Biomedical subjects

Antonella Liantonio

Publications and source records attributed to Antonella Liantonio.

17 recordsLinked to original sources

PubMed2005

Activation and inhibition of kidney CLC-K chloride channels by fenamates.

CLC-K Cl(-) channels are selectively expressed in kidney and ear, where they are pivotal for salt homeostasis, and loss-of-function mutations of CLC-Kb produce Bartter's syndrome type III. The only ligand known for CLC-K channels is a derivative of the 2-p-chlorophenoxypropionic acid (CPP), 3-phenyl-CPP, which blocks CLC-Ka, but not CLC-Kb. Here we show that in addition to this blocking site, CLC-K channels bear an activating binding site that controls channel opening. Using the voltage-clamp technique on channels expressed in Xenopus laevis oocytes, we found that niflumic acid (NFA) increases CLC-Ka and CLC-Kb currents in the 10 to 1000 microM range. Flufenamic acid (FFA) derivatives or high doses of NFA produced instead an inhibitory effect on CLC-Ka, but not on CLC-Kb, and on blocker-insensitive CLC-Ka mutants, indicating that the activating binding site is distinct from the blocker site. Evaluation of the sensitivity of CLC-Ka to derivatives of NFA and FFA together with a modeling study of these ligands allow us to conclude that one major characteristic of activating compounds is the coplanarity of the two rings of the molecules, whereas block requires a noncoplanar configuration. These molecules provide a starting point for identification of diuretics or drugs useful in the treatment of Bartter's syndrome.

Animals↗

PubMed2005

Fiber type-related changes in rat skeletal muscle calcium homeostasis during aging and restoration by growth hormone.

The mechanisms by which aging induces muscle impairment are not well understood yet. We studied the impact of aging on Ca2+ homeostasis in the slow-twitch soleus and the fast-twitch extensor digitorum longus (EDL) muscles of aged rats by using the fura-2 fluorescent probe. In both muscles aging increases the resting cytosolic calcium concentration ([Ca2+]i). This effect was independent on calcium influx since a reduced resting permeability of sarcolemma to divalent cations was observed in aged muscles likely due to a reduced activity of leak channels. Importantly the effects of aging on resting [Ca2+]i, fiber diameter, mechanical threshold and sarcolemmal resting conductances were less pronounced in the soleus muscle, suggesting that muscle impairment may be less dependent on [Ca2+]i in the slow-twitch muscle. The treatment of aged rats with growth hormone restored the resting [Ca2+]i toward adult values in both muscles. Thus, an increase of resting [Ca2+]i may contribute to muscle weakness associated with aging and may be considered for developing new therapeutic strategies in the elderly.

Aging↗

PubMed2005

Recovery of the soleus muscle after short- and long-term disuse induced by hindlimb unloading: effects on the electrical properties and myosin heavy chain profile.

The hindlimb unloading (HU) rat is a model of muscle disuse characterized by atrophy and slow-to-fast phenotype transition of the postural muscles, such as the soleus. We previously found that the resting sarcolemmal chloride conductance (gCl) that is typically lower in slow-twitch myofibers than in fast ones increased in soleus fibers following 1 to 3 weeks of HU in accord with the slow-to-fast transition of myosin heavy chain (MHC) isoforms. Nevertheless, the gCl already raised after a 3-day HU, whereas no change in MHC expression was detected. The present work evaluates the ability of soleus muscle to recover on return to normal load after a short (3 days) or long (2 weeks) disuse period. The changes observed after a 2-week HU were slowly reversible, since 3-4 weeks of reloading were needed to completely recover gCl, fiber diameter, MHC expression pattern, as well as the mechanical threshold Rheobase, an index of calcium homeostasis. After 3-day HU, the gCl increased homogeneously in most of the soleus muscle fibers and gCl recovery was rapidly completed after 4-day reloading. These results suggest different induction mechanisms for gCl augmentation after the short and long HU periods, as well as a possible role for gCl in the slow muscle adaptation to disuse.

Adaptation, Physiological↗

PubMed2005

A multidisciplinary evaluation of the effectiveness of cyclosporine a in dystrophic mdx mice.

