Protein kinase C modulates field-evoked transmitter release from cultured rat cerebellar granule cells via a dendrotoxin-sensitive K+ channel

The role of protein kinase C (PKC) in the control of neurotransmitter release from cultured rat cerebellar granule cells was investigated. Release of preloaded [³H]-d -aspartate which is incorporated into synaptic vesicles in this preparation was evoked by electrical field stimulation or elevated KCl. PKC activation by phorbol esters resulted in a large facilitation of field-evoked Ca²⁺-dependent [³H]-d -aspartate release and a lesser enhancement of KCl-stimulated release. Inhibition of PKC by Ro 31-8220 or staurosporine virtually abolished field-evoked release but had no effect on KCl-evoked release. Field-evoked, but not KCl-evoked, synaptic vesicle exocytosis monitored by the fluorescent vesicle probe FM2-10 was inhibited by staurosporine. PKC was not directly modulating neurite Ca²⁺ channels coupled to release, as Ro 31-8220 did not inhibit these channels. Activation or inhibition of PKC modulated field-evoked plasma membrane depolarization, but had no effect on KCl-evoked depolarization, consistent with a regulation of Na⁺ or K⁺ channels activated by field stimulation. No modulation of field-evoked neurite Na⁺ influx was seen using phorbol esters. Phorbol ester-induced facilitation of field-evoked [³H]-d -aspartate release and neurite Ca²⁺ entry was non-additive with that produced by the specific K⁺ channel antagonist dendrotoxin-1, suggesting that PKC modulates transmitter release from field-stimulated cerebellar granule cells by inhibiting a dendrotoxin-1-sensitive K⁺ channel.     

Reduction of voltage-dependent currents by ethanol contributes to inhibition of NMDA receptor-mediated excitatory synaptic transmission

Previous studies have shown inhibitory effects of EtOH on NMDA receptor-mediated synaptic transmission in several brain regions. We examined this effect of EtOH under both current clamp and voltage clamp conditions in the basolateral amygdala because of the putative role of the amygdala in mediating anxiolytic effects of EtOH. We found that EtOH reduced NMDA receptor-mediated synaptic responses. In addition, we found that NMDA receptor-mediated depolarizations could also activate a voltage-dependent regenerative potential which was also sensitive to EtOH. Pharmacological characterization of this current was consistent with a high-threshold Ca²⁺ current. This current also exhibited a pronounced tendency towards transient enhancement upon withdrawal of EtOH.     

新加五痹汤治疗神经根型颈椎病的临床观察

目的 探讨新加五痹汤治疗神经根型颈椎病的临床疗效.方法 选取2019年1—12月来我院就诊的符合入选标准的神经根型颈椎病患者70例为研究对象,按随机数字表分为观察组和对照组.观察组35例使用新加五痹汤治疗,对照组35例采用颈痛颗粒联合甲钴胺分散片治疗.治疗周期均为4周.比较两组治疗前后VAS评分、NDI指数、临床疗效及...     

Proton modulation of M-like potassium current (IKx) in rod photoreceptors

The effect of extracellular pH (pH_e 6.9–8.1) and intracellular pH (pH_i 6.4–8.1) on the non-inactivating voltage-sensitive M-like potassium current (I_Kx) was studied in patch-clamped salamander rod photoreceptors. The midpoint of the I_Kx activation curve shifted by 6.6 mV per pH_e unit, with acidification producing positive shifts and alkalinization producing negative shifts. The time constant of I_Kx activation shifted with pH_e in a manner consistent with the shifts in the activation curve. Maximum conductance and gating charge were unaffected by changes in pH_e. I_Kx did not depend on pH_i. Given the importance of I_Kx in rod function, these results suggest that pH_e could affect the signal transmitted from rods by changing I_Kx activation parameters.     

