Effect of Phlorofucofuroeckol A and Dieckol Extracted from Ecklonia cava on Noise-induced Hearing Loss in a Mouse Model

One of the well-known causes of hearing loss is noise. Approximately 31.1% of Americans between the ages of 20 and 69 years (61.1 million people) have high-frequency hearing loss associated with noise exposure. In addition, recurrent noise exposure can accelerate age-related hearing loss. Phlorofucofuroeckol A (PFF-A) and dieckol, polyphenols extracted from the brown alga Ecklonia cava, are potent antioxidant agents. In this study, we investigated the effect of PFF-A and dieckol on the consequences of noise exposure in mice. In 1,1-diphenyl-2-picrylhydrazyl assay, dieckol and PFF-A both showed significant radical-scavenging activity. The mice were exposed to 115 dB SPL of noise one single time for 2 h. Auditory brainstem response(ABR) threshold shifts 4 h after 4 kHz noise exposure in mice that received dieckol were significantly lower than those in the saline with noise group. The high-PFF-A group showed a lower threshold shift at click and 16 kHz 1 day after noise exposure than the control group. The high-PFF-A group also showed higher hair cell survival than in the control at 3 days after exposure in the apical turn. These results suggest that noise-induced hair cell damage in cochlear and the ABR threshold shift can be alleviated by dieckol and PFF-A in the mouse. Derivatives of these compounds may be applied to individuals who are inevitably exposed to noise, contributing to the prevention of noise-induced hearing loss with a low probability of adverse effects.

Eckol from Ecklonia cava Suppresses Immunoglobulin E-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis in Mice

Eckol, a precursor compound belonging to the dibenzo-1,4-dioxin class of phlorotannins, is a phloroglucinol derivative that exerts various activities. In the present study, we investigated the antiallergic effects of eckol isolated from the marine brown algae, Ecklonia cava using immunoglobulin E (IgE)/bovine serum albumin (BSA)-stimulated mouse bone marrow-derived cultured mast cells (BMCMC) and a mouse model of anaphylaxis. Eckol inhibited IgE/BSA-induced BMCMC degranulation by reducing β-hexosaminidase release. A flow cytometric analysis revealed that eckol decreases FcεRI expression on cell surface and IgE binding to the FcεRI in BMCMC. Moreover, eckol suppressed the production of the cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 and the chemokine, thymus activation-regulated chemokine (TARC) by downregulating, IκB-α degradation and NF-κB nuclear translocation. Furthermore, it attenuated the passive cutaneous anaphylactic reaction induced by IgE/BSA-stimulation in the ear of BALB/c mice. These results suggest that eckol is a potential therapeutic candidate for the prevention and treatment of allergic disorders.

Ishige okamurae Extract and Its Constituent Ishophloroglucin A Attenuated In Vitro and In Vivo High Glucose-Induced Angiogenesis

Diabetes is associated with vascular complications, such as impaired wound healing and accelerated vascular growth. The different clinical manifestations, such as retinopathy and nephropathy, reveal the severity of enhanced vascular growth known as angiogenesis. This study was performed to evaluate the effects of an extract of Ishige okamurae (IO) and its constituent, Ishophloroglucin A (IPA) on high glucose-induced angiogenesis. A transgenic zebrafish (flk:EGFP) embryo model was used to evaluate vessel growth. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), gap closure, transwell, and Matrigel® assays were used to analyze the proliferation, migration, and capillary formation of EA.hy926 cells. Moreover, protein expression were determined using western blotting. IO extract and IPA suppressed vessel formation in the transgenic zebrafish (flk:EGFP) embryo. IPA attenuated cell proliferation, cell migration, and capillary-like structure formation in high glucose-treated human vascular endothelial cells. Further, IPA down regulated the expression of high glucose-induced vascular endothelial growth factor receptor 2 (VEGFR-2) and downstream signaling molecule cascade. Overall, the IO extract and IPA exhibited anti-angiogenic effects against high glucose-induced angiogenesis, suggesting their potential for use as therapeutic agents in diabetes-related angiogenesis.

