Antioxidative and Anti-Inflammatory Activities of Rosebud Extracts of Newly Crossbred Roses

Oxidative stress and inflammation are basic pathogenic factors involved in tissue injury and pain, as well as acute and chronic diseases. Since long-term uses of synthetic steroids and non-steroidal anti-inflammatory drugs (NSAIDs) cause severe adverse effects, novel effective materials with minimal side effects are required. In this study, polyphenol content and antioxidative activity of rosebud extracts from 24 newly crossbred Korean roses were analyzed. Among them, Pretty Velvet rosebud extract (PVRE) was found to contain high polyphenols and to show in vitro antioxidative and anti-inflammatory activities. In RAW 264.7 cells stimulated with lipopolysaccharide (LPS), PVRE down-regulated mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and thereby decreased nitric oxide (NO) and prostaglandin E₂ (PGE₂) production. In a subcutaneous air-pouch inflammation model, treatment with PVRE decreased λ-carrageenan-induced tissue exudation, infiltration of inflammatory cells, and inflammatory cytokines such as tumor necrosis factor-α and interleukin-1β concentrations, as achieved with dexamethasone (a representative steroid). Notably, PVRE also inhibited PGE₂, similar to dexamethasone and indomethacin (a representative NSAID). The anti-inflammatory effects of PVRE were confirmed by microscopic findings, attenuating tissue erythema, edema, and inflammatory cell infiltration. These results indicate that PVRE exhibits dual (steroid- and NSAID-like) anti-inflammatory activities by blocking both the iNOS-NO and COX-2-PG pathways, and that PVRE could be a potential candidate as an anti-inflammatory material for diverse tissue injuries.

Ginseng Seed Oil Inhibits the Growth of Estrogen Receptor-positive Breast Cancer Cells

BACKGROUND/AIM

Although ginseng seed oil (GSO) appears to have various roles in the body, its anti-cancer effect has not been investigated. Tamoxifen is widely used to treat estrogen receptor-positive (ER+) breast cancer but shows adverse effects with drug resistance. This study investigated the effect of GSO in ER+ breast cancer cell growth.

MATERIALS AND METHODS

Cell viability assays, western blots and Annexin V staining were conducted to examine cell viability and apoptosis. The synergistic effect of tamoxifen in combination with GSO or oleic acid (OA) was determined.

RESULTS

GSO and OA caused apoptosis of MCF-7 ER+ breast cancer cells and had synergistic effects with tamoxifen in inhibiting tamoxifen-resistant MCF-7 (MCF-7^TAMR) ER+ breast cancer cell growth.

CONCLUSION

GSO may block ER+ breast cancer recurrence in combination with tamoxifen.

Implementing health promotion activities using community-engaged approaches in Asian American faith-based organizations in New York City and New Jersey

Faith-based organizations (FBOs) (e.g., churches, mosques, and gurdwaras) can play a vital role in health promotion. The Racial and Ethnic Approaches to Community Health for Asian Americans (REACH FAR) Project is implementing a multi-level and evidence-based health promotion and hypertension (HTN) control program in faith-based organizations serving Asian American (AA) communities (Bangladeshi, Filipino, Korean, Asian Indian) across multiple denominations (Christian, Muslim, and Sikh) in New York/New Jersey (NY/NJ). This paper presents baseline results and describes the cultural adaptation and implementation process of the REACH FAR program across diverse FBOs and religious denominations serving AA subgroups. Working with 12 FBOs, informed by implementation research and guided by a cultural adaptation framework and community-engaged approaches, REACH FAR strategies included (1) implementing healthy food policies for communal meals and (2) delivering a culturally-linguistically adapted HTN management coaching program. Using the Ecological Validity Model (EVM), the program was culturally adapted across congregation and faith settings. Baseline measures include (i) Congregant surveys assessing social norms and diet (n = 946), (ii) HTN participant program surveys (n = 725), (iii) FBO environmental strategy checklists (n = 13), and (iv) community partner in-depth interviews assessing project feasibility (n = 5). We describe the adaptation process and baseline assessments of FBOs. In year 1, we reached 3790 (nutritional strategies) and 725 (HTN program) via AA FBO sites. Most AA FBOs lack nutrition policies and present prime opportunities for evidence-based multi-level interventions. REACH FAR presents a promising health promotion implementation program that may result in significant community reach.

