Fine mapping of a major QTL qPA7-1 for low hydrocyanic acid content in sorghum-sudangrass hybrid.

The purpose of this study was to study the genetic mechanism of low hydrocyanic acid (HCN) content. The segregation of HCN content trait in fresh stems and leaves was determined in the sorghum (Sorghum bicolor (L.) Moench)-sudangrass (Sorghum sudanense (Piper) Stapf) hybrid F2 population (N = 1200), also used to detect a quantitative trait locus (QTL) for HCN content. Our hypothesis was that the additive effect of QTL was negative, showing that QTL was associated with low HCN. In the present research, a total of 11 simple sequence repeats (SSR) polymorphic primers were screened, and four SSR markers associated with low HCN content were developed based on the bulked segregant analysis method. A high-resolution genetic linkage group of the previously known qPA7-1 locus of the low HCN trait was constructed by analyzing different populations, families, and recombinants. Then, the QTL qPA7-1 of sorghum-sudangrass hybrid was fine-mapped to a 203.6 kb region between markers SORBI4G4-120 and SORBI4G4-680, and seven candidate genes for low HCN were predicted in this region based on sequence comparison with the sorghum reference genome. According to gene annotation, the candidate genes related to low HCN content may be different from those involved in the known regulation mode of sorghum dhurrin biosynthesis and metabolism.

Cassava dreg as replacement of corn in goat kid diets.

The effects of corn replacement by cassava dreg in diets of crossbred goat kids were evaluated. We tested the impacts of 0, 33, 66 and 100% replacement on intake, digestibility, feeding behaviour, performance and carcass characteristics. Thirty-six goat kids, aged between 4 and 5 months and with initial body weights of 17.61 ± 1.98 kg, were used in a completely randomised design. Analysis of regression revealed a negative linear effect on neutral detergent fibre (NDF) intake and a positive linear effect on non-fibrous carbohydrates (NFC) and hydrocyanic acids (HCN) intake. Cassava dreg use had a positive linear effect on organic matter digestibility and non-fibrous carbohydrates. Based on our results, cassava dreg use did not negatively impact animal performance, feeding behaviour and carcass characteristics, suggesting that it may replace corn up to 100% in the diets of confined goat kids.

A QM/MM study of the reaction mechanism of (R)-hydroxynitrile lyases from Arabidopsis thaliana (AtHNL).

Hydroxynitrile lyases (HNLs) catalyze the conversion of chiral cyanohydrins to hydrocyanic acid (HCN) and aldehyde or ketone. Hydroxynitrile lyase from Arabidopsis thaliana (AtHNL) is the first R-selective HNL enzyme containing an α/ß-hydrolases fold. In this article, the catalytic mechanism of AtHNL was theoretically studied by using QM/MM approach based on the recently obtained crystal structure in 2012. Two computational models were constructed, and two possible reaction pathways were considered. In Path A, the calculation results indicate that the proton transfer from the hydroxyl group of cyanohydrin occurs firstly, and then the cleavage of C1-C2 bond and the rotation of the generated cyanide ion (CN(-)) follow, afterwards, CN(-) abstracts a proton from His236 via Ser81. The C1-C2 bond cleavage and the protonation of CN(-) correspond to comparable free energy barriers (12.1 vs. 12.2 kcal mol(-1)), suggesting that both of the two processes contribute a lot to rate-limiting. In Path B, the deprotonation of the hydroxyl group of cyanohydrin and the cleavage of C1-C2 bond take place in a concerted manner, which corresponds to the highest free energy barrier of 13.2 kcal mol(-1). The free energy barriers of Path A and B are very similar and basically agree well with the experimental value of HbHNL, a similar enzyme of AtHNL. Therefore, both of the two pathways are possible. In the reaction, the catalytic triad (His236, Ser81, and Asp208) acts as the general acid/base, and the generated CN(-) is stabilized by the hydroxyl group of Ser81 and the main-chain NH-groups of Ala13 and Phe82.

A free cyanohydrin as arms and armour of Marasmius oreades.

Cyanogenic plants and fungi are widespread in nature. Although the origin of hydrocyanic acid in plants has been studied in detail, little is known about its origin in fungi. Here, we report the identification of the cyanohydrin of glyoxylic acid as the precursor of hydrocyanic acid in the fungus Marasmius oreades and several other cyanogenic fungi. Moreover, a feeding experiment revealed glycine as biosynthetic precursor of the cyanohydrin of glyoxylic acid. Thus, the cyanogenesis of M. oreades and other fungi is fundamentally different from cyanogenesis in plants.

