Delayed anti-arrhythmic effect of nitroglycerin in anesthetized rats: involvement of CGRP, PKC and mK ATP channels

Delayed anti-infarct and anti-stunning effects of nitroglycerin (NTG) have well been established in some animal models. The main goals of this study in anesthetized rats were to determine whether NTG has a delayed anti-arrhythmic effect and if so, whether calcitonin gene-related peptide (CGRP), protein kinase C (PKC) and mitochondrial K(ATP) channels (mK(ATP)) are involved in triggering this response. For this purpose, on day 0, male Wistar rats received NTG (120 microg/kg, iv) with or without pre-administration of PKC inhibitor chelerythrine (CHE), capsaicin (CAP) to deplete CGRP from sensory nerves or mK(ATP) channel blocker 5-hydroxydecaonic acid (5HD). On day 1, their hearts were subjected to 30 min ischemia and 120 min reperfusion. In rats pretreated with NTG, the incidence of ventricular tachycardia and ventricular fibrillation and the mortality rate significantly reduced (from 100%, 61% and 18.1% in the control group to 45.4%, 10% and 0% in the NTG group, respectively). Infarct size also reduced from 58+/-4.7% in the control group to 31+/-3.7% in the NTG group. These effects were abolished by CHE, CAP and 5HD, which none of them alone had any effect on infarct size or the incidence of myocardial arrhythmias. These results show that a low dose of NTG has a delayed anti-arrhythmic effect and this effect may share a common mechanism with anti-infarct effects of this drug, involving CGRP release and PKC and mK(ATP) activation.     

Six hours of resting platelet concentrates stored at 22–24 oC for 48 hours in permeable bags preserved pH,swirling and lactate dehydrogenase better and caused less platelet activation

Background

During transportation, platelet concentrates (PC) usually undergo a long period without agitation. Whether this interruption improves quality and viability or, contrariwise, has deleterious effects on PC stored for 48 hours (h) is unknown. The aim of this study was to investigate the effects of metabolic resting (6 h of interruption of agitation) vs continue agitation of PC stored for 48 h in the blood bank of Tehran.

Materials and methods

PC were prepared from platelet-rich plasma and stored in permeable bags in a shaker/incubator for 42 h at room temperature (20–24 ºC). Then, simply by stopping the agitator, the PC remained stationary (“resting”) without agitation for 6 h (WCA6h), prior to transfusion. In vitro measurements of platelet quality were carried out just after completion of the resting period and the results were compared with those of PC continuously agitated in the same day (designated as the control group, CA6h). The in vitro variables measured were swirling, ristocetin-induced aggregation (GPIb-related function), lactate dehydrogenase (LDH) concentration, platelet factor 4 (PF4) release and P-selectin expression (activation markers).

Results

The mean platelet counts of the control group (CA6h) and rested (WCA6h) PC were not statistically different (P =0.548). Likewise, the mean pH values were not significantly different: WCA6h (7.16±0.08) and CA6h (7.22±0.16) (P =0.300). Although ristocetin-induced aggregation did not differ significantly between CA6h (79.2±4.4) and WCA6h (66.65±28.55) (P =0.186), WCA6h showed significantly less PFA release (P =0.015) and lower P-selectin expression (P =0.006).

Conclusions

We observed that PC stored under agitation for 42 h at 22–24 ºC in permeable bags and then rested for 6 h had better preserved pH, swirling and LDH and less platelet activation then PC kept under continuous agitation for the whole 48 h storage period.     

Scanning Electron Micrograph and Surface Hardness of Mineral Trioxide Aggregate in the Presence of Alkaline pH

IntroductionThe aim of this study was to evaluate morphologic microstructure and surface hardness of white mineral trioxide aggregate (WMTA) after exposure to a range of alkaline environments during hydration.MethodsWMTA was mixed and packed into 60 glass tubes. Four groups, each containing 15 tubes, were exposed to pH values of 7.4, 8.4, 9.4, and 10.4, respectively, for 3 days. In 12 tubes in each group, Vickers surface hardness was measured after exposure to alkaline environments. Data were subjected to one-way analysis of variance and a post hoc Tukey test. Three specimens in each group were prepared to be evaluated under a scanning electron microscope using scattered electron (SE) and backscattered electron (BSE) detectors.ResultsThe mean surface hardness values ± standard deviation after exposure to pH values of 7.4, 8.4, 9.4, and 10.4 were 58.28 ± 8.21, 68.84 ± 7.19, 67.32 ± 7.22, and 59.22 ± 9.14, respectively. The difference between these values was statistically significant (p = 0.000). There were statistically significant differences between pH values of 8.4 and 9.4 and pH values of 7.4 and 10.4 (p > 0.05). The SE detector revealed needle-shaped crystals at pH values of 7.4 and 8.4 and an amorphous microstructure at pH values of 9.4 and 10.4 on WMTA surface. The BSE detector showed more unhydrated structure and pores at pH values of 7.4 and 10.4 compared with pH values of 8.4 and 9.4.ConclusionsSurface hardness can be influenced by different alkaline pH values. The BSE detector can reveal more microstructure details of WMTA in conjunction with the SE detector. More porosity and unhydrated structure are observed in WMTA exposed to pH values of 7.4 and 10.4.     

Mirror movements and ipsilateral motor evoked potentials in ALS.

It can be difficult to detect upper motor neuron (UMN) involvement in early amyotrophic lateral sclerosis (ALS). The present study tested the usefulness of mirror movements (MMs), i.e., contralateral coactivation of hand muscles, as a UMN sign in ALS. Thirty-seven patients with possible, probable or definite ALS and 19 patients with suspected ALS without clinical signs of UMN involvement, 21 disease controls and 15 healthy volunteers were included. MMs were studied clinically, electromyographically and by transcranial magnetic stimulation (TMS), looking for ipsilateral motor evoked potentials (IMEPs). MMs were observed clinically in 15 ALS patients (27%) and electromyographically in 28 (50%). IMEPs in the abductor pollicis brevis muscle following TMS were recorded in 34 (61%) of all ALS patients and in nine (47%) out of 19 patients with suspected ALS, but not in healthy controls. Central motor conduction times were prolonged in 15 ALS patients (27%). It is concluded that MMs, especially if studied by EMG and TMS (IMEPs) can essentially improve detection of UMN involvement, especially in early stages of ALS.