Pathophysiological Role of Mitochondrial Potassium Channels and their Modulation by Drugs

BACKGROUND

Mitochondria play a central role in ATP-generating processes. Indeed, in mammalian tissues, up to 90% of ATP is generated by mitochondria through the process of oxidative phosphorylation; furthermore, mitochondria are involved in multiple signal transduction pathways. A rapidly expanding body of literature has confirmed that mitochondria play a pivotal role in apoptosis, cardio- and neuro-protection, and various neurodegenerative disorders, ranging from Parkinson's to Alzheimer's disease. Mitochondria are also the targets of multiple drugs, some of these are specifically designed to affect mitochondrial function, while others have primary targets in other cellular locations but may interact with mitochondria because of the presence of numerous targets on this organelle. In this regard, mitochondrial potassium (mitoK) channels play a critical role in mitochondrial function and, consequently, in the metabolism of the whole cell.

OBJECTIVE

To describe mitoK channels from a structural point of view and investigate their pathophysiological roles, focusing on possible specific modulators that might be useful as pharmacological tools in the treatment of various pathologies characterized by mitoK involvement.

RESULTS

mitoK channels play a decisive role in several pathologies, including cardiovascular diseases, particularly in myocardial infarction and neurodegenerative diseases, and they are emerging as promising oncological targets.

CONCLUSIONS

mitoK channels represent novel targets, and mitoK channel modulators represent an exciting tool for pharmacological intervention against such pathological conditions.

Mitochondriotropic and Cardioprotective Effects of Triphenylphosphonium-Conjugated Derivatives of the Diterpenoid Isosteviol

Mitochondria play a crucial role in the cell fate; in particular, reducing the accumulation of calcium in the mitochondrial matrix offers cardioprotection. This affect is achieved by a mild depolarization of the mitochondrial membrane potential, which prevents the assembly and opening of the mitochondrial permeability transition pore. For this reason, mitochondria are an attractive target for pharmacological interventions that prevent ischaemia/reperfusion injury. Isosteviol is a diterpenoid created from the acid hydrolysis of Stevia rebaudiana Bertoni (fam. Asteraceae) glycosides that has shown protective effects against ischaemia/reperfusion injury, which are likely mediated through the activation of mitochondrial adenosine tri-phosphate (ATP)-sensitive potassium (mitoKATP) channels. Some triphenylphosphonium (triPP)-conjugated derivatives of isosteviol have been developed, and to evaluate the possible pharmacological benefits that result from these synthetic modifications, in this study, the mitochondriotropic properties of isosteviol and several triPP-conjugates were investigated in rat cardiac mitochondria and in the rat heart cell line H9c2. This study’s main findings highlight the ability of isosteviol to depolarize the mitochondrial membrane potential and reduce calcium uptake by the mitochondria, which are typical functions of mitochondrial potassium channel openings. Moreover, triPP-conjugated derivatives showed a similar behavior to isosteviol but at lower concentrations, indicative of their improved uptake into the mitochondrial matrix. Finally, the cardioprotective property of a selected triPP-conjugated derivative was demonstrated in an in vivo model of acute myocardial infarct.

Using hydrogen sulfide to design and develop drugs

INTRODUCTION

Hydrogen sulfide (H2S) is an endogenous gasotransmitter, involved in the regulation of several biological functions. Conversely, impaired biosynthesis of H2S is associated with important diseases. This paves the way for exciting pharmacological perspectives for drugs acting on the 'H2S system'.

AREAS COVERED

At the beginning of this manuscript, the authors present the biological roles and mechanisms of action of hydrogen sulfide. The authors then discuss the developments in the modulation of the H2S system via heterogeneous molecules, which behave as sources of exogenous H2S, and are promising drugs for a number of diseases.

