Polystyrene-b-poly (acrylic acid) nanovesicles coated by modified chitosans for encapsulation of minoxidil

Abstract In this work, polystyrene-b-poly (acrylic acid) (PS-b-PAA) nanovesicles were coated by modified chitosans aiming at studying its physicochemical parameters. The chitosan (CS) was chemically modified to add hydrophilic and/or hydrophobic groups, obtaining three modified chitosans. The PS-b-PAA nanovesicles were obtained by organic (1,4-dioxane) cosolvent method in water, resulting in nanovesicles with less than 150 nm of diameter (polydispersibility index - PDI at 90° = 0.106), measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and negative zeta potential (-37.5 ± 3.2 mV), allowing the coating of its surface with oppositely charged polysaccharides, such as the CS and the modified chitosans. The coating process was made by mixing the colloidal suspensions with the CS and the modified chitosans at specific ENT#091;CS-xENT#093;/ENT#091;PS-b-PAAENT#093; ratios (0.001 to 1.0 wt %) and measuring the change in size and surface charge by DLS and zeta potential. Upon reaching maximum adsorption, the zeta potential parameter was positively stabilized (+26.7 ± 4.1 mV) with a hydrodynamic diameter slightly longer (< 200 nm of diameter). The encapsulation efficiency (EE) of minoxidil, quantified by capillary electrophoresis, was 50.7%, confirming their potential as drug delivery carriers and the coating process showed the possibility of controlling the surface charge nature of these nanovesicles

KATP Channel Openers Inhibit Lymphatic Contractions and Lymph Flow as a Possible Mechanism of Peripheral Edema.

Pharmacological openers of ATP-sensitive potassium (KATP) channels are effective antihypertensive agents, but off-target effects, including severe peripheral edema, limit their clinical usefulness. It is presumed that the arterial dilation induced by KATP channel openers (KCOs) increases capillary pressure to promote filtration edema. However, KATP channels also are expressed by lymphatic muscle cells (LMCs), raising the possibility that KCOs also attenuate lymph flow to increase interstitial fluid. The present study explored the effect of KCOs on lymphatic contractile function and lymph flow. In isolated rat mesenteric lymph vessels (LVs), the prototypic KATP channel opener cromakalim (0.01-3 µmol/l) progressively inhibited rhythmic contractions and calculated intraluminal flow. Minoxidil sulfate and diazoxide (0.01-100 µmol/l) had similar effects at clinically relevant plasma concentrations. High-speed in vivo imaging of the rat mesenteric lymphatic circulation revealed that superfusion of LVs with cromakalim and minoxidil sulfate (0.01-10 µmol/l) maximally decreased lymph flow in vivo by 38.4% and 27.4%, respectively. Real-time polymerase chain reaction and flow cytometry identified the abundant KATP channel subunits in LMCs as the pore-forming Kir6.1/6.2 and regulatory sulfonylurea receptor 2 subunits. Patch-clamp studies detected cromakalim-elicited unitary K+ currents in cell-attached patches of LMCs with a single-channel conductance of 46.4 pS, which is a property consistent with Kir6.1/6.2 tetrameric channels. Addition of minoxidil sulfate and diazoxide elicited unitary currents of similar amplitude. Collectively, our findings indicate that KCOs attenuate lymph flow at clinically relevant plasma concentrations as a potential contributing mechanism to peripheral edema. SIGNIFICANCE STATEMENT: ATP-sensitive potassium (KATP) channel openers (KCOs) are potent antihypertensive medications, but off-target effects, including severe peripheral edema, limit their clinical use. Here, we demonstrate that KCOs impair the rhythmic contractions of lymph vessels and attenuate lymph flow, which may promote edema formation. Our finding that the KATP channels in lymphatic muscle cells may be unique from their counterparts in arterial muscle implies that designing arterial-selective KCOs may avoid activation of lymphatic KATP channels and peripheral edema.

LC-MS bioanalytical method for simultaneous determination of latanoprost and minoxidil in the skin.

