subjective arousal in the diazepam group but was unrelated to sustained attention. This is the first report of the effects of benzodiazepines on prospective remembering, and further supports the view that the arousal/attentional system is composed of partially independent subsystems that have differential relationships to memory.     

Effect of a polyethylene-lined administration set on the availability of diazepam injection

Delivery of diazepam through a polyethylene-lined i.v. administration set and through a polyvinyl chloride (PVC) set was compared. Diazepam was prepared in concentrations of 50 mg/500 mL and 100 mg/500 mL in 0.9% sodium chloride injection and 5% dextrose injection in glass containers. Diazepam concentrations were measured by high-performance liquid chromatography at 0 through 5 hours in samples collected simultaneously from the glass solution containers and from the distal ends of a PVC administration set and a polyethylene-lined (non-PVC) set. Flow rates of 50 and 100 mL/hr were tested. For the non-PVC sets, diazepam concentration in the infusate was not significantly different from concentration in the glass container at any sampling time. The overall percentage of diazepam recovered was 100.7 +/- 6.8%. For the PVC sets, diazepam concentration in the infusate was less than in the container at all sampling times, and the overall percentage of diazepam recovered was 65.4 +/- 13.3% (significantly different from delivery for the non-PVC sets). Delivery through the non-PVC sets was not affected by flow rate, type of solution, or concentration of diazepam. For infusion periods of up to five hours, delivery of diazepam through polyethylene-lined i.v. administration sets was superior to delivery through polyvinyl chloride sets.     

Electroencephalographic study with SC-48274, a novel nonbenzodiazepine anxiolytic in conscious rabbits]

The electroencephalographic (EEG) effects of SC-48274 were investigated in conscious rabbits and compared with those of buspirone and diazepam. SC-48274 (20-30 mg/kg, i.v.) evoked an increase in drowsy EEG pattern period. Diazepam (2-3 mg/kg, i.v.) also increased the drowsy EEG pattern, while buspirone (0.5 mg/kg, i.v.) increased the arousal EEG pattern period. Neither SC-48274 nor buspirone affected the EEG arousal response to both auditory stimulation and electrical stimulation of the midbrain reticular formation of the posterior hypothalamus, while diazepam markedly suppressed the responses to both stimulations. The recruiting response to centromedian thalamic stimulation was not significantly affected by SC-48274 and buspirone, and it was slightly enhanced by diazepam. Neither SC-48274 nor buspirone had any effect on the photic driving response to flash light in the occipital cortex, while the response was markedly suppressed by diazepam. The duration of afterdischarges induced by electrical stimulation of the dorsal hippocampus was slightly inhibited by SC-48274 and markedly inhibited by diazepam, while buspirone enhanced the duration. These results suggest that the EEG effect of SC-48274 is quite different to those of buspirone and diazepam with respect to the qualitative aspects. We also suggest that SC-48274, unlike diazepam, is an effective anxiolytic drug with weak sedation.     

Electrophysiological and behavioral effects of 1-methyl-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-540) in cats and rabbits.

Effects of ID-540 (1-methyl-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one) on the central nervous system were evaluated electrophysiologically and behaviorally in cats and rabbits. The reference compound used was diazepam. 1. ID-540 as well as diazepam produced muscle relaxation, grooming, facilitation of appetite and suppression of defensive behaviors. ID-540 made the animals lie on their side during sleep, but diazepam did not. 2. Though more effectively inducing an increase in fast activity and a decrease in frequency of hippocampal theta-waves than diazepam, ID-540 scarcely affected the amplitude of subcortical EEG (hippocampus, amygdala and hypothalamus), which diazepam decreased in cats. 3. ID-540 and diazepam increased the waking phase and decreased the paradoxical sleep phase. 4. ID-540 and diazepam at a dose of 1 mg/kg decreased the duration of amygdala after-discharge for 1 h in cats. Diazepam increased the duration of the after-discharge after it had been decreased, but ID-540 did not. ID-540 did not affect the duration of hippocampal after-discharge whereas diazepam prolonged it. 5. ID-540 depressed more effectively the hippocampal arousal response to stimulation of the ventro-medial hypothalamus than did diazepam in rabbits. 6. ID-540 depressed amygdalo-hippocampal evoked potential in cats. 7. ID-540 did not affect norepinephrine-induced pressor response but reduced hypothalamic pressor response in cats.     

