Biomedical subjects

P Kraft

Publications and source records attributed to P Kraft.

At least 19 recordsLinked to original sources

PubMed2006

JNJ-10280205 and JNJ-10287069: Novel PDE5 inhibitors as clinical candidates for erectile dysfunction.

Phosphodiesterase 5 (PDE5) inhibitors are efficacious in treating patients with erectile dysfunction. New PDE5 inhibitors with different selectivity and pharmacokinetic profiles have been vigorously pursued. Here we report two novel, potent, and selective PDE5 inhibitors, JNJ-10280205 and JNJ-10287069, with Ki values of 0.05 and 0.12 nM, respectively. Both compounds displayed superior selectivity against PDE1-4 and -6 when compared to sildenafil. In the anesthetized dogs, JNJ-10280205 and JNJ-10287069 exhibited similar efficacy as sildenafil in enhancing erectile functions, with no significant effect on cardiovascular parameters. Pharmacokinetic studies showed that JNJ-10287069 had better oral bioavailability than JNJ-10280205 in several animal species. In vitro study suggested that cytochrome P450 (CYP) 3A4 played a major role in the metabolism of both compounds. The compounds inhibited some of the CYP450 enzymes and the human ether-a-go-go (HERG) channel at much higher concentrations than that required to inhibit PDE5, thus, no cross inhibition would be expected at therapeutic doses. Both compounds are suitable clinical candidates.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2005

A candidate gene approach to searching for low-penetrance breast and prostate cancer genes.

Most cases of breast and prostate cancer are not associated with mutations in known high-penetrance genes, indicating the involvement of multiple low-penetrance risk alleles. Studies that have attempted to identify these genes have met with limited success. The National Cancer Institute Breast and Prostate Cancer Cohort Consortium--a pooled analysis of multiple large cohort studies with a total of more than 5,000 cases of breast cancer and 8,000 cases of prostate cancer--was therefore initiated. The goal of this consortium is to characterize variations in approximately 50 genes that mediate two pathways that are associated with these cancers--the steroid-hormone metabolism pathway and the insulin-like growth factor signalling pathway--and to associate these variations with cancer risk.

Breast Neoplasms↗

PubMed2001

Constructing conformationally constrained macrobicyclic musks.

To investigate the structure-odor correlation of musks, (12R)-12-methyl-13-tridecanolide (1), a macrocyclic musk, and 13-tridecanolide, its non-musky demethyl analogue, were conformationally constrained by introduction of methylene bridges between C-3 and C-8 or C-9. These [7.5.1]- and [8.4.1]-macrobicycles were synthesized starting from bicyclo[5.3.1]undec-8-en-9-one (3) and bicyclo[4.3.1]dec-7-en-8-one (8), respectively, by a sequence consisting of catalytic hydrogenation, alpha-alkylation with a TBS-protected (tert-butyldimethylsilyl) hydroxy halide, acid-catalyzed cyclization, oxidative cleavage of the formed enol ether double bond, and subsequent reduction of the carbonyl group via its tosylhydrazone. The compound (1R,6R,9R)-(+)-6-methyl-4-oxa-bicyclo[7.5.1]pentadecan-3-one (22) was found to possess the most pronounced musk odor, and this was rationalized by a superposition analysis with the polycyclic aromatic musk odorant (4S,7R)-Galaxolide (2). In its (1S,6R,9S)-(+)-stereoisomer 23 as well as in (1S,6R, 10R)-(+)-6-methyl-4-oxabicyclo[8.4.1]-pentadecan-3-one (18) the (6R)-methyl group seems to hinder the interaction with the musk receptor, while the demethyl compounds 7 and 12 showed only very faint odors.

Bridged Bicyclo Compounds↗

PubMed2001

Simple bedside additive tool for prediction of in-hospital mortality after percutaneous coronary interventions.