Detection of Cyanide in a Decomposed Exhumed Body: A Case Report.

Cyanide is a lethal poison that induces immediate fatality. Infrequently employed as a homicidal poison, it is not an ideal choice for homicide as it causes a 'dramatic' death causing suspicion among others. Cyanide is a rapidly metabolized poison that also rapidly disintegrates after death, posing challenges for chemical analysis, particularly when dealing with decomposed bodies. Detection of cyanide from a decomposed body is infrequent. A suspected case of intentional poisoning resulting in death was interred without conducting a postmortem examination. The exhumation process revealed the presence of hydrogen cyanide in the postmortem fluids collected from the body cavities three years after interment.

Effects of Aspergillus niger on cyanogenic glycosides removal and fermentation qualities of ratooning sorghum.

Introduction: Cyanogenic glycosides (CNglcs) are bioactive plant products involving in plant defense against herbivores by virtue of their abilities to release toxic hydrogen cyanide (HCN). Aspergillus niger has been shown to be effective in producing ß-glucosidase, which could degrade CNglcs. However, whether A. niger could remove CNglcs under ensiling conditions is still unknown. Methods: In this study, we first investigated the HCN contents in ratooning sorghums for two years, then the sorghums were ensiled with or without the addition of A. niger. Results: Two years' investigation indicated that the contents of HCN in fresh ratooning sorghum were larger than 801 mg/kg FW (fresh weight), which could not be reduced by silage fermentation under safety threshold (200 mg/kg FW). A. niger could produce ß-glucosidase over a range of pH and temperature, which degraded the CNglcs and removed the hydrogen cyanide (HCN) at early days of ratooning sorghum fermentation. The addition of A. niger (2.56 × 107 CFU/ml) altered the microbial community, increased bacterial diversity, improved the nutritive qualities, and reduced the HCN contents in ensiled ratooning sorghum lower than 100 mg/kg FW after 60 days of fermentation. Overall, the addition of 150 ml A. niger + 50 ml sterile water per 3 kg silage could efficiently remove CNglcs from ratooning sorghum silage. Conclusion: In conclusion, A. niger could produce ß-glucosidase which degraded the CNglcs during the early days of fermentation, benefiting the ensiling process and improving the utilization of ratooning sorghum.

Investigation of an artificial solution degradant of linagliptin: An undesired linagliptin urea derivative generates in sample preparation of linagliptin tablet treated by sonication in acetonitrile containing diluent.

During the related substances testing method development for linagliptin tablet, an unknown peak was observed in HPLC chromatograms with a level exceeding the identification threshold. By using a strategy that combines LC-PDA/UV-MSn with mechanism-based stress studies, the unknown peak was rapidly identified as linagliptin urea, a solution degradant that is caused by the reaction between the API and hydrocyanic acid with sonication treatment to accelerate dissolution of the drug substance in sample preparation of linagliptin tablets, and hydrocyanic acid is a known impurity in HPLC grade acetonitrile and acetonitrile is used as part of diluent. The mechanism of the solution degradation chemistry was verified by stressing linagliptin API with trimethylsilyl cyanide (TMSCN, which can give off HCN slowly in the presence of water) treated with sonication in the sample preparation. Further investigation found that when the sonication treatment was replaced by vortex vibration in the process of the sample preparation, the RRT 1.28 species was decreased to below the level of the detection limit (0.02%). The structure of this impurity was further confirmed through the synthesis of the impurity and subsequent structure characterization by 1D and 2D NMR. Due to the presence of trace amount of HCN in HPLC grade acetonitrile, these types of solution degradation would likely occur in analysis of pharmaceutical finished products containing APIs with primary and secondary amine moieties drug product during sample preparations, particularly when sonication treatment is used to accelerate dissolution of drug substance from the finished drug product. In the GMP quality control laboratories, such events may trigger undesirable out-of-specification (OOS) events. Hence, the results of this paper can help to prevent these events from happening in the first place or resolve these OOS events in GMP laboratories.

Development and validation of eight cyanogenic glucosides via ultra-high-performance liquid chromatography-tandem mass spectrometry in agri-food.