Absolute bioavailability and effect of food and antacid on diazepam absorption from a slow-release preparation

A series of healthy volunteers received a single 7.5-mg intravenous dose of diazepam on one occasion and a single 15-mg oral dose of slow-release diazepam (DZ-SR) on another occasion. Diazepam concentrations were measured by gas chromatography in multiple plasma samples drawn during seven days after each dose. Absorption of diazepam from DZ-SR was slow, with mean +/- S.E. peak concentrations attained at 3.8 +/- 0.5 hours after dosage. Absolute bioavailability of DZ-SR averaged 0.98 +/- 0.06. In two other studies, diazepam absorption from DZ-SR was evaluated when coadministered with a standard breakfast or with an antacid preparation (Maalox). Neither food nor antacid altered the rate of diazepam absorption and did not impair the completeness of absorption. Higher peak total plasma diazepam concentrations occurred in the postprandial as opposed to the fasting state, but this was an artifact of reduced protein binding (increased free fraction) due to fasting. Thus, diazepam absorption from DZ-SR is slow and essentially complete.     

Benzodiazepines inhibit neutrophil chemotaxis and superoxide production in a stimulus dependent manner; PK-11195 antagonizes these effects.

Diazepam, which binds both central (neuronal) and peripheral (non-neuronal) benzodiazepine binding sites, and Ro5-4864, a ligand selective for benzodiazepine peripheral binding sites (PBS), both inhibited the FMLP induced chemotaxis in human neutrophils at concentrations as low as 10(-8) M. A selective peripheral benzodiazepine antagonist, PK-11195 (10(-5) M), partially reversed the benzodiazepine inhibition of chemotaxis. Diazepam also inhibited the superoxide production induced by FMLP, NaF, and A23187, but not that induced by PMA whose stimulant action was insensitive even to 10(-4) M diazepam. The FMLP-induced superoxide production was most sensitive to diazepam inhibition (ID50 = 2.25 x 10(-6) M diazepam); the effect of NaF was slightly less sensitive (ID50 = 1.34 x 10(-5) M diazepam); and the effect of A23187 was least sensitive as it was suppressed only at 10(-4) M diazepam concentrations. Like diazepam, Ro5-4864 inhibited the FMLP-induced superoxide production, and PK-11195 (10(-5) M) significantly antagonized both diazepam and Ro5-4864 inhibition. Binding studies showed the presence of a saturable benzodiazepine 'peripheral' type binding site (PBS) on human neutrophils with a Kd of 1.2 +/- 0.06 x 10(-8) M (+/- SEM), and a Bmax of 1028 +/- 86.2 fmol/10(6) cells (+/- SEM) for [3H]Ro5-4864; the binding was displaceable by PK-11195, Ro5-4864 and diazepam but not by clonazepam.     

Antipunishment effects of diazepam: Interaction with shock and food deprivation levels in pigs

The effects of 1 mg/kg diazepam on punished behaviour of pigs were inyestigated under various degrees, of food deprivation and/or shock level. Responses emitted during the punishment signal were affected more by the shock level than by the degree of food deprivation while nonpunished responses rates were modified by neither factor. Diazepam treatment increased the number of responses emitted during the punishment signal but interacted with the shock intensity: drug effects were attenuated when the shock intensity was severe, in spite of an equivalent control baseline. Diazepam also increased the overall rate of nonpunished responding. The drug treatment had no reliable effect on flinch and escape thresholds measured in separate experiments. The effects of diazepam on punished responding do not appear to be related to eventual changes in food motivation or sensitivity to electric shock     

