Dynamic Restructuring of the Myocardial Mitochondria in Response to Uridine Modulation of the Activity of Mitochondrial ATP-Dependent Potassium Channel under Conditions of Acute Hypoxic Hypoxia.

We studied the effects of in vivo modulation of activity of mitochondrial ATP-dependent potassium channel (mitoKATP) by uridine on the morphofunctional state of mitochondria in rat cardiomyocytes under conditions of acute hypoxia. Preinjection of uridine to animals reduced the number of structurally modified mitochondria, but had practically no effect on their morphogenesis after hypoxia. Uridine in vivo stimulated the formation of micromitochondria and their release into the cytoplasm. The number of "maternal" mitochondria containing three and more new micromitochondria, increased as well. The use of mitoKATP blocker 5-hydroxydecanoate in parallel with uridine abolished its protective effect, as it significantly inhibited the formation of micromitochondria in rat cardiomyocytes after acute hypoxic exposure.

Binding affinity and decontamination of dermal decontamination gel to model chemical warfare agent simulants.

Six chemical warfare agent simulants (trimethyl phosphate, dimethyl adipate, 2-chloroethyl methyl sulfide, diethyl adipate, chloroethyl phenyl sulfide and diethyl sebacate) were studied in in vitro human skin to explore relationship between dermal penetration/absorption and the mechanisms of simulant partitioning between stratum corneum (SC) and water as well as between dermal decontamination gel (DDGel) and water. Both binding affinity to and decontamination of simulants using DDGel were studied. Partition coefficients of six simulants between SC and water (Log PSC/w ) and between DDGel and water (Log PDDGel/w ) were determined. Results showed that DDGel has a similar or higher binding affinity to each simulant compared to SC. The relationship between Log P octanol/water and Log PSC/w as well as between Log P octanol/water and Log PDDGel/w demonstrated that partition coefficient of simulants correlated to their lipophilicity or hydrophilicity. Decontamination efficiency results with DDGel for these simulants were consistent with binding affinity results. Amounts of percentage dose of chemicals in DDGel of trimethyl phosphate, dimethyl adipate, 2-chloroethyl methyl sulfide, diethyl adipate, chloroethyl phenyl sulfide and diethyl sebacate were determined to be 61.15, 85.67, 75.91, 53.53, 89.89 and 76.58, with corresponding amounts absorbed in skin of 0.96, 0.65, 1.68, 0.72, 0.57 and 1.38, respectively. In vitro skin decontamination experiments coupled with a dermal absorption study demonstrated that DDGel can efficiently remove chemicals from skin surface, back-extract from the SC, and significantly reduced chemical penetration into skin or systemic absorption for all six simulants tested. Therefore, DDGel offers a great potential as a NextGen skin Decon platform technology for both military and civilian use.

Anti-apoptotic and anti-inflammatory effects of hydrogen sulfide in a rat model of regional myocardial I/R.

Hydrogen sulfide (H2S) is a novel gaseous mediator produced by cystathionine-beta-synthase and cystathionine-gamma-lyase in the cardiovascular system, including the heart. Using a rat model of regional myocardial ischemia/reperfusion, we investigated the effects of an H2S donor (sodium hydrogen sulfide [NaHS]) on the infarct size and apoptosis caused by ischemia (25 min) and reperfusion (2 h). Furthermore, we investigated the potential mechanism(s) of the cardioprotective effect(s) afforded by NaHS. Specifically, we demonstrate that NaHS (1) attenuates the increase in caspase 9 activity observed in cardiac myocytes isolated from the area at risk (AAR) of hearts subjected in vivo to regional myocardial I/R and (2) ameliorates the decrease in expression of Bcl-2 within the AAR obtained from rat hearts subjected to regional myocardial I/R. The cardioprotective effects of NaHS were abolished by 5-hydroxydeconoate, a putative mitochondrial adenosine triphosphate-sensitive potassium channel blocker. Furthermore, NaHS attenuated the increase in the I/R-induced (1) phosphorylation of p38 mitogen-activated protein kinase and Jun N-terminal kinase, (2) translocation from the cytosol to the nucleus of the p65 subunit of nuclear factor-kappaB, (3) intercellular adhesion molecule 1 expression, (4) polymorphonuclear leukocyte accumulation, (5) myeloperoxidase activity, (6) malondialdehyde levels, and (7) nitrotyrosine staining determined in the AAR obtained from rat hearts subjected to regional myocardial I/R. In conclusion, we demonstrate that the cardioprotective effect of NaHS is secondary to a combination of antiapoptotic and anti-inflammatory effects. The antiapoptotic effect of NaHS may be in part due to the opening of the putative mitochondrial adenosine triphosphate-sensitive potassium channels.