Characterizing Eckol as a Therapeutic Aid: A Systematic Review

The marine biosphere is a treasure trove of natural bioactive secondary metabolites and the richest source of structurally diverse and unique compounds, such as phlorotannins and halo-compounds, with high therapeutic potential. Eckol is a precursor compound representing the dibenzo-1,4-dioxin class of phlorotannins abundant in the Ecklonia species, which are marine brown algae having a ubiquitous distribution. In search of compounds having biological activity from macro algae during the past three decades, this particular compound has attracted massive attention for its multiple therapeutic properties and health benefits. Although several varieties of marine algae, seaweed, and phlorotannins have already been well scrutinized, eckol deserves a place of its own because of the therapeutic properties it possesses. The relevant information about this particular compound has not yet been collected in one place; therefore, this review focuses on its biological applications, including its potential health benefits and possible applications to restrain diseases leading to good health. The facts compiled in this review could contribute to novel insights into the functions of eckol and potentially enable its use in different uninvestigated fields.

Anti-Neuroinflammatory Property of Phlorotannins from Ecklonia cava on Aβ25-35-Induced Damage in PC12 Cells

Alzheimer disease (AD) is a neurodegenerative disorder characterized by excessive accumulation of amyloid-beta peptide (Aβ) and progressive loss of neurons. Therefore, the inhibition of Aβ-induced neurotoxicity is a potential therapeutic approach for the treatment of AD. Ecklonia cava is an edible brown seaweed, which has been recognized as a rich source of bioactive derivatives, mainly phlorotannins. In this study, phlorotannins including eckol, dieckol, 8,8'-bieckol were used as potential neuroprotective candidates for their anti-apoptotic and anti-inflammatory effects against Aβ25-35-induced damage in PC12 cells. Among the tested compounds, dieckol showed the highest effect in both suppressing intracellular oxidative stress and mitochondrial dysfunction and activation of caspase family. Three phlorotannins were found to inhibit TNF-α, IL-1β and PGE₂ production at the protein levels. These result showed that the anti-inflammatory properties of our compounds are related to the down-regulation of proinflammatory enzymes, iNOS and COX-2, through the negative regulation of the NF-κB pathway in Aβ25-35-stimulated PC12 cells. Especially, dieckol showed the strong anti-inflammatory effects via suppression of p38, ERK and JNK. However, 8,8'-bieckol markedly decreased the phosphorylation of p38 and JNK and eckol suppressed the activation of p38. Therefore, the results of this study indicated that dieckol from E. cava might be applied as a drug candidate for the development of new generation therapeutic agents against AD.

Protective Effect of Pyrogallol-Phloroglucinol-6,6-Bieckol from Ecklonia cava on Monocyte-Associated Vascular Dysfunction

Ecklonia cava (E. cava) can alleviate vascular dysfunction in diseases associated with poor circulation. E. cava contains various polyphenols with different functions, but few studies have compared the effects of these polyphenols. Here, we comparatively investigated four major compounds present in an ethanoic extract of E. cava. These four major compounds were isolated and their effects were examined on monocyte-associated vascular inflammation and dysfunctions. Pyrogallol-phloroglucinol-6,6-bieckol (PPB) significantly inhibited monocyte migration in vitro by reducing levels of inflammatory macrophage differentiation and of its related molecular factors. In addition, PPB protected against monocyte-associated endothelial cell death by increasing the phosphorylations of PI3K-AKT and AMPK, decreasing caspase levels, and reducing monocyte-associated vascular smooth muscle cell proliferation and migration by decreasing the phosphorylations of ERK and AKT. The results of this study show that four compounds were effective for reduction of monocyte-associated vascular inflammation and dysfunctions, but PPB might be more useful for the treatment of vascular dysfunction in diseases associated with poor circulation.

Protective Effect of Eckol against Acute Hepatic Injury Induced by Carbon Tetrachloride in Mice

Several in vitro studies have shown the potential hepatoprotective properties of eckol, a natural phlorotannin derived from the brown alga. However, the in vivo hepatoprotective potential of eckol has not been determined. In this study, we performed an in vivo study to investigate the protective effect of eckol and its possible mechanisms on the carbon tetrachloride (CCl₄)-induced acute liver injury model in mice. Results revealed that eckol pre-treatment at the dose of 0.5 and 1.0 mg/kg/day for 7 days significantly suppressed the CCl₄-induced increases of alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum and meliorated morphological liver injury. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) analysis showed that the number of positive apoptotic hepatocytes in the eckol-treated group was lower than that in the CCl₄ model group. Western blotting analysis also demonstrated the enhanced expression of bcl-2 and suppressed expression of cleaved caspase-3 by eckol. The CCl₄-induced oxidative stress in liver was significantly ameliorated by eckol, which was characterized by reduced malondialdehyde (MDA) formations, and enhanced superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and glutathione (GSH) content. Moreover, the CCl₄-induced elevations of pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were markedly suppressed in the eckol-treated group. However, eckol enhanced the level of IL-10, a potent anti-inflammatory cytokine, and recruited CD11c⁺ dendritic cells into the liver tissues of CCl₄-treated mice. These results indicated that eckol has the protective effect on CCl₄-induced acute liver injury via multiple mechanisms including anti-apoptosis, anti-oxidation, anti-inflammation and immune regulation.