EXPERT OPINION

The rate of H2S generation, the physicochemical characteristics and the bioavailability greatly affect the overall pharmacological profile of each H2S-releasing compound. Therefore, the development of broad collections of original moieties endowed with heterogeneous rates/mechanisms of H2S release and a variety of physicochemical, biological and pharmacological features is the most timely and compelling issue in the field of H2S-based drug discovery.

Design and synthesis of 2-oxindole based multi-targeted inhibitors of PDK1/Akt signaling pathway for the treatment of glioblastoma multiforme

Aggressive behavior and diffuse infiltrative growth are the main features of Glioblastoma multiforme (GBM), together with the high degree of resistance and recurrence. Evidence indicate that GBM-derived stem cells (GSCs), endowed with unlimited proliferative potential, play a critical role in tumor development and maintenance. Among the many signaling pathways involved in maintaining GSC stemness, tumorigenic potential, and anti-apoptotic properties, the PDK1/Akt pathway is a challenging target to develop new potential agents able to affect GBM resistance to chemotherapy. In an effort to find new PDK1/Akt inhibitors, we rationally designed and synthesized a small family of 2-oxindole derivatives. Among them, compound 3 inhibited PDK1 kinase and downstream effectors such as CHK1, GS3Kα and GS3Kβ, which contribute to GCS survival. Compound 3 appeared to be a good tool for studying the role of the PDK1/Akt pathway in GCS self-renewal and tumorigenicity, and might represent the starting point for the development of more potent and focused multi-target therapies for GBM.

Salbutamol inhibits RhoA activation in normal but not in desensitized bronchial smooth muscle cells

OBJECTIVE

This study was aimed at investigating whether the β2 -adrenoceptor agonist, salbutamol, could modulate RhoA activation in normal and homologously desensitized bronchial smooth muscle cells (BSMC).

METHODS

Serum-starved BSMCs were stimulated with the Rho-activating compound calpeptin in the presence or absence of salbutamol, the Epac activator, 8-pCPT-2'-O-Me-cAMP, or the site-selective activator of cAMP-dependent protein kinase A (PKA), 6-Bnz-cAMP. Activated RhoA was assessed by immunocytochemical detection and by RhoA G-LISA assay.

KEY FINDINGS

Stimulation with calpeptin caused translocation of RhoA from cytosol to plasma membrane, a condition required for the functional coupling of RhoA with its cellular targets. Pretreatment with salbutamol 10 μm for 15 min was found to block calpeptin-induced activation of RhoA in normal, but not in homologously desensitized cells. Pretreatment of calpeptin-stimulated BSMC with 8-pCPT-2'-O-Me-cAMP or 6-Bnz-cAMP could reproduce the effect of salbutamol.

CONCLUSIONS

These findings demonstrated that salbutamol inhibits RhoA activation in human BSMC through β2 -adrenoceptor/Epac/PKA pathway. An important pharmacological implication of these finding is the possible contribution of RhoA pathway to the molecular mechanism involved in airway smooth muscle relaxation caused by acute/chronic exposure to β2-adrenoceptor agonists.

Different patterns of H2S/NO activity and cross-talk in the control of the coronary vascular bed under normotensive or hypertensive conditions

