Inhibitory Effects Of Local Anesthetics Research Articles

Inhibitory effects of local anesthetics on muscarinic receptors: effects on the Ca<sup>2+</sup> release from intracellular store and recruitment of beta-arrestin.

Inhibitory effects of local anesthetics on muscarinic receptors: effects on the Ca<sup>2+</sup> release from intracellular store and recruitment of beta-arrestin.

Inhibitory effects of local anesthetics on the proteasome and their biological actions

Local anesthetics (LAs) inhibit endoplasmic reticulum-associated protein degradation, however the mechanisms remain elusive. Here, we show that the clinically used LAs pilsicainide and lidocaine bind directly to the 20S proteasome and inhibit its activity. Molecular dynamic calculation indicated that these LAs were bound to the β5 subunit of the 20S proteasome, and not to the other active subunits, β1 and β2. Consistently, pilsicainide inhibited only chymotrypsin-like activity, whereas it did not inhibit the caspase-like and trypsin-like activities. In addition, we confirmed that the aromatic ring of these LAs was critical for inhibiting the proteasome. These LAs stabilized p53 and suppressed proliferation of p53-positive but not of p53-negative cancer cells.

The Inhibitory Effects of Local Anesthetics on Primary Sensory Nerve and Parasympathetic Nerve in Rabbit Eye

Primary sensory nerves transmit information to both the periphery and central nervous systems, and they mediate neurogenic inflammation by release of neurotransmitters, such as tachykinins, in the periphery. Because the effect of local anesthetics on neurogenic inflammation is a subject of controversy, we investigated the direct effect of local anesthetics on tachykininergic neurotransmission, comparing it with cholinergic neurotransmission in the rabbit iris sphincter muscle. Rabbit iris sphincter muscle is innervated by trigeminal tachykininergic and parasympathetic cholinergic nerves, and the electrical transmural stimulation produces tachykininergic and cholinergic contractions. Cocaine and lidocaine (1-300 microM) attenuated tachykininergic and cholinergic contractions induced by electrical transmural stimulation in concentration- and stimulus frequency-dependent manner. However, the sensitivity to both local anesthetics was slightly, but significantly, higher in tachykininergic than in cholinergic responses. Exogenous neurokinin A and carbachol produced contractions that were not inhibited by 100 microM of cocaine and lidocaine. These results show that local anesthetics have a direct inhibitory effect on tachykininergic neurotransmission of the trigeminal sensory nerve, and the effect on this nerve is more potent than on the parasympathetic nerve and suggests that local anesthetics may have antineurogenic inflammatory effects via the inhibitory effects on the peripheral transmission of primary sensory nerve.

Molecular mechanisms of the inhibitory effects of bupivacaine, levobupivacaine, and ropivacaine on sarcolemmal adenosine triphosphate-sensitive potassium channels in the cardiovascular system.

Sarcolemmal adenosine triphosphate-sensitive potassium (KATP) channels in the cardiovascular system may be involved in bupivacaine-induced cardiovascular toxicity. The authors investigated the effects of local anesthetics on the activity of reconstituted KATP channels encoded by inwardly rectifying potassium channel (Kir6.0) and sulfonylurea receptor (SUR) subunits. The authors used an inside-out patch clamp configuration to investigate the effects of bupivacaine, levobupivacaine, and ropivacaine on the activity of reconstituted KATP channels expressed in COS-7 cells and containing wild-type, mutant, or chimeric SURs. Bupivacaine inhibited the activities of cardiac KATP channels (IC50 = 52 microm) stereoselectively (levobupivacaine, IC50 = 168 microm; ropivacaine, IC50 = 249 microm). Local anesthetics also inhibited the activities of channels formed by the truncated isoform of Kir6.2 (Kir6.2 delta C36) stereoselectively. Mutations in the cytosolic end of the second transmembrane domain of Kir6.2 markedly decreased both the local anesthetics' affinity and stereoselectivity. The local anesthetics blocked cardiac KATP channels with approximately eightfold higher potency than vascular KATP channels; the potency depended on the SUR subtype. The 42 amino acid residues at the C-terminal tail of SUR2A, but not SUR1 or SUR2B, enhanced the inhibitory effect of bupivacaine on the Kir6.0 subunit. Inhibitory effects of local anesthetics on KATP channels in the cardiovascular system are (1) stereoselective: bupivacaine was more potent than levobupivacaine and ropivacaine; and (2) tissue specific: local anesthetics blocked cardiac KATP channels more potently than vascular KATP channels, via the intracellular pore mouth of the Kir6.0 subunit and the 42 amino acids at the C-terminal tail of the SUR2A subunit, respectively.