Effect of BTS 49465 on hypoxic pulmonary vasoconstriction

The effect of BTS 49465 on hypoxic pulmonary vasoconstriction was compared with placebo and sodium nitroprusside in 10 spontaneously breathing anesthetized mongrel dogs. Vascular pressures, cardiac output, and arterial blood gases were monitored on 2 study days (greater than 1 week apart) during which, after baseline measurements on room air, the pulmonary pressor response to alveolar hypoxia (12% O2) and the effect of sodium nitroprusside (10 micrograms/kg/min) were assessed. The animals then inspired room air and, after the pressures had returned to baseline, either BTS 49465 (10 mg/kg, i.v.) or an equal volume of placebo was administered. The animals were monitored for the next 3.5 h. Although the room air and initial hypoxic (PaO2 = 50 +/- 1.5 torr) measurements were similar in both studies, 1 h after BTS 49465 was administered there was a significant reduction in pulmonary artery pressure (21.6 +/- 1.3 versus 27.6 +/- 1.8 torr, p less than 0.05), which was maintained throughout the 3.5 h study period. There was also a small increase in cardiac index from 4.1 +/- 0.4 to 4.6 +/- 0.2 L/min/m2 after BTS 49465 which was not statistically significant. Quantitatively the effects of BTS 49465 and sodium nitroprusside were similar. We conclude that BTS 49465 is an effective pulmonary vasodilator that ameliorates hypoxic vasoconstriction.     

Effects of diazepam on behaviour suppressed by extinction in pigs

Diazepam injected to pigs previously trained to perform an operant response for food according to a continuous reinforcement schedule significantly increased resistance to extinction compared to control pigs. In pigs submitted to a time-out procedure diazepam increased the number of nonreinforced responses at the beginning of the acquisition but was unable to disinhibit suppressed behaviour in the later stages of acquisition when the extinguished behaviour was well acquired. The results are discussed with respect to antiaversive or disinhibitory effects of bonzodiazepines and an alternative interpretation, the strengthening of the prevailing behavioural tendency in the animal's repertoire at the time of test, is put forward.     

The role of diazepam in the treatment of nerve agent poisoning in a civilian population

The main site of action of diazepam, as with other benzodiazepines, is at the GABA(A) receptor, although it has been suggested that some of the potentially beneficial actions of diazepam in nerve agent poisoning are mediated through other means. It is likely that convulsions may have long-term sequelae in the central nervous system, because of damage by anoxia and/or excitotoxicity. Numerous pharmacodynamic studies of the action of diazepam in animals experimentally poisoned with nerve agents have been undertaken. In nearly all of these, diazepam has been studied in combination with other antidotes, such as atropine and/or pyridinium oximes, sometimes in combination with pyridostigmine pretreatment. These studies show that diazepam is an efficacious anticonvulsant in nerve agent poisoning. There is considerable experimental evidence to support the hypothesis that diazepam (and other anticonvulsants) may prevent structural damage to the central nervous system as evidenced by neuropathological changes such as neuronal necrosis at autopsy. In instances of nerve agent poisoning during terrorist use in Japan, diazepam seems to have been an effective anticonvulsant. Consequently, the use of diazepam is an important part of the treatment regimen of nerve agent poisoning, the aim being to prevent convulsions or reduce their duration. Diazepam should be given to patients poisoned with nerve agents whenever convulsions or muscle fasciculation are present. In severe poisoning, diazepam administration should be considered even before these complications occur. Diazepam is also useful as an anxiolytic in those exposed to nerve agents.     

Influence of benzodiazepines on the response of the guinea-pig isolated trachea to the contractile action of adenosine.

The effects of diazepam and other agonists of central or peripheral benzodiazepine receptors were studied on the contractile action of adenosine, 2-chloroadenosine and R-PIA (N6-(L-2-phenylisopropyl)-adenosine) on the guinea-pig isolated trachea. These effects were compared to those of dipyridamole. Diazepam 10(-7) to 10(-5) M potentiated the efficacy of adenosine; the maximal contractile effect of adenosine (% vs. acetylcholine 10(-3) M) was 20.4 +/- 4.2 (n = 21) in control conditions and 45.5 +/- 3.7 (n = 6; P less than 0.001) in the presence of diazepam 10(-5) M. Ro5-4864 (10(-7) to 10(-5) M) or alpidem (10(-7) to 10(-5) M), both agonists of peripheral benzodiazepine receptors, potentiated the contractile effects of adenosine to the same extent as diazepam. Clonazepam and zopiclone, both agonists of central benzodiazepine receptors, did not modify these effects. Antagonists of central (flumazenil) or peripheral (RP 52028) benzodiazepine receptors had no influence on the interaction between diazepam or Ro5-4864 and adenosine. Conversely, dipyridamole significantly reduced (10(-7) M) or suppressed (10(-6) M) the contractile effects of adenosine. The contractile effects of 2-chloroadenosine and R-PIA were weakly affected in presence of high concentrations of diazepam and dipyridamole. Epithelium removal potentiated the contractile effect of adenosine on the guinea-pig isolated trachea and increased the potentiating effect of diazepam. It is concluded that benzodiazepines and related compounds can potentiate the contractile effect of adenosine on the guinea-pig isolated trachea through the activation of a peripheral receptor for the benzodiazepines and the resulting inhibition of adenosine uptake.     