BACKGROUND: Risk-adjustment models for percutaneous coronary intervention (PCI) mortality have been recently reported, but application in bedside prediction of prognosis for individual patients remains untested. METHODS AND RESULTS: Between July 1, 1997 and September 30, 1999, 10 796 consecutive procedures were performed in a consortium of 8 hospitals. Predictors of in-hospital mortality were identified by use of multivariate logistic regression analysis. The final model was validated by use of the bootstrap technique. Additional validation was performed on an independent data set of 5863 consecutive procedures performed between October 1, 1999, and August 30, 2000. An additive risk-prediction score was developed by rounding coefficients of the logistic regression model to the closest half-integer, and a visual bedside tool for the prediction of individual patient prognosis was developed. In this patient population, the in-hospital mortality rate was 1.6%. Multivariate regression analysis identified acute myocardial infarction, cardiogenic shock, history of cardiac arrest, renal insufficiency, low ejection fraction, peripheral vascular disease, lesion characteristics, female sex, and advanced age as independent predictors of death. The model had excellent discrimination (area under the receiver operating characteristic curve, 0.90) and was accurate for prediction of mortality among different subgroups. Near-perfect correlation existed between calculated scores and observed mortality, with higher scores associated with higher mortality. CONCLUSIONS: Accurate predictions of individual patient risk of mortality associated with PCI can be achieved with a simple bedside tool. These predictions could be used during discussions of prognosis before and after PCI.

Age Factors↗

PubMed2001

Mass spectrometric analysis of cyanogen bromide fragments of integral membrane proteins at the picomole level: application to rhodopsin.

Advances in time-of-flight mass spectrometry allow unit mass resolution of proteins and peptides up to about 6000 Da molecular weight. Identification of larger proteins and study of their posttranslational or experimental modifications by mass analysis is greatly enhanced by cleavage into smaller fragments. Most membrane proteins are difficult to mass analyze because of their high hydrophobicity, typical expression in low quantities, and because the detergents commonly used for solubilization may be deleterious to mass analysis. Cleavage with cyanogen bromide is beneficial for analysis of membrane proteins since the methionine cleavage sites are typically located in hydrophobic domains and cleavage at these points reduces the size of the hydrophobic fragments. Cyanogen bromide also gives high cleavage yields and introduces only volatile contaminants. Even after cleavage membrane proteins often contain fragments that are difficult to chromatograph. Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) is capable of analyzing complex mixtures without chromatography. We present a MALDI MS method that quickly and reliably identifies the cyanogen bromide fragments and posttranslational modifications of reduced and alkylated bovine rhodopsin from as little as 30 pmol of rhodopsin in detergent-solubilized retinal rod disk membranes, using 1-5 pmol of digest per sample. The amino acid sequences of some of the peptides in the digest were confirmed by post source decomposition MS analysis of the same samples. The method appears to be general and applicable to the analysis of membrane proteins and the protein composition of membrane preparations.

Amino Acid Sequence↗

PubMed2001

Enantioselectivity of the musk odor sensation.

This brief review, the summary of a talk at the Symposium on Biological Chirality 2000 in Szeged, Hungary, illustrates what chiral recognition tells us about the molecular parameters of the musk odor sensation. While the enantioselectivity of odor perception is strong evidence for the key role of proteinogenic receptors in the molecular mechanism of olfaction, the quantitative and qualitative odor differences of enantiomers are often not very pronounced, as in the case of muscone (17/26). In those cases, however, where there is strong enantiodiscrimination, we find most intense musk odorants with very low odor thresholds, such as (-)-(12R)-12-methyl-9-oxa-14-tetradecanolide (35), (12R;9Z)-12-methyl-14-tetradec-9-enolide [(R)-Nirvanolide, 38], and (-)-(4S;7R)-1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran [(-)-(4S;7R)-Galaxolide, 57], the latter being rather rigid. We thus can assume the geometry of the musk receptor to be fairly complementary to these compounds, which therefore can serve as templates for the design of new musk odorants.

Fatty Acids, Monounsaturated↗

PubMed2001

A robust score test for linkage disequilibrium in general pedigrees.

Many family-based tests of linkage disequilibrium are not valid when related nuclear families from larger pedigrees are used, or when independent nuclear families with multiple cases are used. The Pedigree Disequilibrium Test (PDT) proposed by Martin et al. [Am J Hum Genet 67:146-54, 2000] avoids these problems. This paper sketches an extension of the PDT that can account for measured covariates. Where the PDT is based on allele-counting methods, this extension is based on conditional logistic regression. Versions of these statistics were used to test for association between disease and two known functional single nucleotide polymorphisms (SNPs) on gene 1 and gene 6 and one inert SNP on gene 7 in the first 25 replicates of the simulated population-isolate data. The new method was also used to test for linkage disequilibrium after correcting for the effect of the environmental factor E1. The PDT and the conditional logistic extension had similar power to detect the functional SNPs (100% for gene 1, approximately 50% for gene 6) and appropriate type I error rates for the inert SNP. Correcting for E1 slightly increased power to detect the association between gene 6 and disease.