The inhibitory effect of local anesthetics on bradykinin-induced phospholipase D activation in rat pheochromocytoma PC12 cells.

Bradykinin induces activation of phospholipase D (PLD) via B(2) receptors in neuronal cells. To demonstrate molecular mechanism(s) of local anesthetics, we examined whether and how local anesthetics affect bradykinin-induced PLD activation in PC12 cells. Using [(3)H]Palmitic acid-labeled PC12 cells stimulated with bradykinin, formation of [(3)H]phosphatidylbutanol was measured as a variable of PLD activity. Bradykinin-stimulated PLD activity seemed to peak at 2 min. Procaine, lidocaine, ropivacaine, bupivacaine, and tetracaine suppressed the bradykinin-induced PLD activation. We chose tetracaine, the most potent drug among the local anesthetics tested, to examine how local anesthetics affect phospholipase C, protein tyrosine kinase, and extracellular signal-regulated kinase, which are the molecules upstream of PLD. Tetracaine at clinically relevant concentrations (1 approximately 10 x 10(-4) M) inhibited the bradykinin-induced PLD activation in a dose- and time-dependent manner, but neither tetrodotoxin nor nifedipine affected the PLD activation. Tetracaine (5 x 10(-4) M) slightly potentiated brady-kinin-induced phospholipase C activation. Bradykinin-stimulated protein tyrosine-phosphorylation and extracellular signal-regulated kinase activation were not affected by tetracaine. Tetracaine significantly decreased PLD activity of membrane fraction in PC12 cells. These results indicate that local anesthetics depress bradykinin-induced lipid signaling pathway(s) and may provide some clues to understanding the molecular mechanisms of these drugs for anesthesia or analgesia. Local anesthetics depressed the bradykinin-induced activation of phospholipase D (PLD) in PC12 cells. The effects of tetracaine, the most potent among the anesthetics tested, on the bradykinin-induced intracellular signaling molecules were examined. The bradykinin-induced PLD activation could be one of the potential intracellular signaling molecular sites of local anesthetic action.

Comparison of inhibitory effects of local anesthetics on immune functions of neutrophils

Immunological effects of a variety of local anesthetics on adhesion, phagocytosis, and the production of superoxide anion and hydrogen peroxide by neutrophils were compared. Neutrophils were isolated by peritoneal lavage from rats, 4 h after injection of 1% glycogen. Lidocaine, mepivacaine, procaine, prilocaine and tetracaine at 1 mg/ml inhibited adhesion, phagocytosis, and the production of superoxide anion and hydrogen peroxide in neutrophils. Moreover, lidocaine, mepivacaine, procaine and prilocaine at 0.1 mg/ml inhibited the production of superoxide anion and hydrogen peroxide but not adhesion or phagocytosis. In contrast, tetracaine at 0.1 mg/ml inhibited phagocytosis, and the production of superoxide anion and hydrogen peroxide but not adhesion. At 0.01 mg/ml, however, tetracaine inhibited the production of superoxide anion and hydrogen peroxide; in contrast, other drugs failed to affect neutrophil function. These results suggest that the local anesthetics may affect adhesion, phagocytosis, and the production of superoxide anion and hydrogen peroxide by neutrophils.