Chronic inflammation is a secondary reaction of Duchenne muscular dystrophy and may contribute to disease progression. To examine whether immunosuppressant therapies could benefit dystrophic patients, we analyzed the effects of cyclosporine A (CsA) on a dystrophic mouse model. Mdx mice were treated with 10 mg/kg of CsA for 4 to 8 weeks throughout a period of exercise on treadmill, a protocol that worsens the dystrophic condition. The CsA treatment fully prevented the 60% drop of forelimb strength induced by exercise. A significant amelioration (P < 0.05) was observed in histological profile of CsA-treated gastrocnemius muscle with reductions of nonmuscle area (20%), centronucleated fibers (12%), and degenerating area (50%) compared to untreated exercised mdx mice. Consequently, the percentage of normal fibers increased from 26 to 35% in CsA-treated mice. Decreases in creatine kinase and markers of fibrosis were also observed. By electrophysiological recordings ex vivo, we found that CsA counteracted the decrease in chloride conductance (gCl), a functional index of degeneration in diaphragm and extensor digitorum longus muscle fibers. However, electrophysiology and fura-2 calcium imaging did not show any amelioration of calcium homeostasis in extensor digitorum longus muscle fibers. No significant effect was observed on utrophin levels in diaphragm muscle. Our data show that the CsA treatment significantly normalized many functional, histological, and biochemical endpoints by acting on events that are independent or downstream of calcium homeostasis. The beneficial effect of CsA may involve different targets, reinforcing the usefulness of immunosuppressant drugs in muscular dystrophy.

Animals↗

PubMed2004

Molecular determinants of differential pore blocking of kidney CLC-K chloride channels.

The highly homologous Cl(-) channels CLC-Ka and CLC-Kb are important for water and salt conservation in the kidney and for the production of endolymph in the inner ear. Mutations in CLC-Kb lead to Bartter's syndrome and mutations in the small CLC-K subunit barttin lead to Bartter's syndrome and deafness. Here we show that CLC-Ka is blocked by the recently identified blocker 2-(p-chlorophenoxy)-3-phenylpropionic acid of the rat channel CLC-K1 with an apparent K(D) approximately 80 microM. We also found that DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid), a generic Cl(-) channel blocker, inhibits CLC-Ka (K(D) approximately 90 microM). Surprisingly, the highly homologous channel CLC-Kb is fivefold to sixfold less sensitive to both compounds. Guided by the crystal structure of bacterial CLC proteins, we identify two amino acids, N68/D68 and G72/E72, in CLC-Ka and CLC-Kb, respectively, that are responsible for the differential drug sensitivity. Both residues expose their side chains in the extracellular pore mouth, delineating the probable drug binding site. These novel CLC-K channel blockers are promising lead compounds for the development of new diuretic drugs.

2-Methyl-4-chlorophenoxyacetic Acid↗

PubMed2004

The alteration of calcium homeostasis in adult dystrophic mdx muscle fibers is worsened by a chronic exercise in vivo.

Chronic exercise in vivo aggravates dystrophy in mdx mice. Calcium homeostasis was evaluated ex vivo by micro-spectrofluorometry on tendon-to-tendon dissected extensor digitorum longus (EDL) muscle fibers. Resting cytosolic calcium ([Ca2+]i) and sarcolemmal permeability through Gd3+ -sensitive mechanosensitive calcium (MsCa) channel were significantly higher in mdx vs. wild-type fibers. The exercise further enhanced [Ca2+]i in mdx fibers and increased sarcolemmal permeability by activating nifedipine-sensitive leak calcium channels. The two genotypes did not differ in caffeine sensitivity and in the excitation-calcium release (ECaR) coupling mechanism by K+ depolarization. The exercise produced a similar adaptation of activation curve of ECaR and of sensitivity to caffeine. However, the inactivation of ECaR of mdx fibers did not adapt to exercise. No fiber phenotype transition occurred in exercised muscle. We provide the first evidence that an in vivo exercise worsens the impaired calcium homeostasis of dystrophic fibers, supporting the role of enhanced calcium entrance in dystrophic progression.

Animals↗

PubMed2004

New potent mexiletine and tocainide analogues evaluated in vivo and in vitro as antimyotonic agents on the myotonic ADR mouse.