An ultra-high-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS) method was established and validated for the simultaneous quantification of eight cyanogenic glucosides (CNGs) in agri-food. The eight CNGs were linamarin, lotaustralin, linustatin, neolinustatin, taxiphyllin, amygdalin, dhurrin and prunasin. CNGs were extracted with aqueous methanol and cleaned via solid-phase extraction. Analytes were separated with a C18 column via gradient elution. MS/MS analysis was performed with electrospray ionisation in positive mode. Quantification was performed in multiple reaction monitoring mode. Satisfactory validation results were obtained in terms of linearity, sensitivity, precision and accuracy, matrix effect and stability. The method was applied in typical cyanogenic agri-food. CNGs in cassava, linseed, bamboo, sorghum, apricot, almond and lima bean were analyzed.

Oven drying and hot water cooking processes decrease HCN contents of cassava leaves.

The aim of this work was to study the effects of temperature and time of oven drying and hot water cooking processes on HCN (hydrocyanic acid) degradation of cassava leaves as a contribution for obtaining a safe product for human consumption. Nine varieties of cassava leaves collected in the Amazonian region of Brazil (Pará State) were characterized regarding moisture, pH, total acidity, ashes, total lipids, total protein, water activity, carbohydrates, total energetic value and HCN contents. The leaves of the three cassava varieties, which presented the highest HCN contents, were submitted to the thermal degradation of HCN, under drying and boiling conditions. All the leaves presented similar physicochemical characteristics and the HCN contents varied from 90.6 to 560.9 mg HCN/kg fresh leaves (total HCN) and from 16.6 to 59.2 mg HCN/kg fresh leaves (free HCN). Thermal degradation studies on HCN showed that the drying and boiling processes were effective on total HCN removal after 180 min. Furthermore, a remarkable decrease in HCN contents was observed after 20 min of boiling. Regarding free HCN, the drying method was more effective than boiling, showing high degradation percentages: 74.1%-92.2% to 1.1%-72.4%, respectively.

Assessment of a decontamination process for hydrocyanic acid in linseed intended for use in animal feed.

Following a request from the European Commission, the EFSA Panel on Contaminants in the Food Chain (CONTAM) provided a scientific opinion on the assessment of a decontamination process for the enzymatic treatment and subsequent heating of linseed, in order to reduce the amount of hydrocyanic acid (HCN) present as cyanogenic glycosides. Specifically, it is required that the feed decontamination process is compliant with the acceptability criteria specified in the Commission Regulation (EU) 2015/786 of 19 May 2015. With this aim, the CONTAM Panel assessed the data provided by the feed business operator with respect to the efficacy of the process to remove the contaminant from the linseed batches and on information demonstrating that the process does not adversely affect the characteristics and the nature of the product. The data enabled the Panel to conclude that in agreement with the literature the process was able to remove HCN by about 90%, and that it is possible to meet the current EU requirements for quality of linseed with respect to HCN, provided the level of contamination of untreated linseed would be within the range of the tested batches. The Panel noted that the amounts of other products formed during the enzymatic process and remaining in the treated material are not of toxicological concern. The experimental data provided by the feed business operator showed that the characteristics of linseed were not adversely affected by the decontamination process. The CONTAM Panel concluded that, on the basis of the information submitted by the feed business operator, the proposed decontamination process to remove HCN from linseed by means of enzymatic release and subsequent evaporation was compliant with the acceptability criteria provided for in Commission Regulation (EU) 2015/786 of 19 May 2015.

Past, present and future of cyanide antagonism research: From the early remedies to the current therapies.

This paper reviews milestones in antidotal therapies for cyanide (CN) spanning early remedies, current antidotal systems and research towards next generation therapies. CN has been a part of plant defense mechanisms for millions of years. It became industrially important in the nineteenth century with the advent of CN assisted gold mining and the use of CN as a pest control agent. The biochemical basis of CN poisoning was actively studied and key mechanisms were understood as early as 1929. These fundamental studies led to a variety of antidotes, including indirect CN binders that generate methemoglobin, direct CN binders such as hydroxocobalamin, and sulfur donors that convert CN to the less toxic thiocyanate. Research on blood gases at the end of the twentieth century shed new light on the role of nitric oxide (NO) in the body. The discovery of NO's ability to compete with CN for enzymatic binding sites provided a previously missed explanation for the rapid efficacy of NO generating antidotes such as the nitrites. Presently used CN therapies include: methemoglobin/NO generators (e.g., sodium nitrite, amyl nitrite, and dimethyl aminophenol), sulfur donors (e.g., sodium thiosulfate and glutathione), and direct binding agents [(e.g., hydroxocobalamin and dicobalt salt of ethylenediaminetetraacetic acid (dicobalt edetate)]. A strong effort is being made to explore novel antidotal systems and to formulate them for rapid administration at the point of intoxication in mass casualty scenarios. New antidotes, formulations, and delivery systems are enhancing bioavailability and efficacy and hold promise for a new generation of improved CN countermeasures.