Fear-dependent variations in continuous avoidance behavior of pigs

Previously acquired continuous avoidance performance of pigs in a shuttle-box was modified by a Pavlovian fear-conditioning procedure. Diazepam (1 mg/kg) given before the Pavlovian conditioning session prevented the increase in corticosteroids and the impairment of performance in the subsequent test session before the presentation of the fear signal. Diazepam given before the Pavlovian conditioning session and/or the test session did not prevent the increase of response to the CS presentation; however, the temporal pattern of increase differed according to the drug condition: the diazepam treatment on the day of the test significantly delayed the peak of responding to the CS; in pigs treated with diazepam on the day of Pavlovian conditioning and with saline on the day of test, the increase of response was diffuse instead of being localized to the CS presentation period. Pigs treated with diazepam both during learning and performance of fear conditioning showed some evidence of performance facilitation. Usual unitary interpretations cannot account for such results which would appear to be the net result of several intermingled effects among which state-dependent learning, acquisition deficit, and performance facilitation seem to be of importance.     

Different sensitivity of pain-related chemosensory potentials evoked by stimulation with CO2, tooth pulp event-related potentials, and acoustic event-related potentials to the tranquilizer diazepam.

1. The aim of this study was to investigate the sensitivity of pain-related potentials used in experimental pain models to the non-specific effects of the tranquilizer diazepam. Pain-related potentials were recorded after painful stimulation of the nasal mucosa with CO2 and after painful stimulation of the tooth pulp. Acoustically evoked potentials were measured in order to compare their sensitivity to the tranquilizer diazepam with the sensitivity of the pain-related potentials. 2. Twenty volunteers participated in this randomised, double-blind, three-fold crossover study. Measurements were obtained before and 20 min after the administration of the drug. Event-related potentials were recorded after painful stimulation of the nasal mucosa with CO2 (two stimulus intensities: 60% v/v and 70% v/v CO2), after painful stimulation of the tooth pulp (two stimulus intensities: 2.2 x and 3.3 x detection threshold), and after non-painful acoustical stimulation of the right ear. The subjects rated the perceived intensity of the painful stimuli by means of a visual analogue scale. In addition the spontaneous EEG was analysed in the frequency domain and the vigilance of the subjects was assessed in a tracking task. 3. Diazepam reduced significantly the amplitudes of the event-related potentials after painful stimulation of the tooth pulp and after acoustical stimulation. In contrast only a small, statistically non-significant reduction could be found after painful stimulation with CO2. The pain ratings of the painful stimuli were not affected by diazepam. Diazepam reduced the performance of the tracking task. A decrease of arousal could be found in the alpha 2-range, whereas in the beta 2 and the theta-range the power density increased under diazepam. 4. We demonstrated that event-related potentials after painful stimulation of the nasal mucosa with CO2 are less affected by the nonspecific effects of the tranquilizer diazepam than event-related potentials after painful stimulation of the tooth pulp. The effects of diazepam on the tracking task, the spontaneous EEG and the event-related potentials clearly confirm its sedative properties. Diazepam had no analgesic effect measurable by pain intensity estimates.     

Application of the axial dispersion model of hepatic drug elimination to the kinetics of diazepam in the isolated perfused rat liver.