Hydrogen sulfide (H2S) and nitric oxide (NO) play pivotal roles in the cardiovascular system. Conflicting results have been reported about their cross-talk. This study investigated their interplays in coronary bed of normotensive (NTRs) and spontaneously hypertensive rats (SHRs). The effects of H2S- (NaHS) and NO-donors (sodium nitroprusside, SNP) on coronary flow (CF) were measured in Langendorff-perfused hearts of NTRs and SHRs, in the absence or in the presence of propargylglycine (PAG, inhibitor of H2S biosynthesis), L-NAME (inhibitor of NO biosynthesis), ODQ (inhibitor of guanylate cyclase), L-Cysteine (substrate for H2S biosynthesis) or L-Arginine (substrate for NO biosynthesis). In NTRs, NaHS and SNP increased CF; their effects were particularly evident in Angiotensin II (AngII)-contracted coronary arteries. The dilatory effects of NaHS were abolished by L-NAME and ODQ; conversely, PAG abolished the effects of SNP. In SHRs, high levels of myocardial ROS production were observed. NaHS and SNP did not reduce the oxidative stress, but produced clear increases of the basal CF. In contrast, in AngII-contracted coronary arteries of SHRs, significant hyporeactivity to NaHS and SNP was observed. In SHRs, the vasodilatory effects of NaHS were only modestly affected by L-NAME and ODQ; PAG poorly influenced the effects of SNP. Then, in NTRs, the vascular actions of H2S required NO and vice versa. By contrast, in SHRs, the H2S-induced actions scarcely depend on NO release; as well, the NO effects are largely H2S-independent. These results represent the first step for understanding pathophysiological mechanisms of NO/H2S interplays under both normotensive and hypertensive conditions.

Hydrogen sulfide releasing capacity of natural isothiocyanates: is it a reliable explanation for the multiple biological effects of Brassicaceae?

Hydrogen sulfide is an endogenous pleiotropic gasotransmitter, which mediates important physiological effects in the human body. Accordingly, an impaired production of endogenous hydrogen sulfide contributes to the pathogenesis of important disorders. To date, exogenous compounds, acting as hydrogen sulfide-releasing agents, are viewed as promising pharmacotherapeutic agents. In a recent report, the hydrogen sulfide-releasing properties of some synthetic aryl isothiocyanate derivatives have been reported, indicating that the isothiocyanate function can be viewed as a suitable slow hydrogen sulfide-releasing moiety, endowed with the pharmacological potential typical of this gasotransmitter. Many isothiocyanate derivatives (deriving from a myrosinase-mediated transformation of glucosinolates) are well-known secondary metabolites of plants belonging to the family Brassicaceae, a large botanical family comprising many edible species. The phytotherapeutic and nutraceutic usefulness of Brassicaceae in the prevention of important human diseases, such as cancer, neurodegenerative processes and cardiovascular diseases has been widely discussed in the scientific literature. Although these effects have been largely attributed to isothiocyanates, the exact mechanism of action is still unknown. In this experimental work, we aimed to investigate the possible hydrogen sulfide-releasing capacity of some important natural isothiocyanates, studying it in vitro by amperometric detection. Some of the tested natural isothiocyanates exhibited significant hydrogen sulfide release, leading us to hypothesize that hydrogen sulfide may be, at least in part, a relevant player accounting for several biological effects of Brassicaceae.

Synergistic interaction between PPAR ligands and salbutamol on human bronchial smooth muscle cell proliferation

BACKGROUND AND PURPOSE

An important objective in asthma therapy is to prevent the accelerated growth of airway smooth muscle cells which leads to hyperplasia and bronchial hyperreactivity. We investigated the effect of combination of salbutamol and PPARγ agonists on growth factor-stimulated human bronchial smooth muscle cell (BSMC) proliferation.

EXPERIMENTAL APPROACH

Synergism was quantified by the combination index-isobologram method. Assays used here included analyses of growth inhibition, cell viability, DNA fragmentation, gene transcription, cell cycle and protein expression.

KEY RESULTS

The PPARγ gene was highly expressed in BSMC and the protein was identified in cell nuclei. Single-agent salbutamol or PPARγ agonists prevented growth factor-induced human BSMC proliferation within a micromolar range of concentrations through their specific receptor subtypes. Sub-micromolar levels of combined salbutamol-PPARγ agonist inhibited growth by 50% at concentrations from ∼2 to 12-fold lower than those required for each drug alone, without induction of apoptosis or necrosis. Combination treatments also promoted cell cycle arrest at the G1/S transition phase and inhibition of ERK phosphorylation.

CONCLUSIONS AND IMPLICATIONS

The synergistic interaction between PPARγ agonists and β(2) -adrenoceptor agonists on airway smooth muscle cell proliferation highlights the anti-remodelling potential of this combination in chronic lung diseases.