The protective action of tocopherol and acetylsalicylic acid on the behavior of rats treated with dioxins

BACKGROUND

Dioxins contribute to neurological disorders in humans and animals, causing also neurological disorders in offspring during prenatal and postnatal periods. These compounds significantly affect the development of the central nervous system (CNS) structures, which results in behavioral changes. Tocopherol (TCP) and acetylsalicylic acid (ASA) may provide protective measures to reduce the inflammatory effects in the CNS associated with free radicals generated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), thus contributing to the reduction of the negative effects of dioxin.

OBJECTIVES

The main objective of this study was to determine the influence of dioxin on rats and their behavioral functions, and to ascertain whether a combined administration of TCP and ASA to rats treated with TCDD shows the possibility of potential protective effect on the functioning of the CNS.

MATERIAL AND METHODS

Experiments were performed on 75 female and 12 male Buffalo strain rats, which are offspring of females from particular study groups. TCDD was used in the experiments, TCP and ASA were administered orally every day for 3 weeks. Animals were subjected to behavioral testing: the tail and swimming tests.

RESULTS

During the observation of the offspring of both sexes born to females exposed to TCDD, males did not demonstrate any attempt to swim, whereas in females, the immobility time was significantly extended. Assessing the response times from the tail test in the animals treated with dioxins in relation to the control group, it was demonstrated that the response time was extended in the 3rd measurement in both females and males.

CONCLUSIONS

Dioxin is characterized by neurotoxic effect causing behavioral disorders associated with prolonged response times. The use of TCP after the administration of dioxins causes a significant reduction and improvement of reflex response times. In contrast, ASA reduces the reflex response times also in the offspring of females exposed to TCDD and ASA.

Phlorofucofuroeckol A isolated from Ecklonia cava alleviates postprandial hyperglycemia in diabetic mice

This study was designed to investigate whether phlorofucofuroeckol A inhibited α-glucosidase and α-amylase activities and alleviated postprandial hyperglycemia in diabetic mice. Phlorofucofuroeckol A that was isolated from Ecklonia cava (brown algae) demonstrated prominent inhibitory effects against α-glucosidase and α-amylase activities. The IC50 values of phlorofucofuroeckol A against α-glucosidase and α-amylase were 19.52 and 6.34μM, respectively. These inhibitory activities of phlorofucofuroeckol A were higher than those of acarbose, which was used as a positive control. Increases in postprandial blood glucose levels were significantly more suppressed in the group administered phlorofucofuroeckol A compared to the control group in both diabetic and normal mice. Moreover, the area under the curve was significantly lower after phlorofucofuroeckol A administration (2296 versus 2690mmolmin/l) in the diabetic mice. These results suggested that phlorofucofuroeckol A is a potent α-glucosidase inhibitor and can alleviate the postprandial hyperglycemia that is caused by starch.

Phlorotannins isolated from the edible brown alga Ecklonia stolonifera exert anti-adipogenic activity on 3T3-L1 adipocytes by downregulating C/EBPα and PPARγ