Cyanogenic poisoning by spontaneous ingestion of star grass (Cynodon nlemfuensis var. nlemfuensis cv. 'Florico') in cattle / Intoxicação cianogênica pela ingestão espontânea de grama estrela (Cynodon nlemfuensis var. nlemfuensis cv. 'Florico') em bovinos

This study reports the epidemiological data and the clinical-pathological condition of five outbreaks of cyanogenic poisoning in cattle spontaneously ingesting star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. 'Florico'). In all outbreaks, the areas where the plant was previously fertilized with high concentrations of nitrogen and the properties adopted the silvipastoral system. The first clinical signs appeared between 10 and 15 minutes after the first introduction of cattle and were characterized by muscular tremors, dyspnea, moderate tympanism, staggering gait, forced breathing with open mouth, sternal recumbency followed by death after 15 to 30 minutes and/or recovery in a few hours after the signs started. In total, 43 cows have become ill and 18 died. Two necropsies were performed and no significant changes were found except for the presence of the plant near the esophageal sphincter region. No histological lesions were seen through microscopy. Green leaves of the star grass were collected from all properties where the outbreaks occurred and the test of the picro-sodium paper was performed, revealing red-brick coloration in 20 minutes after maceration of the leaves.(AU)

Descrevem-se os dados epidemiológicos e quadro clínico-patológico de cinco surtos de intoxicação cianogênica em bovinos que ingeriram espontaneamente grama estrela (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. 'Florico'). Em todos os surtos, as áreas onde a planta se encontrava haviam sido previamente adubadas com altas concentrações de nitrogênio e as propriedades adotavam o sistema silvipastoril com Eucaliptus sp. Os primeiros sinais clínicos surgiram entre 10 e 15 minutos após a primeira introdução dos bovinos e caracterizou-se por tremores musculares, dispneia, timpanismo moderado, andar cambaleante, respiração forçada com a boca aberta, decúbito esternal seguido de morte após 15 a 30 minutos e/ou, recuperação em poucas horas após início dos sinais. No total, adoeceram 43 vacas e destas 18 morreram. Duas necropsias foram realizadas e não foram encontradas alterações significativas, exceto a presença da planta próxima a região do esfíncter esofágico. Através da microscopia não foram visualizadas lesões histológicas. Folhas verdes da grama estrela foram coletadas de todas as propriedades onde os surtos ocorreram e realizadas o teste do papel picro-sódico, o qual revelou coloração vermelho-tijolo em 20 minutos após maceração das folhas.(AU)

Experimental reproduction of cyanogenic poisoning by star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. "Florico") in cattle / Reprodução experimental de intoxicação cianogênica por grama estrela (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. "Florico") em bovinos

We experimentally reproduced star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. "Florico") poisoning in cattle. Star grass was planted in four shaded (1, 2, 3, and 4) and three sunny paddocks (5, 6, and 7) and were fertilized with the equivalent of 0, 750, 200, or 100 kg/ha urea. Fresh plant leaves were collected from each paddock and fed to 8 calves aged 5 months to 1 year at 10g/kg live weight. Clinical examinations were performed pre- and post-feeding. Fresh leaves were also subjected to sodium picrate paper and diphenylamine tests to evaluate hydrocyanic acid and nitrate concentration, respectively. Clinical signs of poisoning by the star grass cv. "Florico" in cattle were observed 5-15 minutes after ingestion; these included wobbling, muscle tremors, frequent and/or dripping urination, tachycardia, ruminal atony, depression, red ocular mucous membranes, and bright red venous blood. Three animals became severely ill, 4 manifested mild to moderate clinical signs, and 1 did not become ill. The 3 severely ill bovines received a thiosulfate and sodium nitrite solution at a dose of 40ml/100 kg live weight, intravenously (IV). Florico star grass poisoned bovines and the reaction to the sodium picrate paper and diphenylamine tests was more significant for samples cultivated in the shade and with high nitrogen fertilization. Florico grass utilization should be avoided in a silvopastoral system.(AU)