Synthesis of Novel 3,5-Disubstituted-2-oxindole Derivatives As Antitumor Agents against Human Nonsmall Cell Lung Cancer

This study was aimed at investigating the antitumor activity of novel 2-oxindole derivatives against a well-characterized human nonsmall cell lung cancer (NSCLC) cell line. Test compounds produced an antiproliferative activity in the low micromolar/submicromolar range of concentrations and significantly induced typical apoptotic morphology with cell shrinkage, nuclear condensation and fragmentation, and rupture of cells into debris in a relatively low percentage of A549 cells. Cell cycle arrest occurred at the G1/S phase (1a and 2), and Akt phosphorylation was significantly inhibited at Thr308 and Ser473. The most active compound (1a) has an IC50 6-fold lower than the Akt inhibitor, perifosine. These data suggest that the new compounds may be cytostatic and may have maximum clinical effects in NSCLC patients who do not respond to EGFR inhibitors. These findings prompt us to further explore the oxindole structure as leading scaffold to design new molecules with potent antitumor activity against NSCLC.

Arylthioamides as H2S Donors: l-Cysteine-Activated Releasing Properties and Vascular Effects in Vitro and in Vivo

A small library of arylthioamides 1-12 was easily synthesized, and their H2S-releasing properties were evaluated both in the absence or in the presence of an organic thiol such as l-cysteine. A number of arylthioamides (1-3 and 7) showed a slow and l-cysteine-dependent H2S-releasing mechanism, similar to that exhibited by the reference slow H2S-releasing agents, such as diallyl disulfide (DADS) and the phosphinodithioate derivative GYY 4137. Compound 1 strongly abolished the noradrenaline-induced vasoconstriction in isolated rat aortic rings and hyperpolarized the membranes of human vascular smooth muscle cells in a concentration-dependent fashion. Finally, a significant reduction of the systolic blood pressure of anesthetized normotensive rats was observed after its oral administration. Altogether these results highlighted the potential of arylthioamides 1-3 and 7 as H2S-donors for basic studies, and for the rational design/development of promising pharmacotherapeutic agents to treat cardiovascular diseases.

The activation of mitochondrial BK potassium channels contributes to the protective effects of naringenin against myocardial ischemia/reperfusion injury

Naringenin (NAR), flavonoid abundant in the genus Citrus, has been reported to interact with the large-conductance calcium-activated potassium channels (BK). Since activators of BK channels expressed in cardiac mitochondria trigger protective effects in several models of myocardial ischemia/reperfusion (I/R), this work aimed to evaluate the potential cardioprotective effects of NAR and the involvement of mitochondrial BK channels. In an in vivo model of acute infarct in rats, NAR (100mg/kg i.p.) significantly reduced the heart injury induced by I/R. This effect was antagonized by the selective BK-blocker paxilline (PAX). The cardioprotective dose of NAR did not cause significant effects on the blood pressure. In Largendorff-perfused rat hearts submitted to ischemia/reperfusion, NAR improved the post-ischemic functional parameters (left ventricle developed pressure and dP/dt) with lower extension of myocardial injury. On isolated rat cardiac mitochondria, NAR caused a concentration-dependent depolarization of mitochondrial membrane and caused a trans-membrane flow of thallium (potassium-mimetic cation). Both these effects were antagonized by selective blockers of BK channels. Furthermore, NAR half-reduced the calcium accumulation into the matrix of cardiac mitochondria exposed to high calcium concentrations. In conclusion, NAR exerts anti-ischemic effects through a "pharmacological preconditioning" that it is likely to be mediated, at least in part, by the activation of mitochondrial BK channels.