Barley grass extract causes apoptosis of cancer cells by increasing intracellular reactive oxygen species production

Cancer remains a leading cause of mortality worldwide, therefore food products are being investigated for potential prevention or treatment strategies. The ingredient, barley grass extract (Hordeum vulgare L.; Bex) is used to prevent or ameliorate various types of disease. In cancer, Bex has been revealed to inhibit tumor growth. However, its effect on cancer cells is yet to be clearly defined. In the present study, the effect of Bex on cancer cell growth was investigated. Bex inhibited the viabilities of breast and prostate cancer cells according to the results of MTT assays. Accordingly, Bex caused apoptosis, which was confirmed by Annexin V staining and western blot analysis for poly (ADP-ribose) polymerase and caspases. Furthermore, Bex increased the intracellular levels of reactive oxygen species (ROS), and N-acetyl-L-cystein blocked Bex-induced apoptosis. Therefore, the study demonstrated that Bex causes apoptosis of breast and prostate cancer cells by increasing intracellular ROS levels.

Inhibitory effects of Acorus calamus extracts on mast cell-dependent anaphylactic reactions using mast cell and mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Acorus calamus Linn. (Araceae) is a traditional herbal plant used for centuries to treat various allergic symptoms including asthma and bronchitis.

AIM OF THE STUDY

The present study was focused to provide a pharmacological basis for the traditional use of Acorus calamus in allergic symptoms using the mast cell-dependent anaphylactic reactions in in vitro and in vivo models.

MATERIALS AND METHODS

Cell viabilities were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Dinitrophenyl-human serum albumin (DNP-HSA) induced β-hexosaminidase and interleukin (IL)-4 productions in IgE-sensitized rat basophilic leukaemia (RBL-2H3) cells were measured by enzymatic assay and enzyme-linked immunosorbent assay (ELISA). Passive cutaneous anaphylaxis (PCA) reaction mouse model was implemented for in vivo studies.

RESULTS

Hot water (HW), butylene glycol (BG), hexane (HE) and steam distilled (SD) extracts of Acorus calamus showed different cytoxicity levels evaluated in RBL-2H3 cells. Sub-toxic doses of HW extract suppressed the β-hexosaminidase secretion and IL-4 production significantly and dose dependently in DNP-HSA induced IgE-sensitized RBL-2H3 cells compared to other extracts of Acorus calamus. Further, in vivo studies also revealed that the HW extract significantly inhibited the PCA reaction in mouse compared to the normal control group.

CONCLUSION

HW extract of Acorus calamus most effectively inhibited degranulation and IL-4 secretion in DNP-HSA-stimulated RBL-2H3 cells and also reduced the mast cell-mediated PCA reaction in mouse, providing a therapeutic evidence for its traditional use in ameliorating allergic reactions.

Anti-inflammatory and anti-allergic effects of Agrimonia pilosa Ledeb extract on murine cell lines and OVA-induced airway inflammation

ETHNOPHARMACOLOGICAL EVIDENCE

Agrimonia pilosa Ledeb (Rosaceae, AP) has long been used as a traditional medicine in Korea and other Asian countries to treat various diseases.

AIM OF THE STUDY

In the present study, the anti-inflammatory and anti-allergic effects of AP extract in in vitro cell lines and in vivo mouse model of inflammation and the molecular mechanisms involved were reported.

MATERIALS AND METHODS

Using Raw 264.7 murine macrophages the effects of methanol extract of AP in lipopolysaccharide (LPS)-induced production of inflammatory mediators were measured. Further IgE-DNP-induced interleukin (IL)-4 production and degranulation in RBL-2H3 rat basophilic cell lines was also estimated. To investigate the anti-asthmatic effect of AP in vivo, airway inflammation in ovalbumin (OVA)-induced mouse model was used.

RESULTS

AP attenuated the production of inflammatory mediators such as NO, PGE(2) and pro-inflammatory cytokines in LPS-induced Raw 264.7 cells. Further, AP inhibited IL-4 production and degranulation in IgE-DNP-induced RBL-2H3 cells. Furthermore, AP attenuated the infiltration of immune cells into lung, cytokines production in broncho-alveolar lavage fluid (BALF) and airway-hyperresponsiveness (AHR) on OVA-induced mouse model of inflammation.

CONCLUSION

Our results showed that AP attenuated the activation of macrophages, basophils, and inhibited the OVA-induced airway inflammation. The molecular mechanisms leading to AP's potent anti-inflammatory and anti-allergic effects might be through regulation of TRIF-dependent and Syk-PLCγ/AKT signaling pathways, suggesting that AP may provide a valuable therapeutic strategy in treating various inflammatory diseases including asthma.

Detection of 1,4-dihydroxy-2-naphthoic Acid from commercial makgeolli products

To support beneficial effects of makgeolli for human health, we investigated for the presence of 1,4-dihydroxy-2-naphthoic acid (DHNA), a bifidogenic growth stimulator (BGS), from commercial makgeolli products. Among eleven makgeolli products (A∼K), four showed positive peaks for DHNA in high performance liquid chromatography analysis. Makgeolli product A in particular contained the highest concentration of DHNA (0.44 ppm), as confirmed by liquid chromatography-mass spectrometry. Furthermore, BGS activity of the makgeolli product A was higher than those of products in which DHNA was not detected. These results indicate that makgeolli can be a good source for DHNA and that DHNA-enriched makgeolli could be developed by modifying manufacturing procedures and controlling its microbiota.