Genetic Predisposition to Disease↗

PubMed2001

Identification and functional study of phosphodiesterases in rat urinary bladder.

Abstract Cyclic nucleotides are important secondary messengers involved in modulating the contractility of various smooth muscles. Phosphodiesterases (PDE) play important roles in this process by modulating the levels of cyclic nucleotides and their duration of action. This study was designed to identify and characterize the PDE isoenzymes in rat urinary bladder and to evaluate their roles in regulating bladder smooth muscle tone. The involvement of cAMP and cGMP pathways in this process was also assessed. The studies were carried out with tissues from male and female rats and no significant sex-related difference was found in the results. Utilizing the unique pharmacological properties of different isoenzymes, PDE1, 2, 3, 4, and 5 were identified in rat bladder. Organ bath experiments showed that forskolin was most potent in relaxing pre-contracted rat bladder strips while sodium nitroprusside was moderately effective, suggesting the relaxation was mainly mediated by the cAMP pathway and that the cGMP pathway is moderately involved. For PDE inhibitors, the non-specific inhibitor papaverine was most effective in relaxing pre-contracted bladder strips. Among isoenzyme-selective inhibitors, vinpocetine, EHNA, and sildenafil induced more relaxation than milrinone and rolipram.

Animals↗

PubMed2001

Stenotherms at sub-zero temperatures: thermal dependence of swimming performance in Antarctic fish.

We examined the burst swimming performance of two Antarctic fishes, Trematomus bernacchii and T. centronotus, at five temperatures between -1 degrees C and 10 degrees C. As Antarctic fishes are considered one of the most cold specialised and stenothermal of all ectotherms, we predicted they would possess a narrow thermal performance breadth for burst swimming and a correlative decrease in performance at high temperatures. Burst swimming was assessed by videotaping swimming sequences with a 50-Hz video camera and analysing the sequences frame-by-frame to determine maximum velocity, the distance moved throughout the initial 200 ms, and the time taken to reach maximum velocity. In contrast to our prediction, we found both species possessed a wide thermal performance breadth for burst swimming. Although maximum swimming velocity for both T. bernacchii and T. centronotus was significantly highest at 6 degrees C, maximum velocity at all other test temperatures was less than 20% lower. Thus, it appears that specialisation to a highly stable and cold environment is not necessarily associated with a narrow thermal performance breadth for burst swimming in Antarctic fish. We also examined the ability of the Antarctic fish Pagothenia borchgrevinki to acclimate their burst-swimming performance to different temperatures. We exposed P. borchgrevinki to either -1 degrees C or 4 degrees C for 4 weeks and tested their burst-swimming performance at four temperatures between -1 degrees C and 10 degrees C. Burst-swimming performance of Pagothenia borchgrevinki was unaffected by exposure to either -1 degrees C or 4 degrees C for 4 weeks. Maximum swimming velocity of both acclimation groups was thermally independent over the total temperature range of 1 degrees C to 10 degrees C. Therefore, the loss of any capacity to restructure the phenotype and an inability to thermally acclimate swimming performance appears to be associated with inhabiting a highly stable thermal environment.

Acclimatization↗

PubMed2001

Effects of propafenone on anisotropic conduction properties within the three-dimensional structure of the canine ventricular wall.