Vasorelaxation by hydrogen sulphide involves activation of Kv7 potassium channels

Hydrogen sulphide (H2S) has been recently hypothesized to be an endogenous adipocyte-derived relaxing factor, evoking vasorelaxation of conductance and resistance vessels. Although the activation of ATP-sensitive potassium channels is known to play a central role in H2S-induced vasorelaxation, activation of vascular Kv7 voltage-gated potassium channels has also been suggested. To investigate this possibility, the ability of selective activators and blockers of distinct classes of potassium channels to affect vasodilation induced by the H2S-donor NaHS, as well as NaHS-induced Rb(+) efflux in endothelium-denuded rat aortic rings, was investigated. NaHS-induced changes of membrane potential were fluorimetrically assessed on human vascular smooth muscle (VSM) cells. Modulation of Kv7.4 channels by NaHS was assessed by electrophysiological studies, upon their heterologous expression in CHO cells. In isolated aortic rings, NaHS evoked vasorelaxing responses associated with an increase of Rb(+)-efflux. NaHS promoted membrane hyperpolarization of human VSM cells. These effects were antagonized by selective blockers of Kv7 channels. The H2S-donor caused a left-shift of current activation threshold of Kv7.4 channels expressed in CHO cells. Altogether, these results suggest that the activation of Kv7.4 channels is a key mechanism in the vascular effects of H2S. Given the relevant roles played by Kv7.4 channels in VSM contractility and by H2S in circulatory homeostasis regulation, these findings provide interesting insights to improve our understanding of H2S pathophysiology and to focus on Kv7.4 channels as novel targets for therapeutic approaches via the "H2S-system".

Cardioprotective effects of different flavonoids against myocardial ischaemia/reperfusion injury in Langendorff-perfused rat hearts

OBJECTIVE

Flavonoids are important components of 'functional foods', with beneficial effects on the cardiovascular function, mainly due to their antioxidant activity. Many flavonoids exert antihypertensive, anti-atherosclerotic and antiplatelet activity and positive effects against endothelial dysfunction. Recent evidence indicates that they exert cardioprotective effects against myocardial ischaemia/reperfusion (I/R) injury. The aim of this work was to investigate these properties for flavonoids with different structural characteristics.

METHODS

In this work, the cardioprotective effects of eight flavonoids endowed with different structural characteristics were tested on Langendorff-perfused rat hearts submitted to 30 min of global ischaemia followed by 120 min of reperfusion (I/R).

KEY FINDINGS

Only the 5-hydroxy-substituted derivatives, such as 5-hydroxy flavone, apigenin, chrysin and naringenin, conferred on the hearts an improved post-ischaemic functional recovery associated with lower extension of tissue injury. A similar pharmacological profile was exhibited by 5-methoxy flavone. In contrast, 6-hydroxy flavone, 7-hydroxy flavone and 4'-hydroxy flavanone did not confer significant protection against the injury induced by I/R.

CONCLUSIONS

Some flavonoids exhibit direct cardioprotective effects against the injury induced by drastic I/R and this pharmacological property seems to be related to their structural characteristics. Such an influence of structural requirements seems to indicate that the cardioprotective effects may be due to the interaction with specific pharmacological targets.

Hydrogen sulphide: biopharmacological roles in the cardiovascular system and pharmaceutical perspectives

Hydrogen sulphide (H(2)S) is now viewed as an important endogenous gasotransmitter, which exhibits many beneficial effects on the cardiovascular system. H(2)S is biosynthesized in mammalian tissues by both non-enzymatic processes and several enzymatic pathways ensured by cystathionine-β-synthase and cystathionine-γ-lyase. H(2)S is endowed with the antioxidant properties of inorganic and organic sulphites, being a scavenger of reactive oxygen species. Furthermore, H(2)S triggers other important effects and the activation of ATP-sensitive potassium channels (KATP) accounts for its vasorelaxing and cardioprotective effects. H(2)S also inhibits smooth muscle proliferation and platelet aggregation. Conversely, the impairment of H(2)S contributes to the pathogenesis of hypertension and is involved in cardiovascular complications associated with diabetes mellitus. There is also evidence of a link between H(2)S and endothelial nitric oxide (NO). Recent observations indicate a possible pathogenic link between deficiencies of H(2)S activity and the progress of endothelial dysfunction. These biological aspects of endogenous H(2)S led to consider this mediator as "the new NO" and to evaluate new attractive opportunities to develop innovative classes of drugs. In this review, the main roles played by H(2)S in the cardiovascular system and the first examples of H(2)S-donor drugs are discussed. Some hybrid drugs are also addressed in this review. In such compounds opportune H(2)S-releasing moieties are conjugated to well-known drugs to improve their pharmacodynamic profile or to reduce the potential for adverse effects.