Descreve-se a reprodução experimental da intoxicação cianogênica por grama estrela (Cynodon nlemfuensis vanderyst var. nlemfuensis cv. 'Florico') em bovinos. A grama estrela foi plantada em quatro piquetes em área sombreada (1, 2, 3 e 4) e em três piquetes em área ensolarada (5, 6 e 7) e foram adubados com o equivalente a 0, 750, 200 ou 100kg/ha de ureia. Folhas da planta foram coletadas de cada piquete e imediatamente fornecidas na dose de 10g/Kg de peso vivo para 8 bezerros com idades entre 5 meses a 1 ano. Exames clínicos foram realizados antes e durante fornecimento da planta. Folhas verdes de estrela africana foram submetidas ao teste do papel picro-sódico para verificar a presença de ácido cianídrico e ao teste da difenilamina para avaliar a concentração de nitrato. Sinais clínicos de intoxicação pela grama estrela cv. "Florico" nos bovinos foram observados entre 5 e 15 minutos após o término da ingestão, estes incluíram andar cambaleante, tremores musculares, micção frequente e/ou em gotejamento, taquicardia, atonia ruminal, depressão, mucosas oculares e sangue venoso de coloração vermelho-vivo. Três animais adoeceram gravemente, quatro manifestaram sinais clínicos leves a moderados e um não adoeceu. Os 3 bovinos que adoeceram gravemente receberam solução de tiossulfato e nitrito de sódio na dose de 40ml/100kg de peso vivo, por via endovenosa (IV). Grama estrela florico produziu intoxicação em bovinos e a reação ao teste do papel picro-sódico e difenilamina foi mais significativa para as amostras cultivadas à sombra e com alta adubação nitrogenada. Utilização de grama florico deve ser evitada em sistema silvipastoril.(AU)

Experimental poisoning by cassava wastewater in sheep / Intoxicação experimental por manipueira em ovinos

The processing of Manihot esculenta (cassava) tubers yield different by-products, including cassava wastewater, which is the liquid pressed out of the tuber after it has been mechanically crushed. Cyanide poisoning after ingestion of cassava wastewater has been reported in ruminants and pigs in Northeastern Brazil. With the aim of studying its toxicity, cassava wastewater was administered orally to six sheep at doses of 0.99, 0.75, 0.70, 0.63, and 0.5 mg of hydrocyanic acid kg-1 body weight, which corresponded to 14.2, 10.6, 9.8, 8.89, and 7.1 mL of wastewater kg-1. On the second day, the sheep received a volume of wastewater which corresponded to 0.46, 0.34, 0.31, 0.28, and 0.23 mg of HCN kg-1. A sheep used as control received 9.9 mL of water kg-1 BW. Sheep that received from 0.75 to 0.99 mg kg-1 of HCN on the first day exhibited severe clinical signs of poisoning, and the sheep that received 0.63 and 0.5 mg kg-1 exhibited mild clinical signs. All sheep were successfully treated with sodium thiosulfate. On the second day, only the sheep that received 0.46 mg kg-1 and 0.34 mg kg-1 exhibited mild clinical signs and recovered spontaneously. The concentration of HCN in the wastewater was 71.69±2.19 μg mL-1 immediately after production, 30.56±2.45 μg mL-1 after 24 hours, and 24.25±1.28 μg mL-1 after 48 hours. The picric acid paper test was strongly positive 5 minutes after production; moderately positive 24 hours after production, and negative 48 hours after production. We conclude that cassava wastewater is highly toxic to sheep if ingested immediately after production, but rapidly loses toxicity in 24-48 hours.(AU)