Oxidative modification of ferritin induced by hydrogen peroxide

Excess free iron generates oxidative stress that may contribute to the pathogenesis of various causes of neurodegenerative diseases. In this study, we assessed the modification of ferritin induced by H(2)O(2). When ferritin was incubated with H(2)O(2), the degradation of ferritin L-chain increased with the H(2)O(2) concentration whereas ferritin H-chain was remained. Free radical scavengers, azide, thiourea, and N-acetyl-(L)-cysteine suppressed the H(2)O(2)-mediated ferritin modification. The iron specific chelator, deferoxamine, effectively prevented H(2)O(2)-mediated ferritin degradation in modified ferritin. The release of iron ions from ferritin was increased in H(2)O(2) concentration-dependent manner. The present results suggest that free radicals may play a role in the modification and iron releasing of ferritin by H(2)O(2). It is assumed that oxidative damage of ferritin by H(2)O(2) may induce the increase of iron content in cells and subsequently lead to the deleterious condition.

Preliminary results of the luna aneurysm embolization system in a rabbit model: a new intrasaccular aneurysm occlusion device

BACKGROUND AND PURPOSE

Recent advances in endovascular devices have been aimed at providing high density, mesh-like metallic materials across the aneurysm neck, in place of coil technology. Therefore our aim was to report the in vivo preclinical performance of a self-expanding intrasaccular embolization device.

MATERIALS AND METHODS

Elastase-induced aneurysms were created in 12 rabbits. Each aneurysm was embolized with a Luna AES. DSA was performed preimplantation; 5, 10, and 30 minutes postimplantation; and at 1 month in 12 rabbits and at 3 months in 8 rabbits. Early postimplantation intra-aneurysmal flow was graded as unchanged, moderately diminished, or completely absent. One- and 3-month DSAs were graded by using a 3-point scale (complete, near-complete, or incomplete occlusion). Aneurysms were harvested for gross and microscopic histologic evaluation at 1 month (n = 4) and at 3 months (n = 8). Tissues within the aneurysm dome and across the aneurysm neck were assessed by using HE staining.

RESULTS

Ten (83%) of 12 aneurysms demonstrated complete cessation of flow within 30 minutes of device implantation. At 1-month follow-up, 10 (83%) of 12 aneurysms were completely occluded. At 3 months, 7 of 8 (88%) aneurysms remained completely occluded. One-month gross examination in 4 rabbits demonstrated that membranous tissue completely covered the device in 3 subjects (75%). Microscopic examination showed that 3 aneurysms had loose connective tissue filling the aneurysm cavity. Three-month gross and microscopic examinations demonstrated membranous tissue completely covering the device, loose connective tissue filling the aneurysm cavity, and neointima formation crossing the aneurysm neck in 8 of 8 (100.0%) subjects.

CONCLUSIONS

The Luna AES achieved high rates of complete angiographic occlusion and showed promising histologic findings in the rabbit aneurysm model.

Antioxidative activities of white rose flower extract and pharmaceutical advantages of its hexane fraction via free radical scavenging effects

In this study, we determined the antioxidant activities of two different solvent fractions(butanol and hexane) obtained from white Rosa rugosa flowers by employing various assays such as 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and nitric oxide (NO) scavenging and inhibition activity in S-nitroso-N-acetylpenicillamine (SNAP) in the RAW264.7 model. In addition, more advanced antioxidant assays were conducted, including lipid peroxidation, hydroxyl radical-mediated oxidation, DNA fragmentation, apoptosis, and cell growth. The results revealed that the hexane fraction, which contained a significant amount of polyphenols and volatile components, had excellent antioxidant potency and could scavenge free radicals of DPPH and ABTS. Interestingly, the hexane fraction inhibited lipid peroxidation to almost the same degree as a chemical antioxidant. In the NO assay, the hexane fraction effectively scavenged free radicals at all dose ranges and is expected to inhibit NO production in mammalian cells. The hexane fraction effectively prevented oxidative damage, which was induced by Cu2+/H2O2, to target proteins at lower concentrations (>1 μg·mL–1). The DNA fragmentation and the cell-level assays suggest that the hexane fraction may play a crucial role in inhibiting peroxynitrite and H2O2 attack. Based on the findings described in this study, the hexane fraction holds promise for use as a novel pharmaceutical antioxidant.