BACKGROUND: Structural complexities of the intact ventricular wall cause a very complex spread of activation. The effects of regional tissue damage and of antiarrhythmic drugs on directional differences in activation should help to further elucidate intramural conduction patterns. METHODS AND RESULTS: In 10 healthy dogs and in 5 dogs with subacute anterior wall infarction, 6 parallel rows of 6 needle electrodes with 4 bipolar electrode pairs per needle were inserted into the left anterior ventricular wall. Using a computerized multiplexer-mapping system, the spread of activation in epi-, endo- and midmyocardial muscle layers and in the surviving epicardium, respectively, was reconstructed. Marked differences in conduction velocities relative to fiber orientation were evident in the surviving epicardium of infarcted hearts. Directional differences in conduction velocities, although less pronounced, were still preserved throughout the intact ventricular wall. Epicardial transverse conduction in intact hearts was significantly faster than transverse conduction in infarcted hearts (0.87 +/- 0.11 m/s vs 0.68 +/- 0.1 m/s). In normal hearts, propafenone (2 mg/kg) decreased conduction velocities primarily in longitudinal directions (-27 +/- 10%), but also moderately in transverse directions (-13 +/- 7 %) of all muscle layers, with no significant effect on straight (-4 +/- 8 %), but on oblique transmural conduction (-33 +/- 18 %). In infarcted hearts propafenone decreased conduction particularly in longitudinal direction (-23 +/- 14 %) without affecting conduction transverse to the fiber orientation (+3 +/- 6%). CONCLUSIONS: Longitudinal intramural shortcircuits reduce directional differences in activation. Transmural infarction results in a loss of alternative intramural pathways, unmasking marked anisotropy in the surviving epicardium. Conduction delay in intramural pathways explains the effects of propafenone on transverse and oblique transmural conduction. Primarily longitudinal conduction delay results in reduced tissue anisotropy.

Animals↗

PubMed2001

Toward an integrative model of suicide attempt: a cognitive psychological approach.

Applying a cognitive approach, the purpose of the present study was to expand previous research on stress-vulnerability models of depression and problem-solving deficits, as it relates to suicide attempt. Structural equation modelling, involving latent variables, was used to evaluate (a) whether low self-esteem, a low sense of self-efficacy, loneliness, and divorce constituted vulnerability factors for the development of depression; (b) whether hopelessness and suicidal ideation mediated the relationship between depression and suicide attempt; and (c) whether problem-solving deficits mediated the relationship between the vulnerability factors and suicide attempt, separate from depression/hopelessness. A total of 123 individuals, aged 18-75 years, participated in the study (72 suicide attempters and 51 psychiatric outpatients with no history of suicidal behavior). The results indicated a two path model of suicide attempt. The first path began with low self-esteem, loneliness, and separation or divorce, which advanced to depression, and was further mediated by hopelessness and suicidal ideation which led to suicide attempt. The second path developed from low self-esteem and a low sense of self-efficacy and advanced to suicide attempt, mediated by a negative appraisal of one's own problem-solving capacity, and poor interpersonal problem-solving skills. The importance of addressing both depression/hopelessness, and problem-solving deficits when working with suicide attempters is noted.

Adolescent↗

PubMed2000

Nonsteroidal progesterone receptor ligands with unprecedented receptor selectivity.

We have characterized a series of nonsteroidal progesterone receptor ligands, the tetrahydropyridazines. Compounds in this series, exemplified by RWJ 26819, demonstrate high affinity and unprecedented specificity for the progesterone receptor relative to other steroid hormone receptors. Like steroidal progestins, RWJ 26819 induces binding of the receptor to a progesterone response element in vitro, and stimulates gene expression in and proliferation of T47D human breast cancer cells. When administered to rabbits orally or subcutaneously, the compound induces histological changes in the uterine lining comparable to those induced by levonorgestrel. It also inhibits ovulation in monkeys. Though less potent in cells and in animal models than would be predicted from binding affinity alone, their enhanced selectivity suggests that they could be effectively used in a clinical setting. Most of the tetrahydropyridazines synthesized are progestin agonists or mixed agonists and antagonists in vitro; however, one compound with antagonist activity in the rabbit uterine transformation assay has been identified.

Alkaline Phosphatase↗

PubMed2000

Odds and Trends: Recent Developments in the Chemistry of Odorants Note on trademarks: Words which we know or have reason to believe constitute registered trademarks (R) are designated as such. However, neither the presence nor absence of such designation should be regarded as affecting the legal status of any trademark. Note on perfume analysis: The quoted percentages of perfume raw materials in market products are rounded figures. They are often derived from area percentages from the GC (FID) analysis, and are thus subject to analytical error.

