Efavirenz affects the bioenergetics of neurons through a mechanism involving acute mitochondrial inhibition, an action exacerbated in neuroinflammatory conditions. A similar scenario of glial cells survival and degeneration of neurons with signs of mitochondrial dysfunction and oxidative stress has been associated with neurocognitive disorders.

1 Selective phosphodiesterase 4 (PDE4) inhibitors are of potential interest in the treatment of asthma. We examined the eects of the alkaloid S-(+)-glaucine, a PDE4 inhibitor, on human isolated bronchus and granulocyte function. 2 Glaucine selectively inhibited PDE4 from human bronchus and polymorphonuclear leukocytes (PMN) in a non-competitive manner (K i =3.4 mM). Glaucine displaced [ 3 H]-rolipram from its highanity binding sites in rat brain cortex membranes (IC 50 *100 mM). 3 Glaucine inhibited the spontaneous and histamine-induced tone in human isolated bronchus (pD 2 *4.5). Glaucine (10 mM) did not potentiate the isoprenaline-induced relaxation but augmented cyclic AMP accumulation by isoprenaline. The glaucine-induced relaxation was resistant to H-89, a protein kinase A inhibitor. Glaucine depressed the contractile responses to Ca 2+ (pD' 2 *3.62) and reduced the sustained rise of [Ca 2+ ] i produced by histamine in cultured human airway smooth muscle cells (7log IC 50 *4.3). 4 Glaucine augmented cyclic AMP levels in human polymorphonuclear leukocytes challenged with N-formyl-Met-Leu-Phe (FMLP) or isoprenaline, and inhibited FMLP-induced superoxide generation, elastase release, leukotriene B 4 production, [Ca 2+ ] i signal and platelet aggregation as well as opsonized zymosan-, phorbol myristate acetate-, and A23187-induced superoxide release. The inhibitory eect of glaucine on superoxide generation by FMLP was reduced by H-89. 5 In conclusion, Ca 2+ channel antagonism by glaucine appears mainly responsible for the relaxant eect of glaucine in human isolated bronchus while PDE4 inhibition contributes to the inhibitory eects of glaucine in human granulocytes. The very low PDE4/binding site ratio found for glaucine makes this compound attractive for further structure-activity studies.

1 This study aimed to investigate the 5-hydroxytryptamine (5-HT) receptors mediating contraction of ring preparations isolated from human pulmonary arteries and veins. In functional studies, the responses to 5-HT, sumatriptan, ergotamine, serotonin-O-carboxymethyl-glycyl-tyrosinamide (SCMGT), a-methyl 5-HT (a-Me) and 2-methyl 5-HT (2-Me) were studied with WAY100635, GR127935, ritanserin, zacopride and SB204070 as antagonists. 2 All agonists produced concentration-dependent contractions of human pulmonary artery and vein preparations. The order of potency (7log EC 50 values) was ergotamine (6.88)45-HT (6.41)5SCMGT (6.20)=sumatriptan (6.19) 5a-Me (6.04) in the artery, and ergotamine (7.84)45-HT (6.96)4suma-triptan (6.60)=a-Me (6.56)4SCMGT (6.09) in the vein. The potency of each agonist, except for SCMGT, was greater in vein than in artery preparations. Contractile responses to 5-HT were similar in intact and endothelium-denuded preparations but responses to sumatriptan were enhanced in artery rings without endothelium. 3 GR127935 (1 nM to 0.5 mM) produced an unsurmountable antagonism of the response to 5-HT, sumatriptan, ergotamine and SCMGT. Ritanserin (1 nM to 1 mM) also reduced the maximum contractile responses to 5-HT, ergotamine and a-Me in artery and vein preparations without aecting those to sumatriptan and SCMGT. In endothelium-denuded preparations, surmountable antagonism of sumatriptan by GR127935 (in the presence of ritanserin) and of a-Me by ritanserin (in the presence of GR127935) allowed for the calculation of the apparent pK B values of GR127935 (9.17+0.11 in artery and 9.11+0.05 in vein) and ritanserin (8.82+0.09 in artery and 8.98+0.12 in vein). 4 WAY100635 (1 nM to 1 mM), zacopride (1 nM to 1 mM), or SB204070 (1 nM) did not signi®cantly alter the concentration-response curves for 5-HT, sumatriptan, ergotamine, SCMGT or 2-Me in human pulmonary artery or vein thus indicating that 5-HT 1A , 5-HT 3 and 5-HT 4 receptors are presumably not involved in the contractile response to these agonists. 5 Binding studies using selective radioligands for dierent 5-HT receptors could not detect the presence of 5-HT 1A receptor binding in human pulmonary blood vessels whereas the 5-HT 1B/1D radioligand [ 3 H]-5-CT signi®cantly labelled a population of speci®c binding sites in both vessel types. The presence of 5-HT 2A receptors could also be inferred from the level of binding of [ 3 H]-ketanserin to membranes obtained from human pulmonary vessels, although signi®cance could not be reached for arteries. 5-HT 4 speci®c receptor binding was scarce in veins and absent in the case of arteries. 6 These ®ndings indicate that the human pulmonary artery and vein have a mixed functional population of 5-HT 1B/1D and 5-HT 2A receptors mediating the contractile response to 5-HT which is consistent with results of the binding studies.

It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3-300 nM) and phorbol myristate acetate (160 pm-160 nM) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcysteine (33-333 microM) resulted in concentration-related inhibition of superoxide production induced by FMLP (30 nM) or phorbol myristate acetate (16 nM);-log IC50 values were 3.97 +/- 0.07 and 3.91 +/- 0.10, respectively. Changes in intracellular calcium ion concentration ([Ca2+]i) induced by FMLP (30 nM) were studied in fura-2-loaded human PMN. FMLP produced a transient calcium response, i.e. a peak followed by decay to a residual value above baseline. N-Acetylcysteine (333 microM) did not affect either basal [Ca2+]i values or changes in [Ca2+]i values after treatment with FMLP. Activation by phorbol myristate acetate caused a reduction in glutathione levels from 5.94 +/- 0.86 (control) to 1.84 +/- 0.51 nmol/3 x 10(6) cells (P < 0.05 compared with control). Pre-treatment with N-acetylcysteine (333 microM) fully reversed the reduction in glutathione levels induced by phorbol myristate acetate (4.83 +/- 0.68 nmol/3 x 10(6) cells; P > 0.05 compared with control). Exposure to t-butyl hydroperoxide (0.5 mM, 30 min) markedly increased malondialdehyde levels (from 0.03 +/- 0.02 to 0.73 +/- 0.07 nmol/10(6) cells), and index of lipid peroxidation. Malondialdehyde levels were significantly reduced in PMN treated with N-acetylcysteine (333 microM; 0.55 +/- 0.04 nmol/10(6) cells; P < 0.05 compared with untreated cells exposed to t-butyl hydroperoxide). In conclusion, N-acetylcysteine reduces superoxide generation in response to FMLP and phorbol myristate acetate and partially protects against lipid peroxidation in PMN from man. The protection afforded by N-acetylcysteine is not related to alteration of the intracellular calcium signal but might be effected by replenishment of the intracellular glutathione levels.

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