The association of minoxidil sulphate and latanoprost is currently emerging as a promising strategy for the treatment of androgenic alopecia, which is the most common type of scalp hair loss. In order to support the development of new pharmaceutical products containing such drugs combination, this study proposes a simple and efficient LC-MS bioanalytical method to simultaneously quantify minoxidil sulphate and latanoprost in different skin layers. Compounds separation was performed by liquid chromatography using a C18 column with gradient elution of a mobile phase composed of 0.1 % formic acid in acetonitrile and water at a flow rate of 0.5 mL min-1. Determinations were executed using mass spectrometry equipped with an ESI interface operating in a positive ionization mode. Quantification was performed using selective ion mode monitoring of m/z 210.1 for minoxidil sulphate and 433.3 for latanoprost. The matrix effect was very pronounced in samples containing some skin layers or electrolyte solution. Accordingly, a calibration curve for each contaminant group was built, leading to correlation coefficient values higher than 0.99. Additionally, lower limits of detection and quantification were obtained, and precision (repeatability and intermediate precision) achieved results with a coefficient of variation less than 15 %. Drug recovery from skin samples was higher than 70 %, fulfilling the recommendations. Also, the bioanalytical method was successfully tested in in vitro skin penetration studies proving its effectiveness in the development of topical formulations containing both drugs.

Colored Polymeric Nanofiber Loaded with Minoxidil Sulphate as Beauty Coverage and Restoring Hair Loss.

Polymeric nanofibers fabricated by electrospinning either blank (PVA) or loaded with minoxidil sulphate have yielded optimum fibers with an average diameter 273 nm, and 511 nm, respectively. Thermal analysis of nanofibers indicated no chemical interaction. The NMR spectrum confirmed stability of nanofiber as there were no interactions between functional groups. Prepared nanofibers showed a 47.4% encapsulation efficiency and 73% yield. In vitro drug release of minoxidil sulphate from nanofiber exhibited an initial burst release followed by a slower release pattern. Stability studies revealed that minoxidil nanofiber was stable if stored at room temperature and protected from light with only loss of 9.6% of its nominal concentration within 6 months. As a result, the prepared solid/colored formula serves as an ideal formulation for such instable drug in liquid formula taking the advantage of the attractiveness of beauty colored coverage, and the simple, and non-tousled application.

Low-dose daily aspirin reduces topical minoxidil efficacy in androgenetic alopecia patients.

Topical minoxidil is the only US FDA approved OTC drug for the treatment of androgenetic alopecia (AGA). Minoxidil is a pro-drug converted into its active form, minoxidil sulfate, by the sulfotransferase enzymes in the outer root sheath of hair follicles. Previously, we demonstrated that sulfotransferase activity in hair follicles predicts response to topical minoxidil in the treatment of AGA. In the human liver, sulfotransferase activity is significantly inhibited by salicylic acid. Low-dose OTC aspirin (75-81 mg), a derivative of salicylic acid, is used by millions of people daily for the prevention of coronary heart disease and cancer. It is not known whether oral aspirin inhibits sulfotransferase activity in hair follicles, potentially affecting minoxidil response in AGA patients. In the present study, we determined the follicular sulfotransferase enzymatic activity following 14 days of oral aspirin administration. In our cohort of 24 subjects, 50% were initially predicted to be responders to minoxidil. However, following 14 days of aspirin administration, only 27% of the subjects were predicted to respond to topical minoxidil. To the best of our knowledge, this is the first study to report the effect of low-dose daily aspirin use on the efficacy of topical minoxidil.

Development and validation of rapid and simultaneous method for determination of 12 hair-growth compounds in adulterated products by UHPLC-MS/MS.

Synthetic hair-growth compounds have been illegally used in diverse products to enhance the short-term efficacy of these products. In this study, a rapid and simultaneous method for the determination of hair-growth compounds in adulterated products based on ultra high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The limit of detection (LOD) and limit of quantitation (LOQs) of the method were 0.08-43.6ng/mL and 0.27-145ng/mL for the solid-, liquid-, and cream-type samples, respectively. Good calibration linearity for all compounds was demonstrated with a correlation coefficient (r2) higher than 0.997. The intra- and inter-assay precisions were within 11%. The corresponding accuracies were 86-117% and 81-113%, respectively. The mean recoveries obtained for the solid-, liquid, and cream-type samples ranged from 87 to 114%, with a relative standard deviation (RSD) within 6%. The RSD of the stability evaluated at 4°C for 48h was less than 6%. The established method was used to screen 76 samples advertised as hair-growth treatments, from online and offline markets, over the course of two years. In 10% of the samples, four compounds, including triaminodil, minoxidil, finasteride, methyltestosterone, and testosterone-propionate were detected. The concentrations were in the range of 0.5-16.4mg/g. This technique provides a reliable platform for technical analysis for continuous monitoring of adulterated products to protect public health.