The α and γ subunit-dependent effects of local anesthetics on recombinant GABA A receptors

Although convulsions due to local anesthetic systemic toxicity are thought to be due to inhibition of GABA A receptor-linked currents in the central nervous system, the mechanism of action remains unclear. We therefore examined the effects of local anesthetics on γ-aminobutyric acid (GABA)-induced currents using recombinant GABA A receptors with specific combinations of subunits. Murine GABA A receptors were expressed by injection of cRNAs encoding each subunit into Xenopus oocytes. The effects of local anesthetics (lidocaine, bupivacaine, procaine and tetracaine) on GABA-induced currents of receptors expressing different subunit combinations (α1β2, α1β2γ2s, α4β2γ2s and β2) were examined via the two electrode voltage clamp method. At α1β2, α1β2γ2s and α4β2γ2s GABA A receptors, all local anesthetics inhibited GABA-induced currents in a dose-dependent manner. The presence of the γ2s subunit resulted in a greater inhibition by all local anesthetics, but the presence of the α4 subunit resulted in less inhibition. At β2 homomeric receptors, local anesthetics directly induced an outward current similar to that of picrotoxin. These data indicated that (1) the α and γ subunits of GABA A receptors modulated the inhibitory effects of local anesthetics on GABA A function, and (2) local anesthetics can activate the β2 subunit and may block the GABA A receptor channel pore.

Inhibition of germ tube formation by Candida albicans by local anesthetics: an effect related to ionic channel blockade.

Formation of germ tubes by Candida albicans has been assumed as a putative virulence factor. Local anesthetics (LAs), e.g., lidocaine and bupivacaine, are known to inhibit germ tube formation. The study confirmed this observation for the novel drug ropivacaine, although it was less potent than the former two drugs. Hypothesizing that the effect is due to blockading ionic channels, we exposed Candida albicans to selective calcium blockers, i.e., nifedipine and verapamil, and to a general blocker of ionic channels, i.e., lanthanum. All blockers inhibited germ tube formation. The effect was dose-dependent and pH-independent. Addition of calcium reverted the effect of the blockers as well as the effect of lidocaine and ropivacaine. The study suggests that the inhibitory effect of LAs on germ tube formation by C. albicans is due to blockade of ionic channels, particularly calcium channels. Therefore, LAs can affect morphology and probably also the pathogenesis of C. albicans.

P-553 - Mechanism of inhibitory effects of local anesthetics on agonist-induced intestinal motility

P-553 - Mechanism of inhibitory effects of local anesthetics on agonist-induced intestinal motility

P–590 - Inhibitory effects of local anesthetics on agonist-induced contractions in guinea-pig ileal longitudinal muscle.

P–590 - Inhibitory effects of local anesthetics on agonist-induced contractions in guinea-pig ileal longitudinal muscle.

P-568 - Inhibitory effects of local anesthetics on Ca2+ influx in rat DRG neurons

P-568 - Inhibitory effects of local anesthetics on Ca2+ influx in rat DRG neurons

The inhibitory effects of local anesthetics on superoxide generation of neutrophils correlate with their partition coefficients.

Lidocaine and tetracaine suppress superoxide anion (O2-) generation of neutrophils. We examined the effects of eight local anesthetics on O2- generation in human neutrophils and searched for a potential relationship between the biological activities and the physicochemical properties of presently available eight local anesthetics. Human neutrophils incubated with local anesthetic and a Cypridina luciferin analog as a O2(-)-specific chemiluminescence probe were stimulated by phorbol ester. The chemiluminescence development based on O2- generation was monitored by a luminometer. All of the tested local anesthetics suppressed O2- generation in a concentration-dependent manner. The concentration of each of eight local anesthetics that produced 50% inhibition of peak chemiluminescence (IC50) had a rank order of dibucaine < tetracaine < bupivacaine < ropivacaine < procaine < mepivacaine < lidocaine = prilocaine. A linear relationship was obtained between IC50 values and the values of logarithm of partition coefficient (log P) of eight local anesthetics; log (IC50 in molarity) = -1.252 - 0.514 x log P, r2 = 0.891, P < 0.001. Unlike with staurosporine, which inhibits protein kinase C (PKC), no effect was observed on the O2- generation in the presence of tetrodotoxin (TTX), veratridine (VTD), or amiloride. These results suggest that the inhibitory effects of local anesthetics on O2- generation of neutrophils are predicted by physicochemical properties of the drugs, especially partition coefficients.