Sleep EEG in mice that are deficient in the potassium channel subunit K.v.3.2

Voltage-gated potassium channels containing the K.v.3.2 subunit are expressed in specific neuronal populations such as thalamocortical neurons and fast spiking GABAergic interneurons of the neocortex and hippocampus. These K(+)-channels play a major role in the regulation of firing properties in these neurons. We investigated whether the K.v.3.2 subunit contributes to the generation of the sleep electroencephalogram (EEG). The EEG of a frontal and occipital derivation of K.v.3.2-deficient mice and littermate controls was recorded during a 24-h baseline, 6-h sleep deprivation (SD) and subsequent 18-h recovery to assess also the effects of the K.v.3.2 subunit deficiency under physiological sleep pressure. The K.v.3.2-deficient mice had lower EEG power density in the frequencies between 3.25 and 6 Hz in nonREM (NREM) sleep and 3.25-5 Hz in REM sleep. These differences were more prominent in the frontal derivation than in the occipital derivation. The waking EEG spectrum was not affected by the deletion. In both genotypes SD induced a prominent increase in slow-wave activity in NREM sleep (mean EEG power density between 0.75 and 4.0 Hz), and a concomitant decrease in sleep fragmentation. The effects of SD did not differ significantly between the genotypes. The results indicate that K.v.3.2 channels may be involved in the generation of EEG oscillations in the high delta and low theta range in sleep. They support the notion that GABA-mediated synchronization of cortical activity contributes to the electroencephalogram.     

Amlodipine reduces cyclosporin-induced hyperuricaemia in hypertensive renal transplant recipients.

BACKGROUND: Hypertension and hyperuricaemia are common side-effects of cyclosporin A (CsA) treatment in renal transplant recipients. While it is well established that the calcium channel blocker amlodipine can control CsA-induced hypertension effectively in this patient population, recent evidence suggests amlodipine might also reduce hyperuricaemia. The present study was designed to compare the effects of the calcium channel blocker amlodipine (5-10 mg/day) and the beta-adrenoceptor antagonist tertatolol (5-10 mg/day) on CsA-induced hyperuricaemia in post-renal transplant recipients with hypertension. METHODS: Forty-eight hypertensive renal transplant recipients on a stable dose of CsA were randomized in a double-blind, parallel-group manner to receive either amlodipine (n = 24) or tertatolol (n = 24) for 60 days. The primary outcome measure was the change from baseline in serum uric acid concentration. Secondary analyses of efficacy were based on changes in renal function and blood pressure. RESULTS: Amlodipine significantly decreased serum uric acid levels from 483 +/- 99 to 431 +/- 110 microM/l (P < 0.001), while tertatolol significantly increased uric acid from 450 +/- 98 to 476 +/-84 microM/l (P = 0.006). Amlodipine also significantly increased glomerular filtration rate (P = 0.0048) and the clearance rate of uric acid (P = 0.023) and it reduced the fractional proximal tubular reabsorption of sodium (P < 0.001), compared with tertatolol. Renal plasma flow and filtered fraction were unaffected by both treatments, as was trough CsA blood concentration. Amlodipine lowered systolic blood pressure to a significantly greater extent than did tertatolol (P = 0.007). The time-dependent profile of diastolic blood pressure did not differ significantly between treatment groups. Both drugs were well tolerated. CONCLUSIONS: Amlodipine could be more appropriate than tertatolol for CsA-induced hypertension and hyperuricaemia in renal transplant recipients.     

Hyperinsulinemic hypoglycemia evolving to gestational diabetes and diabetes mellitus in a family carrying the inactivating ABCC8 E1506K mutation

Vieira TC, Bergamin CS, Gurgel LC, Moisés RS. Hyperinsulinemic hypoglycemia evolving to gestational diabetes and diabetes mellitus in a family carrying the inactivating ABCC8 E1506K mutation. Congenital hyperinsulinism of infancy (CHI) is the most common cause of hypoglycemia in newborns and infants. Several molecular mechanisms are involved in the development of CHI, but the most common genetic defects are inactivating mutations of the ABCC8 or KCNJ11 genes. The classical treatment for CHI has been pancreatectomy that eventually leads to diabetes. More recently, conservative treatment has been attempted in some cases, with encouraging results. Whether or not the patients with heterozygous ABCC8 mutations submitted to conservative treatment may spontaneously develop type 2 diabetes in the long run, is a controversial issue. Here, we report a family carrying the dominant heterozygous germ line E1506K mutation in ABCC8 associated with persistent hypoglycemia in the newborn period and diabetes in adulthood. The mutation occurred as a de novo germ line mutation in the mother of the index patient. Her hypoglycemic symptoms as a child occurred after the fourth year of life and were very mild, but she developed glucose metabolism impairment in adulthood. On the other hand, in her daughter, the clinical manifestations of the disease occurred in the neonatal period and were more severe, leading to episodes of tonic–clonic seizures that were well controlled with octreotide or diazoxide. Our data corroborate the hypothesis that the dominant E1506K ABCC8 mutation, responsible for CHI, predisposes to the development of glucose intolerance and diabetes later in life.