The dramatic increase in obesity-related diseases emphasizes the need to elucidate the cellular and molecular mechanisms underlying fat metabolism. Inhibition of adipocyte differentiation has been suggested to be an important strategy for preventing or treating obesity. In our previous study, we characterized an Ecklonia stolonifera extract and non-polar fractions thereof, including dichloromethane and ethyl acetate fractions. We showed that these fractions inhibited adipocyte differentiation and lipid formation/accumulation in 3T3-L1 preadipocytes, as assessed by Oil Red O staining. As part of our ongoing search for anti-obesity agents derived from E. stolonifera, in this work, we characterized five known phlorotannins, including phloroglucinol, eckol, dieckol, dioxinodehydroeckol, and phlorofucofuroeckol A, all of which were isolated from the active ethyl acetate fraction of E. stolonifera. We determined the chemical structures of these phlorotannins through comparisons of published nuclear magnetic resonance (NMR) spectral data. Furthermore, we screened these phlorotannins for their abilities to inhibit adipogenesis over a range of concentrations (12.5-100 μM). Of these five phlorotannins, phloroglucinol, eckol, and phlorofucofuroeckol A significantly concentration-dependently inhibited lipid accumulation in 3T3-L1 cells without affecting cell viability. In addition, the five isolated phlorotannins also significantly reduced the expression levels of several adipocyte marker genes, including proliferator activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), although they did so to different extents. These results suggest that the molecular weight of a phlorotannin is an important factor affecting its ability to inhibit adipocyte differentiation and modulate the expression levels of adipocyte marker genes.

Anti-inflammatory effect of ethanolic extract from Myagropsis myagroides on murine macrophages and mouse ear edema

BACKGROUND

This study aims to investigate anti-inflammatory effect of ethanolic extract of Myagropsis myagroides (EMM) in the lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages and the phorbol 12-myristate 13-acetate (PMA)-induced ear edema in mice, and to clarify its underlying molecular mechanisms.

METHODS

The levels of nitric oxide (NO), prostaglandin E2 (PGE2), and pro-inflammatory cytokines were measured by Griess assay and enzyme linked immunosorbent assay. The expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), mitogen-activated protein kinases (MAPKs), and Akt were measured using Western blotting. Nuclear translocation and transcriptional activation of nuclear factor-κB (NF-κB) were determined by immunocytochemistry and reporter gene assay, respectively. PMA-induced mouse ear edema was used as the animal model of inflammation. Anti-inflammatory compounds in EMM were isolated using high-performance liquid chromatography and identified by nuclear magnetic resonance.

RESULTS

EMM significantly inhibited the production of NO, PGE2, and pro-inflammatory cytokines in a dose-dependent manner and suppressed the expression of iNOS and COX-2 in LPS-stimulated RAW 264.7 cells. EMM strongly suppressed nuclear translocation of NF-κB by preventing degradation of inhibitor of κB-α as well as by inhibiting phosphorylation of Akt and MAPKs. EMM reduced ear edema in PMA-induced mice. One of the anti-inflammatory compounds in EMM was identified as 6,6'-bieckol.

CONCLUSIONS

These results suggest that the anti-inflammatory properties of EMM are associated with the down-regulation of iNOS, COX-2, and pro-inflammatory cytokines through the inhibition of NF-κB pathway in LPS-stimulated macrophages.

Dioxin is a promoter blocker, a promoter, and a net anticarcinogen

An ad hoc panel of dioxin experts convened by EPA's Science Advisory Board found the Agency's claim of cancer causation by dioxin unacceptable. This paper uses the very same two studies [Fingerhut (NIOSH) and Kociba] EPA relied upon to test the observations made in an unused third study [Bertazzi] to conclude that dioxin is (1) a promoter blocker of certain cancers, including all the cancers Agency scientists claimed dioxin promoted; (2) a promoter of some other cancers that EPA scientists failed to identify; and (3) a net anticarcinogen. Three independent total tumor reductions provide evidence of both cancer prevention and quantifiable risk reductions tied to specific dioxin levels. The author indirectly suggests a general cancer prevention treatment, even for cancers already initiated.

Enhancement of antitumour activity of etoposide by dihydropyridines on drug-sensitive and drug-resistant leukaemia in mice

We recently reported that six 1,4-dihydropyridine derivatives out of 57 screened effectively over-came vincristine (VCR)-resistance in VCR-resistant (P388/VCR) leukaemia-bearing mice when the dihydropyridines and VCR were administered intraperitoneally (i.p.). Furthermore, among the six dihydropyridine derivatives, two compounds, NK-250 and NK-252, most effectively overcame VCR-resistance while exhibiting relatively low calcium antagonistic activity and toxicity. In this study, we examined whether NK-250 and NK-252 could potentiate the antitumour activities of etoposide in mice with drug-sensitive (P388/S) or VCR-resistant (P388/VCR) leukaemia cells when the anticancer agents and tumour cells were administered by various routes. In both groups of mice inoculated i.p. with P388/S- and P388/VCR-leukaemia cells, the oral (p.o.) administration of NK-250 combined with i.p. or intravenously (i.v.) administration of etoposide (ip-po-ip trials and ip-po-iv trials) dramatically potentiated the antitumour activity of etoposide. Although etoposide alone was less effective in treating mice inoculated i.v. with P388/S- and P388/VCR-leukaemia cells, p.o. administration of NK-250 combined with i.p. or i.v. administration of etoposide (iv-po-ip trials and iv-po-iv trials) potentiated the antitumour activity of etoposide to similar levels as in treating mice inoculated i.p. with leukaemia cells. These 1,4-dihydropyridines were therefore highly effective in potentiating anticancer drugs against both drug-sensitive and drug-resistant tumours.