The antimyotonic activity of chiral derivatives of mexiletine and tocainide, selected as potent use-dependent blockers of skeletal muscle sodium channels, was evaluated in vivo acutely in myotonic ADR mice. The compounds had either aromatic (Me4 and Me6) or branched isopropyl groups (Me5 and To1) on the asymmetric centre, or had this latter one methylene apart from the amino group (Me2). Therapeutic doses of mexiletine (5-10 mg/kg) and tocainide (7-20 mg/kg) significantly reduced the long time of righting reflex (TRR), typical of ADR mice. Me4, Me5 and Me6 were 2-fold more potent than mexiletine. To1 fully normalised the TRR at 7 mg/kg. The electromyographic analysis confirmed a muscle-based activity for drug effectiveness on TRR. All the compounds reduced the myotonic hyperexcitability of intercostal muscle fibres when tested in vitro by current-clamp recordings, with a potency correlated with their action on sodium channels. On stimulus-evoked firing, the isopropyl analogues were 2-4-fold more potent than parent compounds, while the aromatic analogues were about 10-fold more potent than mexiletine. Patch-clamp recordings confirmed a normal-like pharmacological sensitivity of sodium channels of native ADR muscle fibres. Finally, the in vivo antimyotonic activity is due to the block of sodium channels and divergences with in vitro potency can be related to structure-based changes in drug pharmacokinetics.

Action Potentials↗

PubMed2004

Taurine and skeletal muscle disorders.

Taurine is abundantly present in skeletal muscle. We give evidence that this amino acid exerts both short-term and long-term actions in the control of ion channel function and calcium homeostasis in striated fibers. Short-term actions can be estimated as the ability of this amino acid to acutely modulate both ion channel gating and the function of the structures involved in calcium handling. Long-term effects can be disclosed in situations of tissue taurine depletion and are likely related to the ability of the intracellular taurine to control transducing pathways as well as homeostatic and osmotic equilibrium in the tissue. The two activities are strictly linked because the intracellular level of taurine modulates the sensitivity of skeletal muscle to the exogenous application of taurine. Myopathies in which ion channels are directly or indirectly involved, as well as inherited or acquired pathologies characterized by metabolic alterations and change in calcium homeostasis, are often correlated with change in muscle taurine concentration and consequently with an enhanced therapeutic activity of this amino acid. We discuss both in vivo and in vitro evidence that taurine, through its ability to control sarcolemmal excitability and muscle contractility, can prove beneficial effects in many muscle dysfunctions.

Aging↗

PubMed2004

Investigations of pharmacologic properties of the renal CLC-K1 chloride channel co-expressed with barttin by the use of 2-(p-Chlorophenoxy)propionic acid derivatives and other structurally unrelated chloride channels blockers.

CLC-K chloride channels are expressed in the kidney, where they play a pivotal role in the mechanisms of urine concentration and Na(+) reabsorption. The identification of barttin as an essential beta-subunit of CLC-K channels allowed performance of a pharmacologic characterization of wild-type CLC-K1 expressed in Xenopus oocytes. To this end, a series of 2-(p-chlorophenoxy)propionic acid (CPP) derivatives were screened using the two-microelectrode voltage-clamp technique. Several chemical modifications regarding the phenoxy group of the side chain (elimination of the oxygen atom or of methylenic groups, substitutions of the chlorine atom) did not alter the drug blocking activity, with five different derivatives showing a similar potency. Among these, a derivative of CPP carrying a benzyl group on the chiral center in the place of the methyl group represented the minimal structure for blocking CLC-K1. It inhibited the channel from the extracellular side with an affinity in the 150 micro M range. The blocking potency of this compound is fourfold increased by lowering the extracellular chloride concentration, suggesting that the drug interacts with the channel pore. Concomitantly, the effect of some "classical" Cl(-) channel blockers (9-anthracenecarboxylic acid, 2-(phenylamino)benzoic acid, iminodibenzoic acid, niflumic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid, 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid disodium salt, and 4-acetamido-4'-isothiocyanato-2,2'-stilbenedisulfonic acid disodium salt) was screened. 4,4'-Diisothiocyanato-2,2'-stilbenedisulfonic acid disodium salt was the only one capable of blocking CLC-K1 with a potency similar to the CPP derivative, although in an irreversible manner. The newly identified substances provide a useful tool to investigate the biophysical and physiologic role of these renal channels and a starting point for the development of therapeutic drugs with diuretic action.