The Inhibitory Effects of Local Anesthetics on Superoxide Generation of Neutrophils Correlate with Their Partition Coefficients

Lidocaine and tetracaine suppress superoxide anion (O2 sup -) generation of neutrophils. We examined the effects of eight local anesthetics on O2- generation in human neutrophils and searched for a potential relationship between the biological activities and the physicochemical properties of presently available eight local anesthetics. Human neutrophils incubated with local anesthetic and a Cypridina luciferin analog as a O2--specific chemiluminescence probe were stimulated by phorbol ester. The chemiluminescence development based on O2- generation was monitored by a luminometer. All of the tested local anesthetics suppressed O2- generation in a concentration-dependent manner. The concentration of each of eight local anesthetics that produced 50% inhibition of peak chemiluminescence (IC50) had a rank order of dibucaine < tetracaine < bupivacaine < ropivacaine < procaine < mepivacaine < lidocaine = prilocaine. A linear relationship was obtained between IC50 values and the values of logarithm of partition coefficient (log P) of eight local anesthetics; log (IC50 in molarity) = -1.252 - 0.514 x log P, r2 = 0.891, P < 0.001. Unlike with staurosporine, which inhibits protein kinase C (PKC), no effect was observed on the O2- generation in the presence of tetrodotoxin (TTX), veratridine (VTD), or amiloride. These results suggest that the inhibitory effects of local anesthetics on O2- generation of neutrophils are predicted by physicochemical properties of the drugs, especially partition coefficients. (Anesth Analg 1997;84:405-12)

TMB-8 and dibucaine induce tyrosine phosphorylation and dephosphorylation of a common set of proteins in platelets

Dibucaine and 8-(N,N-diethylamino)octyl 3,4,5-trimethoxybenzoate (TMB-8), which are local anesthetics, affect diverse functions of many cell types. For example, platelet aggregation is inhibited by both, and both cause changes in platelet morphology and structure. Little is known of the mechanisms. We found that both dibucaine (0.125-0.5 mM) and TMB-8 (0.25-1.0 mM) induced rapid tyrosine phosphorylation of several platelet proteins (160, 70-75, and 40 kDa) and dephosphorylation of a 62- to 64-kDa protein detectable by a specific antiphosphotyrosine monoclonal antibody (4G10). Platelet aggregation induced by alpha-thrombin (10 nM) was inhibited by the local anesthetics in approximately the same dose range. Neither dibucaine nor TMB-8 induced activation of protein kinase C (PKC) or myosin light-chain kinase. Their activation was not essential for tyrosine phosphorylation induced by local anesthetics. However, an increase in tyrosine phosphorylation of several proteins (95-130 kDa) induced by alpha-thrombin (10 nM) was inhibited by dibucaine (0.5 mM) or TMB-8 (0.5 mM). Furthermore, when dibucaine (0.5 mM) was added 1 min after addition of alpha-thrombin (10 nM), disaggregation was paralleled to dephosphorylation of many proteins, including those mentioned. Tyrosine phosphorylation and dephosphorylation of specific proteins may account for some of the diverse effects of local anesthetics on platelets and other cells. Addition of TMB-8 (0.5 mM) or dibucaine (0.5 mM) also inhibited activation of PKC, induced by alpha-thrombin (10nM), suggesting that some of the inhibitory effects of dibucaine or TMB-8 may be due to inhibitory effects of local anesthetics on PKC.

Altered stereoselectivity of cocaine and bupivacaine isomers in normal and batrachotoxin-modified Na+ channels.