Isolation and structural identification of a novel minoxidil analogue in an illegal dietary supplement: triaminodil.

A new minoxidil analogue was detected in an illegal dietary supplement advertised as a hair-growth treatment. The analogue was identified using ultra-performance liquid chromatography (UPLC), high-resolution mass spectrometry (LC-HR-MS) and nuclear magnetic resonance (NMR) spectroscopy. The compound was structurally elucidated as a minoxidil analogue in which the piperidinyl group of minoxidil was replaced with a pyrrolidinyl group corresponding to a molecular formula of C8H13N5O. The new analogue has been named triaminodil. As this is the first report of the compound, there are no chemical, toxicology or pharmacological data available.

Iontophoresis of minoxidil sulphate loaded microparticles, a strategy for follicular drug targeting?

The feasibility of targeting drugs to hair follicles by a combination of microencapsulation and iontophoresis has been evaluated. Minoxidil sulphate (MXS), which is used in the treatment of alopecia, was selected as a relevant drug with respect to follicular penetration. The skin permeation and disposition of MXS encapsulated in chitosan microparticles (MXS-MP) was evaluated in vitro after passive and iontophoretic delivery. Uptake of MXS was quantified at different exposure times in the stratum corneum (SC) and hair follicles. Microencapsulation resulted in increased (6-fold) drug accumulation in the hair follicles relative to delivery from a simple MXS solution. Application of iontophoresis enhanced follicular delivery for both the solution and the microparticle formulations. It appears, therefore, that microencapsulation and iontophoresis can act synergistically to enhance topical drug targeting to hair follicles.

Chitosan nanoparticles for targeting and sustaining minoxidil sulphate delivery to hair follicles.

This work developed minoxidil sulphate-loaded chitosan nanoparticles (MXS-NP) for targeted delivery to hair follicles, which could sustain drug release and improve the topical treatment of alopecia. Chitosan nanoparticles were obtained using low-molecular weight chitosan and tripolyphosphate as crosslink agent. MXS-NP presented a monomodal distribution with hydrodynamic diameter of 235.5 ± 99.9 nm (PDI of 0.31 ± 0.01) and positive zeta potential (+38.6 ± 6.0 mV). SEM analysis confirmed nanoparticles average size and spherical shape. A drug loading efficiency of 73.0 ± 0.3% was obtained with polymer:drug ratio of 1:1 (w/w). Drug release through cellulose acetate membranes from MXS-NP was sustained in about 5 times in comparison to the diffusion rate of MXS from the solution (188.9 ± 6.0 µg/cm(2)/h and 35.4 ± 1.8 µg/cm(2)/h). Drug permeation studies through the skin in vitro, followed by selective recovery of MXS from the hair follicles, showed that MXS-NP application resulted in a two-fold MXS increase into hair follicles after 6h in comparison to the control solution (5.9 ± 0.6 µg/cm(2) and 2.9 ± 0.8 µg/cm(2)). MXS-loading in nanoparticles appears as a promising and easy strategy to target and sustain drug delivery to hair follicles, which may improve the topical treatment of alopecia.

Novel enzymatic assay predicts minoxidil response in the treatment of androgenetic alopecia.

Topical minoxidil is the most common drug used for the treatment of androgenetic alopecia (AGA) in men and women. Although topical minoxidil exhibits a good safety profile, the efficacy in the overall population remains relatively low at 30-40%. To observe significant improvement in hair growth, minoxidil is typically used daily for a period of at least 3-4 months. Due to the significant time commitment and low response rate, a biomarker for predicting patient response prior to therapy would be advantageous. Minoxidil is converted in the scalp to its active form, minoxidil sulfate, by the sulfotransferase enzyme SULT1A1. We hypothesized that SULT1A1 enzyme activity in the hair follicle correlates with minoxidil response for the treatment of AGA. Our preliminary retrospective study of a SULT1A1 activity assay demonstrates 95% sensitivity and 73% specificity in predicting minoxidil treatment response for AGA. A larger prospective study is now under way to further validate this novel assay.

Minoxidil sulfate induced the increase in blood-brain tumor barrier permeability through ROS/RhoA/PI3K/PKB signaling pathway.