2-Methyl-4-chlorophenoxyacetic Acid↗

PubMed2003

Decrease in resting calcium and calcium entry associated with slow-to-fast transition in unloaded rat soleus muscle.

Using fura-2 and the manganese quenching technique, we show here that sarcolemmal permeability to cations (SP-Ca) of slow-twitch muscles is greater than that of fast-twitch ones. This appears to be related to a higher expression and/or activity of stretch-activated channels, whereas leak channel activities are similar. During hindlimb suspension (HU), we found highly correlated decreases in SPCa and resting calcium of soleus muscle toward values of extensor digitorum longus (EDL) muscle. This was significant as soon as 3 days of suspension, contrary to soleus muscle caffeine sensitivity and responsiveness that were not modified after this HU period. After 14 days of HU, SP-Ca, resting calcium, and caffeine response of soleus muscle became similar to that normally observed in EDL muscle. These results demonstrate that the correlated decreases in SP-Ca and resting calcium precede most functional changes due to HU. Given the known shortening of HU soleus muscle, we proposed that this could induce a decrease of SP-Ca and a consequent reduction of resting calcium. According to the crucial role of resting cytosolic free calcium in the maintenance and the adaptation of muscle phenotype, our results suggest that slow-to-fast transition of HU soleus muscle is calcium dependent.

Animals↗

PubMed2003

Growth hormone secretagogues modulate the electrical and contractile properties of rat skeletal muscle through a ghrelin-specific receptor.

(1) Growth hormone secretagogues (GHS) exhibit potent growth hormone (GH)-releasing activity through the activation of a pituitary receptor. Here, we consider the possibility that GHS can target a specific receptor in rat skeletal muscle and have a role in the control of muscle function. (2) By means of the intracellular microelectrode technique, we found that in vitro application of hexarelin and L-163,255 dose dependently reduced resting chloride (gCl) and potassium (gK) conductances in rat skeletal muscle. These effects were prevented by the GHS-receptor antagonist [D-Lys-3]-GHRP-6, and by either phospholipase C or protein kinase C (PKC) inhibitors. Ghrelin, a natural ligand of GHS receptors, also induced a reduction of muscle gCl and gK, which was antagonised by [D-Lys-3]-GHRP-6. (3) Both GHS shifted the mechanical threshold for the contraction of muscle fibres towards more negative voltages. Accordingly, by means of FURA-2 fluorescent measurements, we demonstrated that L-163,255 induced a resting [Ca(2+)](i) increase, which was reversible and not blocked by nifedipine or removal of external Ca(2+). (4) Ageing is a condition characterised by a deficit of GH secretion, which in turn modifies the electrical and contractile properties of skeletal muscle. In contrast to GH, chronic treatment of aged rats with hexarelin or L-163,255 failed to restore the electrical and contractile muscle properties. Moreover, the two GHS applied in vitro were able to antagonise the beneficial effect on gCl and gK obtained through chronic treatment of aged animals with GH. (5) Thus, skeletal muscle expresses a specific GHS receptor able to decrease gCl and gK through a PKC-mediated intracellular pathway. This peripheral action may account for the lack of restoration of skeletal muscle function in long-term GHS-treated aged animals.

Aging↗

PubMed2003

Structural requisites of 2-(p-chlorophenoxy)propionic acid analogues for activity on native rat skeletal muscle chloride conductance and on heterologously expressed CLC-1.

(1) The 2-(p-chlorophenoxy)propionic acid (CPP) modulates in a stereoselective manner the macroscopic chloride conductance (gCl), the electrical parameter sustained by the CLC-1 channel, of skeletal muscle. In order to determine the structural requirements for modulating native gCl and to identify high-affinity ligands, the effects of newly synthesised CPP analogues have been evaluated on gCl of rat EDL muscle fibres by means of the two-microelectrode current-clamp technique. (2) Each type of the following independent modification of CPP structure led to a three- to 10-fold decrease or to a complete lack of gCl-blocking activity: replacement of the electron-attractive chlorine atom of the aromatic ring, substitution of the oxygen atom of the phenoxy group, modification at the chiral centre and substitution of the carboxylic function with a phosphonate one. (3) The analogues bearing a second chlorophenoxy group on the asymmetric carbon atom showed a significant gCl-blocking activity. Similar to racemate CPP, the analogue with this group, spaced by an alkyl chain formed by three methylenic groups, blocked gCl by 45% at 100 micro M. (4) These latter derivatives were tested on heterelogously expressed CLC-1 performing inside-out patch-clamp recordings to further define how interaction between drug and channel protein could take place. Depending on the exact chemical nature of modification, these derivatives strongly blocked CLC-1 with K(D) values at -140 mV ranging from about 4 to 180 micro M. (5) In conclusion, we identified four molecular determinants pivotal for the interaction with the binding site on muscle CLC-1 channels: (a) the carboxylic group that confers the optimal acidity and the negative charge; (b) the chlorophenoxy moiety that might interact with a hydrophobic pocket; (c) the chiral centre that allows the proper spatial disposition of the molecule; (d) an additional phenoxy group that remarkably stabilises the binding by interacting with a second hydrophobic pocket.