The inhibitory effects of local anesthetics (LAs) of cocaine and bupivacaine optical isomers on Na+ currents were studied in clonal GH3 cells under whole-cell patch clamp conditions. At holding potential of -100 mV, all four isomers inhibited peak Na+ currents when the cell was stimulated infrequently. The dose-response curves of this tonic block of peak Na+ currents by (-)/(+) cocaine and (-)/(+) bupivacaine were well fitted by the Langmuir isotherm, suggesting that one LA isomer blocked one Na+ channel. Each pair of isomers showed no greater than a twofold difference in stereoselectivity toward Na+ channels. Additional block of Na+ currents occurred when the cell was stimulated at 2 Hz. This use-dependent block was also observed in all four isomers, which again displayed little stereoselectivity. The voltage dependence of the use-dependent block produced by cocaine isomers did not overlap with the activation of Na+ channels but did overlap with the steady-state inactivation (h infinity), indicating that cocaine can bind directly to the inactivated state of Na+ channels before channel opening. In comparison, the peak batrachotoxin (BTX)-modified Na+ currents were little inhibited by cocaine and bupivacaine isomers. However, the maintained BTX-modified Na+ currents were highly sensitive toward the (-) form of cocaine and bupivacaine isomers during a prolonged depolarization. As a result, a profound time-dependent block of BTX-modified Na+ currents was evident in the presence of these LA isomers. The estimated values of the equilibrium dissociation constant (KD in micromolar) at +50 mV were 35.8, 661, 7.0, and 222 for (-)/(+) cocaine and (-)/(+) bupivacaine, respectively. Although chloramine-T (CT) also modified the fast inactivation of Na+ channels and gave rise to a maintained Na+ current during a prolonged depolarization, LA isomers showed no greater stereoselectivity in blocking this maintained current than in blocking the normal transient Na+ current. We conclude that (a) cocaine and bupivacaine isomers exhibit only weak stereoselectivity toward the LA receptor in normal and CT-treated Na+ channels, (b) BTX drastically modifies the configuration of the LA binding site so that the LA stereoselectivity of the open Na+ channels is altered by an order of magnitude, and (c) the (-) forms of cocaine and bupivacaine interact strongly with the open state of BTX-modified Na+ channels but only weakly, if at all, with the closed state. The last finding may explain why most LA drugs were reported to be less effective toward BTX-modified Na+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Lidocaine inhibits prolactin secretion in GH 4C 1 cells by blocking calcium influx

The mechanism of the inhibitory effect of local anesthetics on hormone secretion was studied in the GH 4C 1 line of rat pituitary tumor-derived cells. Lidocaine between 0.1 and 5 mM exerted significant dose-dependent inhibition on the increment in cytosol Ca 2+ concentration ([Ca 2+] i) and prolactin (PRL) secretion induced by 30 mM K +. For both effects the IC 50 was 0.25 mM and maximal inhibition occurred at 5 mM. A normal response returned within 20 min after removal of lidocaine from the incubation medium. 1 μM tetrodotoxin had no effect on the 30 mM K + induced [Ca 2+] i transient or PRL secretion, indicating that Na + channels are not involved in the inhibitory effect of lidocaine. Lidocaine similarly inhibited the [Ca 2+] i increment and PRL secretion induced by 30% medium hyposmolarity and 1 μM Bay K 8644. Lidocaine was much less effective in inhibiting secretion induced by 1 μM phorbol 12-myristate 13-acetate (TPA) or 5 μM forskolin. 5 mM procaine produced effects similar to those of lidocaine. Our data suggest that in GH 4C 1 cells local anesthetics depress secretagogue-induced PRL secretion primarily by blocking Ca + influx, probably through L-type Ca 2+ channels.

Inhibitory effects of local anesthetics on migration, extracellular release of lysosomal enzyme, and superoxide anion production in human polymorphonuclear leukocytes.

This study examined the effects of four typical local anesthetics, lidocaine, prilocaine, procaine and tetracaine, on the functioning of human polymorphonuclear leukocytes (PMN). PMN were stimulated by fMet-Leu-Phe (FMLP) or phorbol myristate acetate (PMA) to elicit chemotaxis, extracellular release of beta-glucuronidase (BGL) and superoxide anion (SOA) production. The four agents inhibited chemotaxis efficiently and in a concentration-dependent manner but had only weak effects on the release of BGL. The effect of tetracaine was strongest, followed by lidocaine, then prilocaine, whereas the effect of procaine was blunt. The 50% inhibitory concentrations (IC50 in molarity) of the four local anesthetics for chemotaxis were as follows: tetracaine = 4.1 x 10(-4), lidocaine = 3.2 x 10(-3), prilocaine = 3.6 x 10(-3), procaine = 4.9 x 10(-3), those for SOA production induced by FMLP were: tetracaine = 3.1 x 10(-4), lidocaine = 5.9 x 10(-3), prilocaine = 1.9 x 10(-2), procaine = 1.2 x 10(-2), those for SOA production induced by PMA were: tetracaine = 1.1 x 10(-3), lidocaine = 1.2 x 10(-2), prilocaine = 1.5 x 10(-2), procaine = 2.5 x 10(-2), and those for release of BGL were: tetracaine = 1.6 x 10(-3), lidocaine = 5.3 x 10(-3), prilocaine = 2.8 x 10(-2), procaine = 1.2 x 10(-1). The IC50 seemed to relate to the anesthetic's chemical structures and their inhibitory properties on PMN functions, as lidocaine and prilocaine, which are aminoamide type anesthetics, preferentially inhibited chemotaxis, whereas tetracaine and procaine, aminoester type anesthetics, inhibited SOA production induced by FMLP. The results suggest that the inhibitory effects of local anesthetics on human PMN functions are also correlated with local anesthetic potency and vary according to differences in their chemical structures.