Characterization of MDL 73005EF as a 5-HT1A selective ligand and its effects in animal models of anxiety: comparison with buspirone, 8-OH-DPAT and diazepam

1. With radioligand binding techniques, MDL 73005 EF (8-[2-(2,3-dihydro-1,4-benzodioxin-2-yl-methylamino)ethyl]-8-az aspiro[4, 5]decane-7,9-dione methyl sulphonate) shows high affinity (pIC50 8.6) and selectivity (greater than 100 fold compared to other monoamine and benzodiazepine receptor sites) for the 5-hydroxytryptamine (5-HT)1A recognition site; it was both more potent and more selective than buspirone in this respect. 2. In rats pretreated with reserpine, 8-hydroxy-2-(di-n-propyl-amino) tetralin (8-OH-DPAT) induced forepaw treading and flat body posture; in the same model, MDL 73005EF and buspirone showed minimal agonist activity and at high doses MDL 73005EF inhibited responses to 8-OH-DPAT. 3. In rats trained to discriminate 8-OH-DPAT from saline in a drug discrimination paradigm, both MDL 73005EF and buspirone generalized dose-dependently and completely to the 8-OH-DPAT cue. 4. To define the anxiolytic potential of MDL 73005EF, it was examined in the elevated plus-maze test and in the water-lick conflict test in comparison with diazepam and buspirone. In both tests MDL 73005EF induced effects similar to those seen following diazepam. Buspirone had similar effects to both MDL 73005EF and diazepam in the water-lick conflict test but opposite effects in the elevated plus-maze. 8-OH-DPAT also had opposite effects in the elevated plus-maze test to MDL 73005EF and diazepam. 5. The anti-conflict effects of MDL 73005EF were reversed by low doses of the 5-HT1A receptor agonist, 8-OH-DPAT; those of buspirone were neither antagonised nor mimicked by 8-OH-DPAT. 6. These results suggest that an interaction with 5-HTIA receptors is the basis of the anxiolytic-like activity of MDL 73005EF. However, its mechanism of action is clearly different from that of buspirone, possibly reflecting a greater selectivity for the 5-HTlA receptors located presynaptically on central 5- hydroxytryptaminergic neurones.

[The Ca2+ reactivity and the subunit composition of myocardial actomyosin during the pyromecaine and pyrroxan treatment of experimental ischemia]

The treatment with pyromecaine and pyrroxan for 5 days was found to prevent disturbances of the physicochemical properties and the composition of the components of actomyosin complex of the rat heart left ventricle caused by experimental myocardial ischemia. Pyrroxan is able to change also the gene expression thereby leading to the appearance of a new isoform of myocardial myosin reminding by its characteristics the isoform of myosin of the rapidly contracting skeletal muscles.