2-Methyl-4-chlorophenoxyacetic Acid↗

PubMed2003

Enhanced dystrophic progression in mdx mice by exercise and beneficial effects of taurine and insulin-like growth factor-1.

A preclinical screening for prompt-to-use drugs that are safer than steroids and beneficial in Duchenne muscular dystrophy was performed. Compounds able to reduce calcium-induced degeneration (taurine or creatine 10% in chow) or to stimulate regeneration [insulin-like growth factor-1 (IGF-1); 50 or 500 microg/kg s.c.] were administered for 4 to 8 weeks to mdx mice undergoing chronic exercise on a treadmill, a protocol to worsen dystrophy progression. alpha-Methyl-prednisolone (PDN; 1 mg/kg) was used as positive control. The effects were evaluated in vivo on forelimb strength and in vitro electrophysiologically on the macroscopic chloride conductance (gCl), an index of degeneration-regeneration events in mdx muscles, and on the mechanical threshold, a calcium-sensitive index of excitation-contraction coupling. The exercise produced a significant weakness and an impairment of gCl, by further decreasing the already low value of degenerating diaphragm (DIA) and fully hampering the increase of gCl typical of regenerating extensor digitorum longus (EDL) mdx muscle. The already negative voltage threshold for contraction of mdx EDL was also slightly worsened. Taurine > creatine > IGF-1 counteracted the exercise-induced weakness. The amelioration of gCl was drug- and muscle-specific: taurine was effective in EDL, but not in DIA muscle; IGF-1 and PDN were fully restorative in both muscles, whereas creatine was ineffective. An acute effect of IGF-1 on gCl was observed in vitro in untreated, but not in IGF-1-treated exercised mdx muscles. Taurine > PDN > IGF-1, but not creatine, significantly ameliorated the negative threshold voltage values of the EDL fibers. The results predict a potential benefit of taurine and IGF-1 for treating human dystrophy.

Animals↗

PubMed2002

Pre-clinical trials in Duchenne dystrophy: what animal models can tell us about potential drug effectiveness.

The symptomatic pharmacological therapy of Duchenne dystrophy is poor, glucocorticoids being the sole compounds showing a certain efficacy, although their use is restricted by serious side effects. Pre-clinical trials of prompt-to-use drugs need reliable animal models of the human disease to predict drug effectiveness in patients. The exercised mdx mouse develops a typical pattern of muscle weakness in vivo, which has already been used as an index on which to evaluate drug effectiveness. We have demonstrated that the macroscopic conductance to chloride ion, an index of degeneration-regeneration events occurring in mdx mouse muscles, is specifically impaired by a chronic exercise protocol and is sensitive to the action of in vivo administered drugs acting either by stimulating regeneration (insulin-like growth factor-1 and steroids) or by counteracting calcium-induced degeneration or inflammation (Taurine and steroids). The monitoring of conductance to chloride ion also allows the evaluation of false positive compounds, effective on mouse strength in vivo but not at muscle level, and the functional correlation with other cellular parameters.

Adrenal Cortex Hormones↗

PubMed2002

Change of chloride ion channel conductance is an early event of slow-to-fast fibre type transition during unloading-induced muscle disuse.