Adenosine 5'-triphosphate-sensitive potassium channel (KATP channel) activator, minoxidil sulfate (MS), can selectively increase the permeability of the blood-tumor barrier (BTB); however, the mechanism by which this occurs is still under investigation. Using a rat brain glioma (C6) model, we first examined the expression levels of occludin and claudin-5 at different time points after intracarotid infusion of MS (30 µg/kg/min) by western blotting. Compared to MS treatment for 0 min group, the protein expression levels of occludin and claudin-5 in brain tumor tissue of rats showed no changes within 1 h and began to decrease significantly after 2 h of MS infusion. Based on these findings, we then used an in vitro BTB model and selective inhibitors of diverse signaling pathways to investigate whether reactive oxygen species (ROS)/RhoA/PI3K/PKB pathway play a key role in the process of the increase of BTB permeability induced by MS. The inhibitor of ROS or RhoA or PI3K or PKB significantly attenuated the expression of tight junction (TJ) protein and the increase of the BTB permeability after 2 h of MS treatment. In addition, the significant increases in RhoA activity and PKB phosphorylation after MS administration were observed, which were partly inhibited by N-2-mercaptopropionyl glycine (MPG) or C3 exoenzyme or LY294002 pretreatment. The present study indicates that the activation of signaling cascades involving ROS/RhoA/PI3K/PKB in BTB was required for the increase of BTB permeability induced by MS. Taken together, all of these results suggested that MS might increase BTB permeability in a time-dependent manner by down-regulating TJ protein expression and this effect could be related to ROS/RhoA/PI3K/PKB signal pathway.

Iontophoresis-targeted, follicular delivery of minoxidil sulfate for the treatment of alopecia.

Although minoxidil (MX) is a drug known to stimulate hair growth, the treatment of androgenic alopecia could be improved by delivery strategies that would favor drug accumulation into the hair follicles. This work investigated in vitro the potential of iontophoresis to achieve this objective using MX sulfate (MXS), a more water-soluble derivative of MX. Passive delivery of MXS was first determined from an ethanol-water solution and from a thermosensitive gel. The latter formulation resulted in greater accumulation of MXS in the stratum corneum (skin's outermost layer) and hair follicles and an overall decrease in absorption through the skin. Anodal iontophoresis of MXS from the same gel formulation was then investigated at pH 3.5 and pH 5.5. Compared with passive delivery, iontophoresis increased the amount of drug reaching the follicular infundibula from 120 to 600 ng per follicle. In addition, drug recovery from follicular casts was threefold higher following iontophoresis at pH 5.5 compared with that at pH 3.5. Preliminary in vivo experiments in rats confirmed that iontophoretic delivery of MXS facilitated drug accumulation in hair follicles. Overall, therefore, iontophoresis successfully and significantly enhanced follicular delivery of MX suggesting a useful opportunity for the improved treatment of alopecia.

Chitosan microparticles for sustaining the topical delivery of minoxidil sulphate.

Given the hypothesis that microparticles can penetrate the skin barrier along the transfollicular route, this work aimed to obtain and characterise chitosan microparticles loaded with minoxidil sulphate (MXS) and to study their ability to sustain the release of the drug, attempting a further application utilising them in a targeted delivery system for the topical treatment of alopecia. Chitosan microparticles, containing different proportions of MXS/polymer, were prepared by spray drying and were characterised by yield, encapsulation efficiency, size and morphology. Microparticles selected for further studies showed high encapsulation efficiency (∼82%), a mean diameter of 3.0 µm and a spherical morphology without porosities. When suspended in an ethanol/water solution, chitosan microparticles underwent instantaneous swelling, increasing their mean diameter by 90%. Release studies revealed that the chitosan microparticles were able to sustain about three times the release rate of MXS. This feature, combined with suitable size, confers to these microparticles the potential to target and improve topical therapy of alopecia with minoxidil.

Adenosine 5'-triphosphate-sensitive potassium channel activator induces the up-regulation of caveolin-1 expression in a rat brain tumor model.

This study was performed to determine whether minoxidil sulfate (MS), a selective Adenosine 5'-triphosphate-sensitive potassium channel (K (ATP) channel) activator, has an effect on the expression of caveolin-1 in the rat's brain tumor tissue. Using a rat brain glioma (C6) model, we found that the expression of caveolin-1 protein at tumor sites was greatly increased after intracarotid infusion of MS at a dose of 30 µg/kg/min for 15, 30, and 60 min via Western blot analysis. And the peak value of the caveolin-1 expression was observed in rats with glioma after 15 min of MS perfusion, which was significantly attenuated by reactive oxygen species (ROS) scavenger (N-2-mercaptopropionyl glycine, MPG). In addition, MPG also significantly inhibited the increase of blood-brain tumor barrier (BTB) permeability which was induced by MS. This led to the conclusion that the MS-induced BTB permeability increase may be related to the accelerated formation of caveolin-1 protein, and could be mediated by ROS.