Role of NF-kappaB and PPAR-gamma in lung inflammation induced by monocyte-derived microparticles

Microparticles (MP) are phospholipid vesicles shed by cells upon activation or apoptosis. Monocyte-derived MP upregulate the synthesis of proinflammatory mediators by lung epithelial cells; the molecular bases of such activity are unknown. Peroxisome proliferator-activated receptors (PPAR) have been demonstrated to be involved in the modulation of nuclear factor (NF)-κB transcriptional activity and inflammation. We investigated whether the upregulation of the synthesis of proinflammatory cytokines by human lung epithelial cells induced by monocyte/macrophage-derived MP involves NF-κB activation and is modulated by PPAR-γ. MP were generated by stimulation of human monocytes/macrophages with the calcium ionophore, A23187. MP were incubated with human lung epithelial cells. NF-κB translocation was assessed by electrophoretic mobility shift assay. Interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1 synthesis was assessed by ELISA and RT-PCR. Stimulation of A549 alveolar cells with monocyte/macrophage-derived MP caused an increase in NF-κB activation and IL-8 and MCP-1 synthesis that was inhibited by pre-incubation with the PPAR-γ agonists, rosiglitazone and 15-deoxy-Δ12,14-prostaglandin-J2. Parallel experiments with normal human bronchial epithelial cells largely confirmed the results. The effects of PPAR-γ agonists were reversed by the specific antagonist, GW9662. Upregulation of the synthesis of proinflammatory mediators by human lung epithelial cells induced by monocyte/macrophage-derived MP is mediated by NF-κB activation through a PPAR-γ dependent pathway.

Anti-ischaemic activity of an antioxidant aldose reductase inhibitor on diabetic and non-diabetic rat hearts

Objectives

Many observations report the cardioprotective effects of inhibitors of aldose reductase in different models of ischaemia–reperfusion injury in diabetic myocardium. In this paper, the inhibitory effects of the new pyrido[1,2-a]-pyrimidin-4-one derivative PPO, whose aldose reductase-inhibitory and antioxidant effects were shown in a previous study, were evaluated.

Methods

The effect of PPO was evaluated on aldose reductase from hearts of diabetic and non-diabetic rats, and compared with that of the reference drug epalrestat. Moreover, the two drugs were tested on isolated and Langendorff-perfused diabetic and non-diabetic hearts submitted to ischaemia–reperfusion cycle.

Key findings

Epalrestat showed equivalent levels of potency in inhibiting the activity of the enzyme in the diabetic and in the non-diabetic hearts. On the contrary, the inhibitory potency of PPO was decreased in the diabetic organs. In the diabetic hearts submitted to ischaemia–reperfusion, an increased level of heart aldose reductase activity was recorded, and both PPO and epalrestat produced cardioprotective effects, suggesting that aldose reductase is deeply involved in the process of ischaemia–reperfusion injury in diabetic myocardium. In non-diabetic hearts, where aldose reductase has a lower activity, epalrestat failed to produce significant protection, while PPO still maintained cardioprotective effects, which may be reasonably attributed to useful ‘ancillary’ effects – such as antioxidant activity – independent from the aldose reductase inhibition.