Disuse of postural slow-twitch muscles, as it occurs in hypogravity, induces a slow-to-fast myofibre type transition. Nothing is known about the effects of weightlessness on the resting membrane chloride conductance (gCl), which controls sarcolemma excitability and influences fibre type transition during development and adult life. Using the current-clamp method, we observed that rat hindlimb unloading (HU) for 1-3 weeks increased gCl in fibres of the slow-twitch soleus (Sol) muscle toward values found in fast muscle. Northern blot analysis suggested that this effect resulted from an increased ClC-1 chloride channel mRNA level. In the meantime, a 4-fold increase in fibres expressing fast isoforms of the myosin heavy chain (MHC) was observed by immunostaining of muscle sections. Also, Sol muscle function evolved toward a fast phenotype during HU, as demonstrated by the positive shift of the threshold potential for contraction. After 3-days HU, Sol muscle immunostaining and RT-PCR experiments revealed no change in MHC protein and mRNA expression, whereas the gCl was already maximally increased, due to a pharmacologically probed, increased activity of ClC-1 channels. Thus the increase in gCl is an early event in Sol muscle experiencing unloading, suggesting that gCl may play a role in muscle adaptation to modified use. Pharmacological modulation of ClC-1 channels may help to prevent disuse-induced muscle impairment.

Animals↗

PubMed2002

Molecular requisites for drug binding to muscle CLC-1 and renal CLC-K channel revealed by the use of phenoxy-alkyl derivatives of 2-(p-chlorophenoxy)propionic acid.

CLC channels are a gene family of Cl(-) channels that serve a variety of functions, several of which are involved in genetic diseases. Few specific ligands of CLC channels are known that could be useful as pharmacological tools or potential drugs. We synthesized various derivatives of 2-(p-chlorophenoxy)propionic acid, the S(-)-enantiomer of which is a specific blocker of the muscle channel CLC-1. In particular, compounds with different alkyl or phenoxy-alkyl groups on the chiral center, isosteres of the oxygen in the aryloxy moiety, or bioisosteres of the carboxy function were prepared. We found that compounds containing a phenoxy and a phenoxy-alkyl group on the chiral center (bis-phenoxy derivatives) specifically inhibited renal CLC-K channels from the extracellular side with an affinity in the 150-microM range and with almost no effect on other CLC channels when applied from the outside. Surprisingly, the same substances inhibited CLC-1 from the intracellular side in a voltage-dependent manner with an apparent K(D) of <5 microM at -140 mV, thus being the most potent blockers of a CLC channel known so far. Although the chlorine atom in para- position of the second phenoxy group was essential for inhibition of CLC-K channels from the outside, it could be substituted by a methoxy group without changing the potency of block for CLC-1 from the inside. These newly identified substances provide powerful tools for studying the structure-function relationship and the physiological role of CLC channels and may represent a starting point for the development of useful drugs targeting CLC-K channels.

2-Methyl-4-chlorophenoxyacetic Acid↗

PubMedDate not supplied

Mechanisms of block of muscle type CLC chloride channels (Review).

CLC proteins are a nine-member gene family of Cl- channels that have diverse roles in the plasma membrane and in intracellular organelles. The recent structure determination of bacterial CLC homologues by Dutzler et al. was a breakthrough for the structure-function analysis of CLC channels. This review describes the mechanisms of inhibition of muscle type CLC channels by two classes of small organic substances: 9-anthracene carboxylic acid (9AC) and p-chlorophenoxy propionic acid (CPP). Both substances block muscle type CLC channels (CLC-0 and CLC-1) from the intracellular side. For CPP, one could show that it inhibits the individual protopores of the double-barrelled channel. A major difference between the two types of blockers is the extremely slow binding- and unbinding-kinetics of 9AC (time scale of min), compared to that of CPP block (time scale of s), while the general mechanism of block seems to be quite similar. In the case of the chiral CPP only the S(-) enantiomer is effective. Both substances exhibit a strongly voltage-dependent block with strong inhibition at negative voltages and relief of block at depolarizing potentials at which the channels tend to open maximally. A quantitative kinetic model was developed for the CPP block of CLC-0 in which the closed state has a much larger affinity for CPP than the open state and opening of drug-bound channels is greatly slowed compared to drug-free channels. First experiments with mutated CLC-0 channels and with derivatives of CPP strongly support the pore localization of the CPP binding site. This work provides the basis for the use of these small organic substances as tools to investigate the pharmacological properties of mammalian CLC channels guided by the crystallographic structure of bacterial CLC homologues. They might also turn out to be useful to obtain information about the intricate coupling of gating and permeation that characterizes CLC channels.

Animals↗