Fragrance chemistry is, together with the closely related area of flavor chemistry, one of the few domains, if not the only one, in which chemists can immediately experience structure-activity relationships. This review presents structure-odor correlations and olfactophore models for the main odor notes of perfumery: "fruity", "marine", "green", "floral", "spicy", "woody", "amber", and "musky". New trendsetters and so-called captive odorants of these notes are introduced, and recent activities and highlights in fragrance chemistry are summarized. The design of odorants, their chemical synthesis, and their use in modern perfumery is discussed. Our selection is guided and illustrated by creative fragrances, and features new odorants which encompassed current trends in perfumery. New odorants for grapefruit and blackcurrant, for galbanum, and leafy top notes are presented. Compounds with fashionable marine, ozonic, and aquatic facets are treated, as well as new odorants for classical lily-of-the-valley, rose, and jasmine accords. Compounds with sweet and spicy tonalities are also discussed, as are the most recent developments for woody notes such as sandalwood and vetiver. We conclude with musky and ambery odorants possessing uncommon or unusual structural features. Some odor trends and effects are illustrated by microencapsulated fragrance samples, and areas where there is need for the development of new synthetic materials and methodologies are pointed out. Thus, chemists are invited to explore fragrance chemistry and participate in the design and synthesis of new odorants. This review gives the latest state of the art of the subject.

Journal Article↗

PubMed2000

Testing linkage disequilibrium in sibships.

We describe the use of multivariate regression for testing allelic association in the presence of linkage, using marker genotype data from sibships. The test is valid, provided that the correct mean structure is modeled but does not require the correlation structure within families to be specified. The test can be implemented using standard statistical software such as the SAS programming language. In a simulation study, we evaluated this new test in comparison with one from a standard, matched-case-control analysis. First, we noted that the genetic effect needed to be quite extreme before residual familial correlation due to linkage led to false inference using the standard, matched-pair analysis. Second, we showed that under examples of extreme residual familial correlation, the new test had the correct test size. Third, we found that the test was more powerful than the sibship disequilibrium test of Horvath and Laird. Finally, we concluded that although the standard analysis may lead to correct inference for practical purposes, the new test is valid, even under extreme residual familial correlation and with no cost in power at the causal locus.

Alleles↗

PubMed2000

Electrophysiologic effects of the new I(Ks)-blocking agent chromanol 293b in the postinfarction canine heart. Preserved positive use-dependence and preferential prolongation of refractoriness in the infarct zone.

OBJECTIVES: Aim of the present study was to investigate site- and rate dependent effects of the IKs-blocking agent chromanol 293b on conduction and refractoriness in normal, infarcted, and transitional regions of in-situ canine hearts. METHODS: In five dogs with subacute myocardial infarction, three-dimensional mapping was performed after insertion of 6 x 6 needle electrodes in the left ventricle. Before and after application of chromanol 293b (10 mg/kg), activation patterns and local refractory periods (ERPs) at pacing intervals of 300, 500 and 850 ms were obtained for the surviving epicardial muscle layer of the infarct zone (IZ) and for epi-, endo-, and midmyocardial muscle layers of both the normal zone (NZ) and the border zone (BZ) separating normal and infarcted areas. RESULTS: At baseline, both the NZ and the BZ exhibited uniform ERPs throughout the ventricular wall. Epicardial ERPs were longer in the IZ than in the NZ, and intermediate in the BZ. Chromanol 293b did not affect total activation times. However, at fast heart rates regional areas of slow conduction occurred. Chromanol 293b ubiquitously prolonged local ERPs, most markedly in the IZ. A preferential effect on individual muscle layers of the NZ or BZ and, thus, drug-induced transmural dispersion of ERP could not be observed. Again ubiquitously, the effect on ERP was more pronounced at faster than at slower heart rates, that is, positive use-dependent. At a basic cycle length of 300 ms, chromanol 293b prolonged local ERPs in the IZ by 46 +/- 24 %, in the BZ by 34 +/- 26%, and in the NZ by 20 +/- 17% (p < or = 0.05). CONCLUSIONS: At least in theory, the electrophysiologic properties of chromanol 293 b, that is, preferential prolongation of refractoriness in ischemic myocardium, more pronounced at faster than at slower heart rates, but homogeneously throughout the intact ventricular wall, appear to be favorable. Whether this translates into a clinical benefit, particularly in the treatment of ischemia-related ventricular tachyarrhythmias, remains to be determined.

Animals↗

PubMed2000

Centriacinar region inflammatory disease in young individuals: a comparative study of Miami and Los Angeles residents.