Effect of some amino acids on the rectal irritation caused by sodium caprate in conscious rats.

The effects of some amino acids such as L-glutamine (Gln), L-arginine (Arg) and L-methionine (Met) on rectal irritation caused by sodium caprate were studied in rats. Rectal irritation was assessed by the balloon method in fasting conscious rats. This method is based on measuring rectal contractions due to possible irritation caused by the presence of drugs and/or adjuvants in the rectum. Strong contractions were observed after rectal administration of an aqueous solution of 100 mM sodium caprate. However, the presence of Gln, Arg or Met (100 mM) in sodium caprate (100 mM) solution resulted in a significant decrease in the intensity of the rectal contraction caused by sodium caprate. The rectal absorption-promoting effect of sodium caprate on 6-carboxyfluorescein (6-CF) was examined following administration with amino acids in rats. The absorption of 6-CF was not influenced by the concurrent administration of amino acids. In addition, the rectal tissue interaction of sodium caprate, with or without Gln, was examined. The concentration of sodium caprate in rectal tissue was reduced by the presence of Gln.

A cAMP-dependent protein kinase inhibitor modulates the blocking action of ATP and 5-hydroxydecanoate on the ATP-sensitive K+ channel.

We studied the blocking mechanism of 5-hydroxydecanoate, a novel antiarrhythmic agent, on the ATP-sensitive K+ channel in the single ventricular myocytes using the inside-out patch clamp technique. The channel activity in response to 5-hydroxydecanoate varied with each membrane patch corresponding to the sensitivity to ATP. In this condition the exogenous application of cAMP or cAMP-dependent protein kinase (PKA) obviously recovered the ATP-sensitive K+ channel activity after channel deactivation. By contrast, in membrane patches exhibited low sensitivity to ATP, endogenous cAMP-dependent protein kinase inhibitor (PKI) depressed the channel activity and restored the inhibitory action of 5-hydroxydecanoate and ATP on the channel. These results suggest that PKA-PKI system is involved in the regulatory mechanism of gating activity of the ATP-sensitive K+ channel and the blocking action of 5-hydroxydecanoate and ATP appears to be exerted by potentiating the inhibitory action of PKI on the channel.

Induction of human basophil histamine release by a novel protein kinase C activator, sn-1,2-isopropylidene-3-decanoyl-glycerol (IpOCOC9): partial characterization of secretagogue characteristics.

Human leukocytes were found to release histamine at exposure for the synthetic glyceride derivative sn-1,2-isopropylidene-3-decanoyl-glycerol (IpOCOC9). The following characteristics for the IpOCOC9-induced basophil histamine release were recorded. A. In the order of 25% of the cellular histamine content was extruded at 206 mumol/l and 45% at 690 mumol/l of the compound, respectively. B. Removal of extracellular Ca2+ variably affected IpOCOC9-triggered release. C. The presence of N-ethylmaleimide (10 mumol/l) or p-bromophenacylbromide (10 mumol/l) markedly reduced IpOCOC9-induced histamine release. D. The time course of the release triggered by IpOCOC9 was intermediate to those characterizing the release triggered by 4 beta-phorbol 12-myristate 13-acetate (PMA) and by formyl-methionyl-leucyl-phenylalanine (FMLP). E. Cells desensitized to IgE-receptor-mediated stimulation were hyperresponsive to stimulation with IpOCOC9. F. Cells treated with a low concentration of 2-deoxyglucose were not hyperresponsive to IpOCOC9. These data show that IpOCOC9, a PMN/leukocyte protein kinase C stimulator, acts as a non-cytotoxic secretagogue for human basophils with a mode of action which in some, but not all respects, mimics that of PMA. In particular, IpOCOC9-triggered release resembles that reported by other authors for hyperosmolar triggering of release by mannitol.