Conclusions

Therefore PPO, a new molecule endowed with both aldose reductase-inhibitory effects and antioxidant activity, may represent the prototype of a new class of multitarget drugs, focused on two different steps deeply involved in the pathogenesis of ischaemic injury of diabetic hearts.

Synthesis, characterization and evaluation of thiolated quaternary ammonium-chitosan conjugates for enhanced intestinal drug permeation

In a previous report quaternary ammonium-chitosan conjugates (N(+)-Chs) endowed with intestinal drug permeability-enhancing properties were described. They are characterized by short pendant chains of n adjacent diethyl-dimethylene-ammonium groups substituted onto the primary amino group of the chitosan (Ch) repeating units. In the present work two N(+)-Chs, one having DS (degree of substitution)=59.2+/-4.5%, n=1.7+/-0.1 (N(+)(60)-Ch), the other one having DS=40.6+/-1.3%, n=3.0+/-0.2 (N(+)(40)-Ch) were used to synthesize novel multifunctional non-cytotoxic Ch derivatives, each carrying thiol along with quaternary ammonium groups (N(+)-Ch-SH), with increased potential to enhance transepithelial drug transport. They have been obtained by transforming the residual free amino groups of N(+)(60)-Ch and N(+)(40)-Ch into 3-mercaptopropionamide moieties. The former yielded 4.5+/-0.7% thiol-bearing groups, the latter, 5.2+/-1.1% of such groups, on a Ch repeating unit basis. The multifunctional derivatives have improved the ability of the parent N(+)-Chs to enhance the permeability of the water-soluble macromolecular fluorescein isothiocyanate dextran, MW 4400 Da (FD4) and that of the lipophilic dexamethasone (DMS) across the excised rat intestinal mucosa and Caco-2 cell monolayer, respectively. The data from the present work altogether point to a synergism of quaternary ammonium and thiol groups to improve the intestinal drug absorption enhancing properties of the multifunctional Ch derivatives.

Total plasma homocysteine correlates in women with gestational diabetes

AIM

We aim to assess serum total homocysteine (tHcy) associations with metabolic syndrome components and B-vitamins in women with gestational diabetes mellitus (GDM).

METHODS

We studied 61 consecutive pregnant women, 44 with GDM and 17 with normal glucose tolerance (CG). Serum homocysteine levels were analyzed by ELISA, using Bio-Rad reagents. Serum folates and vitamin B(12) concentrations were determined by chemiluminescent immunoassay, free fatty acids (FFA) and lipids enzymatically.

RESULTS

Serum homocysteine levels were similar in both the GDM and the CG groups (8+/-2.0 vs 7.4+/-1.1 micromol/l, respectively). Women with GDM in comparison to CG women were characterized by higher values of homeostasis model of insulin resistance (HOMA-IR) (2.8+/-1.7 vs 1.6+/-0.9, P<0.01), serum triglycerides (2.7+/-0.9 vs 1.9+/-0.5 mmol/l, P<0.01) and FFA (0.6+/-0.2 vs 0.46+/-0.2 mmol/l, P<0.05). In GDM women serum tHcy correlated with vitamin B(12) (r= -0.47, P<0.01) and folates (r= -0.51, P<0.001); in CG women with HOMA-IR, a marker of insulin resistance (r= -0.49, P<0.05). In multiple regression analysis with serum tHcy as a dependent variable, folate and vitamin B(12) entered the analysis in GDM women (beta= -0.42 and -0.34, respectively, P<0.05), whereas in CG cystatin C and HOMA-IR entered the analysis (P<0.05).

CONCLUSIONS

In women with GDM, serum homocysteine is significantly associated with vitamin B(12) and folate levels, while in healthy pregnant women with HOMA-IR and with kidney function. The results suggest the importance of the B-group vitamins in regulation of serum tHcy levels in women with insulin resistance/gestational diabetes, what might be relevant in protection against pregnancy complications associated with elevated tHcy in GDM women.