Semiquantitative measurements of chronic inflammation of the centriacinar region (proximal acinus of lung) were compared between 20 Miami and 18 Los Angeles residents (ages 11-30 years) for whom smoking histories were available. Mean extent and severity scores of four lung sites were higher for Los Angeles than Miami residents, with effect of city statistically significant for extent (P=0.02). Also, maximum scores for extent and severity by city were significantly greater for Los Angeles residents (P=0.02, each), but not by smoking history. Smokers did have higher scores for mean extent and severity (by lung site and smoking history), but neither this nor inclusion of smoking and city in the model reached significance. With respect to maximum extent and maximum severity scores, a stratified comparison of cities by smoking history showed a trend (not significant) toward higher scores for Los Angeles residents. Mean extent and severity scores for the lower lobe were higher for basilar sections than for apical sections (each P<0.001). Cumulative data indicate that expanded pathologic studies are essential for efforts to complete a convergence of epidemiological and experimental data implicating exceedences of the Federal ozone standard as a contributor to human lung injury.

Adolescent↗

PubMed2000

Bias and efficiency in family-based gene-characterization studies: conditional, prospective, retrospective, and joint likelihoods.

We revisit the usual conditional likelihood for stratum-matched case-control studies and consider three alternatives that may be more appropriate for family-based gene-characterization studies: First, the prospective likelihood, that is, Pr(D/G,A second, the retrospective likelihood, Pr(G/D); and third, the ascertainment-corrected joint likelihood, Pr(D,G/A). These likelihoods provide unbiased estimators of genetic relative risk parameters, as well as population allele frequencies and baseline risks. The parameter estimates based on the retrospective likelihood remain unbiased even when the ascertainment scheme cannot be modeled, as long as ascertainment only depends on families' phenotypes. Despite the need to estimate additional parameters, the prospective, retrospective, and joint likelihoods can lead to considerable gains in efficiency, relative to the conditional likelihood, when estimating genetic relative risk. This is true if baseline risks and allele frequencies can be assumed to be homogeneous. In the presence of heterogeneity, however, the parameter estimates assuming homogeneity can be seriously biased. We discuss the extent of this problem and present a mixed models approach for providing consistent parameter estimates when baseline risks and allele frequencies are heterogeneous. The efficiency gains of the mixed-model prospective, retrospective, and joint likelihoods relative to the efficiency of conditional likelihood are small in the situations presented here.

Alleles↗

PubMed2000

Role of sodium channels in ventricular fibrillation: a study in nonischemic isolated hearts.

Because the role of sodium channels in the initiation and maintenance of VF is not fully elucidated, we studied the significance of sodium channel activity in VF using sodium channel blockers. In nonischemic isolated feline hearts, the following electrophysiologic parameters were measured before and after application of tetrodotoxin (5 x 10(-7) M, n = 6) or lidocaine (1 x 10(-5) M, n = 8): (a) during pacing, epicardial conduction time; refractoriness; the fastest rate for 1:1 pacing/response capture, and all tissue resistivity, indirectly reflecting intercellular electrical resistance; (b) during 8 min of electrically induced tachyarrhythmias, all tissue resistivity; peak frequency (to measure average frequency based on fast-Fourier transformation analysis); and normalized entropy (to measure the degree of arrhythmia organization). In nonischemic isolated rabbit hearts (n = 4), three-dimensional mapping was performed before and after application of lidocaine (1 x 10(-5) M). In feline hearts, lidocaine and tetrodotoxin application resulted in: (a) more spontaneous arrhythmia termination (63-67%) than in nontreated hearts (7%); (b) transformation from mainly VF into ventricular tachycardia with increased organization; and (c) prolongation of conduction time (155-248%) (p < 0.01 for all parameters). The ventricular refractory period was slightly prolonged by tetrodotoxin in the right ventricle and exhibited rate-dependent shortening in control and with lidocaine. Tetrodotoxin and lidocaine reduced the pacing rate for 1:1 pacing/response capture, and all tissue resistivity was not significantly affected. Peak frequency was decreased by tetrodotoxin and lidocaine mainly in the left ventricle (p < 0.01). In nontreated left ventricles, peak frequency was increased over time but was attenuated by lidocaine. In isolated rabbit hearts, several simultaneous wave fronts were detected during VF in nontreated hearts and were reduced to only one or two major wavefronts after application of lidocaine. Suppression of sodium channel activity that primarily slowed conduction time and had little or no effect on ventricular refractory period and all tissue resistivity resulted in less stable and more organized arrhythmias and reduced tachyarrhythmia rate compared with nontreated hearts. These results suggest an active role for sodium channels in the maintenance of ventricular fibrillation.

Anesthetics, Local↗