Inhibitory effect of local anesthetics on Na +/H + antiporter in brush border membrane-reconstituted vesicles

The effects of three local anesthetics, lidocaine, dibucaine, and tetracaine, on Na +/H + antiporter activity were examined in brush border membrane-reconstituted vesicles. Lidocaine at 10 μM inhibited H + efflux in the presence of an inward Na + gradient, suggesting that this anesthetic specifically inhibits the Na +/H + antiporter. On the other hand, dibucaine and tetracaine decreased H + efflux even in the absence of a Na + gradient.

Influence of pH on the inhibitory effects of local anesthetics on histamine release induced from rat mast cells by concanavalin A and compound 48/80.

The study concerned the effects of lidocaine and mepivacaine on rat mast cell histamine release. At low concentrations these drugs inhibited the histamine release induced by concanavalin A and compound 48/80 although, at high concentrations, they caused cell lysis. The mechanism of their inhibition of histamine release was studied by examining the pH dependence of the inhibitory action. In the absence of drugs, the release of histamine was not affected by the pH of the medium, but the inhibitory effects of the drugs increased with increase in pH. The percent inhibition of histamine release by these drugs at each pH was plotted against the calculated concentration of the nonionized form of the drug, according to the Henderson-Hasselbalch equation. The inhibitory action was correlated with the concentration of nonionized molecules, which readily penetrate the cell membrane. From the interaction of lidocaine with the phospholipid bilayer, it was concluded that this drug penetrates the lipid bilayer and that this effect increases with increasing pH of the medium. Thus, it seems that it is the nonionized form of local anesthetics that inhibits histamine release and that it is nonionized molecules that penetrate the mast cell membrane.

Inhibitory effect of local anesthetics on histamine release from mast cells(report 3).

Lidocaine inhibits the histamine release from rat mast cells, but enhances the release at higher concentrations (H.G.Johnson et al., Agents and Actions 9, 239-243, 1979). The mode of action of lidocaine was elucidated by comparison with the action of W49091(charged lidocaine) and benzocaine(uncharged procaine-analog). The effects of lidocaine, benzocaine and W49091 on 45Ca uptake stimulated by concanavalin A(con A, 20 μg/ml) or by A23187(10μM) were compared with the inhibitions of the histamine release by these drugs. At the concentrations of these drugs which inhibit the release maximally, lidocaine (10mM) benzocaine (6mM) and W49091 (60mM) reduced con A-stimu-lated 45Ca uptake by 57%, 83% and 28%, respectively. In the case of A23187, lidocaine(30mM) and W49091(100mM) reduced 45Ca uptake by 58% and 27%, respectively, but benzocaine(10mM) had no effect. Then, we examined the effects of lidocaine and benzocaine on Ca transport mediated by A23187(30μM) in Ca-loaded liposomes. Ca transport was not affected by these drugs. Lidocaine, therefore, did not reduce the ability of A23187, but reduced Ca uptake secondarily. It is concluded that lidocaine not only blocks Ca channel but also affects the process after Ca influx and that it subsequently inhibits histamine release. At and above 30mM of lidocaine, lactate dehydrogenase was also released, indicating that the higher concentrations of lidocaine release histamine by a cytotoxic mechanism.