Activation of KATP channels increases anticancer drug delivery to brain tumors and survival.

Several anticancer drugs are ineffective against brain tumor and do not impact patient survival because they fail to cross the blood-brain tumor barrier (BTB) effective levels. One such agent temozolomide is commonly used in brain tumor patients, which works better when combined with radiation or other anticancer agents. Likewise, trastuzumab (Herceptin, Her-2 inhibitor), which might be effective against Her2/neu over expressing gliomas may work well when combined with temozolomide. Nonetheless, both drugs do not cross the BTB to significantly impact patient survival. Beforehand we showed that potassium channel agonists when intracarotidly administered increased carboplatin and Her-2 antibody delivery in animal glioma models by triggering formation of brain vascular endothelial transcytotic vesicles. In this study, we investigated whether, intravenously administered, ATP-sensitive potassium channel (K(ATP)) activator (minoxidil sulfate; MS) increases temozolomide and Herceptin delivery to brain tumors to induce anti-tumor activity and increase survival in nude mice with Glioblastoma multiforme (GBM) cells. The results clearly demonstrate that when given intravenously temozolomide crosses BTB at a relatively low amount while Herceptin failed to cross the BTB. However, MS co-infusion with [(14)C]-temozolomide or fluorescently labeled-Herceptin resulted in improved and selective drug delivery to brain tumor. We also showed that combination treatment with temozolomide and Herceptin has enhanced anti-tumor effect which was more prominent than that of either treatment alone in increasing the survival in mice with GBM when co-infused with MS. Therefore, brain tumor patients may be benefited when anti-neoplastic agent delivery is increased selectively to the brain tumors using KATP channel agonists.

Attenuation of receptor-dependent and -independent vasoconstriction in the human radial artery.

BACKGROUND: Vasodilator strategies used to treat bypass grafts in the operating theatre, such as nitrates, phosphodiesterase inhibitors and calcium channel antagonists have a broad but short-lived effect against a variety of vasoconstrictor stimuli. Treatments that react irreversibly with proteins modulating vasoconstriction have the advantage that their effects can last well into the postoperative period. In addition systemic effects are avoided as the treatment is localised to the treated graft. This study investigated the use of two clinically applied drugs; fluphenazine (SKF7171A, HCl), an irreversible calmodulin antagonist and minoxidil sulphate, an irreversible potassium channel opener. Treatments were tested against receptor and non-receptor-mediated contraction in the human radial artery. METHOD: Isometric tension was measured in response to angiotensin II, KCl and vasopressin in 108 radial artery rings (taken from 31 patients undergoing coronary artery bypass grafting). Control responses were compared with rings pretreated with fluphenazine or minoxidil sulphate. Vasopressin responses were also compared in the presence of glyceryl trinitrate or the reversible Rho kinase inhibitor Y27632. RESULTS: Fluphenazine pretreatment significantly suppressed vasoconstriction to all agonists tested. Maximal responses to angiotensin II, vasopressin and KCl were reduced by 42+/-19%, 35+/-8% and 48+/-15% respectively, without any measurable effect on the EC(50). Minoxidil sulphate showed no discernable effect. Vasopressin-induced contraction was also reduced by high levels of glyceryl trinitrate (220 microM; 50 microg/ml) or 10 microM Y27632. CONCLUSIONS: The irreversible calmodulin antagonist fluphenazine has potential to be developed as an inhibitor of contraction in arterial graft vessels. The involvement of Rho kinase indicates that other vasoconstrictors and surgical stress can sensitize radial artery to vasopressin-induced contraction. Strategies targeting this pathway also have future potential.

Different effects of KCa and KATP agonists on brain tumor permeability between syngeneic and allogeneic rat models.