Double-blind, placebo-controlled clinical evaluation of guaimesal in outpatients

One hundred and forty outpatients, males and females aged 14 to 70 years, with acute febrile bronchitis, afebrile chronic bronchitis, or flares of chronic bronchitis were treated for seven days with one soft gelatin capsule (500 mg) of guaimesal thrice daily or matching placebo. No other potentially interfering treatment (antibiotic, antipyretic, or anti-inflammatory) was administered concomitantly. Before and after treatment, vital capacity, residual volume, and maximum expiratory volume per second were measured and recorded. Both before treatment and after 2, 4, and 7 days of treatment, body temperature was measured and cough frequency and intensity as well as expectorate amount and fluidity were scored and recorded along with the total symptom score. At the end of treatment, the overall clinical efficacy was rated and recorded. Potential side effects were monitored by questioning the patients; general safety (laboratory tests) was not monitored. All data were analyzed according to multivariate, parametric, and nonparametric statistical methods and stratified by treatment, sex, age, and diagnosis. For each monitored symptom and sign, guaimesal exhibited a favorable effect which was significantly greater in extent and significantly faster in recovery rate than that associated with spontaneous recovery. Within two days from the start of therapy, fever, cough frequency and intensity, and expectorate fluidity had significantly improved. By the fourth day the expectorate amount had significantly decreased. Further improvement was noted at subsequent times of observation. After a week, according to the spirometric parameters, the respiratory function was restored to a considerable extent. Overall, 75.7% of the patients receiving guaimesal experienced complete or almost complete recovery within the period of observation. With placebo, occasional improvement was seen for cough intensity and for expectorate amount, and this improvement was significantly less in extent and significantly slower than that recorded with guaimesal. Overall, 8.6% of placebo-treated patients experienced a clinically detectable degree of recovery. The subjective tolerance of guaimesal was comparable to that of placebo in terms of both the frequency and the nature of the side effects. Mild, transient gastric effects were reported by 11.4% of patients receiving guaimesal and by 8.6% of patients receiving placebo. These effects did not require a variation of dose or specific treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Postischemic administration of idazoxan, an alpha-2 adrenergic receptor antagonist, decreases neuronal damage in the rat brain

The effect of an alpha-2 receptor antagonist, idazoxan, on ischemic neuronal damage in the hippocampus and neocortex was studied in rats following 10 min of forebrain ischemia. Idazoxan was given 0.1 mg/kg i.v. immediately after recirculation, followed by 48 h of continuous infusion at a rate of 10 micrograms/kg/min. A histopathological examination of the CA1 region of the dorsal hippocampus and neocortex from each hemisphere was made on paraffin-embedded sections following 7 days of survival. In ischemic animals receiving an infusion of saline, 71% of the neurons in the hippocampal CA1 region were degenerated. In contrast, in the idazoxan-treated animals only 31% of the neurons were irreversibly damaged (p less than 0.01). We conclude that postischemic administration of the alpha-2 antagonist idazoxan protects neurons against damage following cerebral ischemia. Rapid postischemic administration of alpha-2 adrenergic receptor antagonists could be an effective treatment after stroke and cardiac arrest.

Intracoronary alpha 2-adrenergic receptor blockade attenuates ischemia in conscious dogs during exercise

Studies on the role of alpha-adrenergic constrictor tone in the coronary vascular bed during ischemia were performed in dogs running on a treadmill. The animals were instrumented with a left ventricular pressure transducer, and regional systolic wall thickening (%WTh) was assessed by sonomicrometry in the anterior and posterior walls of the left ventricle. An intracoronary catheter was implanted chronically in the circumflex coronary artery, and a hydraulic cuff was placed proximally around the artery. After beta-adrenergic blockade with propranolol (0.8 mg/kg i.v.), acute stenosis of the coronary artery was performed during running in five dogs to induce severe regional myocardial dysfunction in the posterior wall. Intracoronary infusion of the selective alpha 2-adrenergic blocking agent idazoxan (80 micrograms/kg) improved %WTh in the ischemic region from 5.1 +/- 1.6 to 10.8 +/- 2.8% (p less than 0.05), without any significant effect on the anterior wall. Blood flow to the subendocardium of the posterior wall (radioactive microspheres) increased from 0.17 +/- 0.05 to 0.45 +/- 0.30 (ml/min)/g (p less than 0.05). It is concluded that in exercising dogs subjected to beta-adrenergic blockade, significant postjunctional alpha 2-adrenergic receptor-mediated coronary vasoconstriction exists, even during severe ischemia. Regional alpha 2-adrenergic receptor blockade can reduce regional ischemia and improve contractile function by attenuating exercise-induced sympathetic vasoconstriction in this conscious animal model.

[Effect of the sympatholytic pirroxan on catecholamine excretion in experimental tetanus]

Excretion of catecholamines and vanilylmandelic acid was studied in rabbits with tetanic intoxication. It was found that catecholamine excretion increases up to 173% in the initial stages of the disease and falls to 51% at the height of the disease whereas excretion of vanilylmandelic acid progressively decreases down to 40% against normal. Pirroxan (10 mg/kg a day) reduces excretion of catecholamines and vanilylmandelic acid by three times, concurrently producing a definite cholinolytic effect.