O processamento dos tubérculos de Manihot esculenta (mandioca) produzem diferentes subprodutos, incluindo a manipueira, líquido que escorre das raízes da mandioca depois de ter sido mecanicamente prensada. A intoxicação por cianeto após a ingestão de manipueira tem sido relatada em ruminantes e suínos no Nordeste do Brasil. Com o objetivo de estudar sua toxicidade, administrou-se manipueira por via oral a seis ovelhas em doses de 0,99, 0,75, 0,70, 0,63 e 0,5 mg de peso corporal de ácido cianídrico kg-1, correspondendo a 14,2, 10,6, 9,8, 8,89 e 7,1 mL de manipueira kg-1 de peso corporal. No segundo dia, as ovelhas receberam um volume de manipueira que correspondeu a 0,46, 0,34, 0,31, 0,28 e 0,23 mg de HCN kg-1. Uma ovelha usada como controle recebeu 9,9 mL de água kg-1 de peso corporal. Ovelhas que receberam doses de 0,75 a 0,99 mg kg-1 de HCN no primeiro dia exibiram sinais clínicos graves de intoxicação e as ovelhas que receberam 0,63 e 0,5 mg kg-1 exibiram sinais clínicos leves. Todas as ovelhas foram tratadas com sucesso com tiossulfato de sódio. No segundo dia, apenas as ovelhas que receberam 0,46 mg kg-1 e 0,34 mg kg-1 apresentaram sinais clínicos leves e se recuperaram espontaneamente. A concentração de HCN na manipueira foi de 71,69 ± 2,19 μg mL-1 imediatamente após a produção, 30,56 ± 2,45 μg mL-1 após 24 horas e 24,25 ± 1,28 μg mL-1 após 48 horas. O teste de papel picrosódico foi fortemente positivo 5 minutos após a produção; moderadamente positivo 24 horas após a produção e negativo 48 horas após a produção. Concluímos que a manipueira é altamente tóxica para ovinos se ingeridas imediatamente após a produção, mas rapidamente perdem toxicidade em 24-48 horas.(AU)

La mitocondria en la medicina legal y forense / The Mitochondrion in legal and forensic medicine

Las mitocondrias son las organelas intracelulares encargadas de suministrar la mayor parte de la energía necesaria para la actividad celular. Actúan, por lo tanto, como centrales energéticas de la célula y sintetizan ATP a expensas de los sustratos metabólicos. La intoxicación con ácido cianhídrico inhibe estos mecanismos y las alteraciones en el funcionamiento del metabolismo mitocondrial de origen genético o congénito producen innumerables patologías. El conocimiento de las patologías y disfunción de las mitocondrias es de importancia para realizar correctamente el diagnóstico de las causas de muerte. El ADN mitocondrial es de suma importancia en la medicina legal y forense para la identificación de las personas.

Mitochondria are organelles in the cell cytoplasm which supply most of the energy needed for cellular activity. They behave as cell’s power plants and synthesize ATP using metabolic substrates. Intoxication with Hydrocyanic Acid inhibits the synthesis of ATP, generating alterations in the mitochondrial metabolism, either genetic or congenital. The consequences of those alterations are innumerables pathologies. Understanding the pathologies and malfunctions of mitochondria help us to make the right diagnostic about the cause of death. In forensic medicine, mitochondrial DNA is of paramount relevance to people identification.

Effects of DMAP, NaNO_2 and Co_2EDTA on Hemodynamics of Severely HCN-poisoned Dogs / 第三军医大学学报

Under anesthesia and artificial respiration, all the dogs were injected with HCN 8 mg/kg intravenously. 2 minutes after HCN injection, 4-dimethylaminophenol( DM -AP) 3.2mg/kg,sodium nitrite(NaNO2)20 mg/kg,or dicobalt edetate(Co2EDTA) 15 mg/kg was given intravenously to different animals respectively. The changes of hemodynamics of the dogs were observed before and after the administration of the 3 HCN antidotes.It was found that intravenous injection of HCN rapidly induced a progressive decrease of heart rate(HR),stroke index(SI), cardiac index (CI),mean aortic pressure (MAP),left ventricular pressure(LVP) and ?dp/dtmax and a persistent increase of total peripheral vascular resistance (TPVR) and mean pulmonary arterial pressure (MPAP). If not treated,the dogs would died subsquently 4-9.5 minutes after HCN injection because of cardiac failure.2 to 8 minutes after DMAP administration, CI, MAP, LVP and?dp/dtmax increased markedly,and TPVR and MPAP would recover a little later. 4-6minutes after NaNO2 administration, ?dp/dtmax increased markedly, and CI, MAP, LVP, TPVR and MPAP returned to the normal. 6 minutes after Co2EDTA administration, MAP elevated markedly, LVP and?dp/dtmax returued to the normal, and C1, TPVR and MPAP would recover a little later. When observation was made again one hour after treatment, there was a remarkable decrease of blood pressure in NaNO2 and Co2EDTA treated animals and a slight decrease of blood pressure in DMAP treated ones.The conclusions based on the results are as follows:1. The ability of DMAP to restore the circulatory functions after HCN poisoning is more rapid and powerful than that of Co2EDTA or NaNO2.2. The cardiovascular functions restored by DMAP are more stable than those restored by the other two agents.3. DMAP and NaNO2 can rapidly reverse the HCN-iuduced damages on the cardiovascular functions, which may be a part of the anticyanide ability of these 2 drugs.