The application of the axial dispersion model to diazepam hepatic elimination was evaluated using data obtained for several conditions using the single-pass isolated perfused rat liver preparation. The influence of alterations in the fraction unbound in perfusate (fu) and perfusate flow (Q) on the availability (F) of diazepam was studied under steady conditions (n = 4 in each case). Changes in fu were produced by altering the concentration of human serum albumin (HSA) in the perfusion medium while maintaining diazepam concentration at 1 mg L-1. In the absence of protein (fu = 1), diazepam availability was 0.011 +/- 0.005 (mean +/- SD). As fu decreased, availability progressively increased and at a HSA concentration of 2% (g/100 ml), when fu was 0.023, diazepam availability was 0.851 +/- 0.011. Application of the axial dispersion model to the relationship between fu and F provided estimates for the dispersion number (DN) of 0.337 +/- 0.197, and intrinsic clearance (CL(int)) of 132 +/- 34 ml min-1. The availability of diazepam during perfusion with protein-free media was also studied at three different flow rates (15, 22.5, and 30 ml min-1). Diazepam availability always progressively increased as perfusate flow increased, with the axial dispersion model yielding estimates for DN of 0.393 +/- 0.128 and CL(int) of 144 +/- 38 ml min-1. The transient form of the two-compartment dispersion model was also applied to the output concentration versus time profile of diazepam after bolus input of a radiolabeled tracer into the hepatic portal vein (n = 4), providing DN and CL(int) estimates of 0.251 +/- 0.093 and 135 +/- 59 ml min-1, respectively. Hence, all methods provided similar estimates for DN and CL(int). Furthermore, the magnitude of DN is similar to that determined for noneliminated substances such as erythrocytes, albumin, sucrose, and water. These findings suggest that the dispersion of diazepam in the perfused rat liver is determined primarily by the architecture of the hepatic microvasculature.     

Effects of single oral doses of clobazam,diazepam and lorazepam on performance tasks and memory

Summary The effects on memory and psychomotor performance and the subjective effects of three anxiolytic benzodiazepines (lorazepam 2 mg, diazepam 10 mg and clobazam 20 mg p.o.) have been evaluated in a double-blind, placebo-controlled, cross-over study in 10 healthy volunteers.At each session, measurements were made prior to and +3.5 h after drug administration, except in the case of REY's test, which was presented at H+1 h (learning) and was evaluated at H+8 h and at H+24 h (delayed recall).Single clinical doses of diazepam and lorazepam caused anterograde amnesia by disturbing acquisition, consolidation and retrieval. Clobazam did not impair memory.Lorazepam impaired performances in all the tests used to evaluate perception, immediate memory, reaction time, psychomotor skill and intellectual capacity. Diazepam caused a decrease in cortical arousal and the speed of perception of visual stimuli, whereas clobazam increased reaction time and reduced cortical arousal. Lorazepam caused a significant degradation of performance relative to the other two treatments.     

Clinical and physiological assessment of chlorazepate, diazepam and placebo in anxious neurotics.

A 28-day double-blind assessment of chlorazepate dipotassium, diazepam and placebo was done on 30 outpatient neurotics with a primary symptom of anxiety. Acute, sub-acute and more chronic effects of the drug were assessed after 3 hours, 14 days and 28 days of drug administration. A battery of psychiatric ratings as well as physiological and psychophysiological assessments were done at each period. The psychometric assessments showed a trend for diazepam to be the most anxiolytic of the three drugs, followed by chlorazepate and then placebo. These measurements did not reach uniform statistically significant differences. Psychological measurements demonstrated the same trends, but some of these reached statistically significant levels. These parameters also indicate a slightly different mode of action of the two drugs at equimolecular doses. Diazepam would depress baseline and stimulation arousal, whereas chlorazepate would decrease baseline CNS arousal, but facilitate CNS response upon stimulation.     

The nullification by diazepam of haloperidol-induced increases in the level of striatal dopamine but not in the activity of glutamic acid decarboxylase

In the therapeutic management of neuroleptic-induced tardive dyskinesia, diazepam, baclofen or gamma-vinyl-gamma-aminobutyric acid have been advocated. It has been postulated, but not proven, that the beneficial effects of these agents in tardive dyskinesia may be mediated by enhancing GABAergic transmission. In this study, it is reported that, during a 3-day withdrawal period following daily administration of 3 mg/kg of haloperidol (i.p.) for 3 weeks, the activity of glutamic acid decarboxylase in the striatum increased from 72.6 +/- 7.8 to 92.5 +/- 10.2 nmol 14CO2/mg protein/hr, and the concentration of dopamine in the striatum increased from 7.87 +/- 0.23 to 8.86 +/- 0.38 micrograms/g wet tissue. Diazepam (5 mg/kg, i.p.), given during the withdrawal period from haloperidol was able to nullify the enhancement in the concentration of dopamine but not in the activity of glutamic acid decarboxylase in the striatum. The results of these studies are interpreted to indicate that the reported beneficial effects of diazepam and GABA-mimetic agents in ameliorating the symptoms of tardive dyskinesia may occur through a mechanism which does not necessarily link transmission involving both dopamine and GABA.