The blood-brain tumor barrier (BTB) significantly limits delivery of effective concentrations of chemotherapeutic drugs to brain tumors. Previous studies suggest that BTB permeability may be modulated via alteration in the activity of potassium channels. In this study, we studied the relationship of BTB permeability increase mediated by potassium channel agonists to channel expression in two rat brain tumor models. Intravenous infusion of KCO912 (K(ATP) agonist), minoxidil sulfate (K(ATP) agonist) or NS1619 (K(Ca) agonist) increased tumor permeability more in the 9L allogeneic brain tumor model than in the syngeneic brain tumor model. Consistently, expression of both K(ATP) and K(Ca) channels in 9L tumors was increased to a significantly greater extent in Wistar rats (allogeneic) as compared to Fischer rats (syngeneic). Furthermore, as a preliminary effort to understand clinical implication of potassium channels in brain tumor treatment, we determined the expression of K(ATP) in surgical specimens. K(ATP) mRNA was detected in glioblastoma multiforme (GBM) from nineteen patients examined, with a wide range of expression levels. Interestingly, in paired GBM tissues from seven patients before and after vaccination therapy, increased levels of K(ATP) were detected in five patients after vaccination that had positive response to chemotherapy after vaccination. The present study indicates that the effects of potassium channel agonists on BTB permeability are different between syngeneic and allogeneic models which have different expression levels of potassium channels. The expression of potassium channels in brain tumors is variable, which may be associated with different tumor permeability to therapeutic agents among patients.

Adenosine 5'-triphosphate-sensitive potassium channel-mediated blood-brain tumor barrier permeability increase in a rat brain tumor model.

Brain tumor microvessels/capillaries limit drug delivery to tumors by forming a blood-brain tumor barrier (BTB). The BTB overexpresses ATP-sensitive potassium (K(ATP)) channels that are barely detectable in normal brain capillaries, and which were targeted for BTB permeability modulation. In a rat brain tumor model, we infused minoxidil sulfate (MS), a selective K(ATP) channel activator, to obtain sustained, enhanced, and selective drug delivery, including various sized molecules, across the BTB to brain tumors. Glibenclamide, a selective K(ATP) channel inhibitor, significantly attenuated the MS-induced BTB permeability increase. Immunocytochemistry and glibenclamide binding studies showed increased K(ATP) channel density distribution on tumor cells and tumor capillary endothelium, which was confirmed by K(ATP) channel potentiometric assay in tumor cells and brain endothelial cells cocultured with brain tumor cells. MS infusion in rats with brain tumors significantly increased transport vesicle density in tumor capillary endothelial and tumor cells. MS facilitated increased delivery of macromolecules, including Her-2 antibody, adenoviral-green fluorescent protein, and carboplatin, to brain tumors, with carboplatin significantly increasing survival in brain tumor-bearing rats. K(ATP) channel-mediated BTB permeability increase was also demonstrated in a human, brain tumor xenograft model. We conclude that K(ATP) channels are a potential target for biochemical modulation of BTB permeability to increase antineoplastic drug delivery selectively to brain tumors.

Reduction of potassium currents and phosphatidylinositol 3-kinase-dependent AKT phosphorylation by tumor necrosis factor-(alpha) rescues axotomized retinal ganglion cells from retrograde cell death in vivo.

Tumor-necrosis-factor-alpha (TNF-alpha) prevented secondary death of retinal ganglion cells (RGCs) after axotomy of the optic nerve in vivo. This RGC rescue was confirmed in vitro in a mixed retinal culture model. In accordance with our previous findings, TNF-alpha decreased outward potassium currents in RGCs. Antagonism of the TNF-alpha-induced decrease in outward potassium currents with the potassium channel opener minoxidilsulfate (as verified by electrophysiology) abolished neuroprotection. Western blot analysis revealed an upregulation of phospho-Akt as a consequence of TNF-alpha-induced potassium current reduction. Inhibition of the phosphatidylinositol 3-kinase-Akt pathway with wortmannin decreased TNF-alpha-promoted RGC survival. These data point to a functionally relevant cytokine-dependent neuroprotective signaling cascade in adult CNS neurons.

New windows on the mechanism of action of K(ATP) channel openers.

K(ATP) channel openers are a diverse group of drugs with a wide range of potential therapeutic uses. Their molecular targets, the K(ATP) channels, exhibit tissue-specific responses because they possess different types of regulatory sulfonylurea receptor subunits. It is well recognized that complex interactions occur between K(ATP) channel openers and nucleotides, but the cloning of the K(ATP) channel has introduced a new dimension to the study of these events and has furthered our understanding of the molecular basis of the action of K(ATP) channel openers.