Coil Knotting during Endovascular Coil Embolization for Ruptured MCA Aneurysm. A Case Report

SUMMARY

Complications during coil embolization of cerebral aneurysms include thromboembolic events, hemorrhagic complications related to procedural aneurysmal rupture and parent vessel perforation, and coil-related complications. The present report describes a rare coil-related complication involving spontaneous coil knotting.

A double catheter technique for elongated middle cerebral artery bifurcation aneurysm. A case report

SUMMARY

We report a case of an elongated middle cerebral artery bifurcation aneurysm which was managed using an endovascular double catheter technique. After positioning two microcatheters, one at the distal dome and the other at the proximal dome, two coils were subsequently deployed through each microcatheter.We created a proximal supporting coil frame using one microcatheter and preserved the parent artery, and then deposited subsequent packing coils at the distal aneurysm sac region using the other microcatheter. The proximal framing coils did not detach prior to obtaining satisfactory aneurysm packing through the distally positioned microcatheter. This approach allowed for the proximal coil to be withdrawn if there was any evidence of the proximal coil frame changing shape or of parent artery protrusion. This double microcatheter technique provided safe and effective treatment of an elongated middle cerebral artery bifurcation aneurysm.

Mechanisms of acetylcholine-induced vasorelaxation in high K+-stimulated rabbit renal arteries

To characterize the mechanisms of acetylcholine (ACh)-induced vasorelaxation in rabbit renal arteries precontracted with high K+ (100 mM), muscle tension and cytosolic free Ca2+ concentration ([Ca2+]i) were measured simultaneously in the fura-2-loaded arterial strips. In the artery with endothelium, high K+ increased both [Ca2+]i and muscle tension. Addition of ACh (10 microM) during high-K+ induced contraction significantly relaxed the muscle and induced additional increase in [Ca2+]i. In the presence of NG-nitro-L-arginine (L-NAME, 0.1 mM). ACh increased [Ca2+]i without relaxing the muscle. In the artery without endothelium, high K+ increased both [Ca2+]i and muscle tension although ACh was ineffective, suggesting that ACh acts selectively on endothelium to increase [Ca2+]i. 4-DAMP (10 nM) or atropine (0.1 microM) abolished the ACh-induced increase in [Ca2+]i and relaxation. However, pirenzepine (0.1 microM), AF-DX 116 (1 microM) and tropicamide (1 microM) were ineffective. The ACh-induced increase of [Ca2+li and vasorelaxation was significantly reduced by 3 microM gadolinium, 10 microM lanthanum or 10 microM SKF 96365. These results suggest that, in rabbit renal artery, ACh-evoked relaxation of 100 mM K+-induced contractions is mediated by the release of endothelial NO. ACh may stimulates the M3 subtype of muscarinic receptor in the endothelial cells, resulting in the opening of the nonselective cation channels followed by an increase of [Ca2+]i and stimulation of NO synthase.

Mechanisms of NO-resistant relaxation induced by acetylcholine in rabbit renal arteries

The effects of K+ channel blockers and P2Y receptor agonist/antagonist on the vasorelaxation mediated by endothelium-derived hyperpolarizing factor (EDHF) were investigated in the rabbit renal artery. Acetylcholine (ACh, 1 nM-10 microM) induced endothelium-dependent relaxation of arterial rings precontracted with norepinephrine (NE, 1 microM) in a concentration-dependent manner. NG-nitro-L-arginine (L-NAME. 0.1 mM), an inhibitor of NO synthase, partially inhibited the ACh-induced endothelium-dependent relaxation. The ACh-induced relaxation was only partially inhibited by L-NAME whereas combined addition of L-NAME and 30 mM KCl completely inhibited the relaxation. The ACh-induced relaxation observed in the presence of L-NAME was significantly reduced by a combination of iberiotoxin (0.1 microM) and apamin (1 microM), and almost completely blocked by 4-aminopyridine (5 mM). The ACh-induced relaxation was antagonized by P2Y receptor antagonist, cibacron blue (10 and 100 microM) in a concentration-dependent manner. Furthermore, ADPbetaS, a potent P2Y agonist, induced the endothelium-dependent relaxation, and this relaxation was markedly reduced by either the combination of iberiotoxin and apamin or by cibacron blue alone. In conclusion, ACh may activate the release of ATP from endothelial cells which in turn activates a P2Y receptor on the endothelial cells followed by a release of EDHF, resulting in a vasorelaxation via a mechanism that involves activation of both the voltage-gated K+ channels and the Ca2+-activated K+ channels. EY WORDS: ATP, K+ channel, rabbit renal artery.

NO donor sodium nitroprusside inhibits excitation-contraction coupling in guinea pig taenia coli

In guinea pig taenia coli, the nitric oxide (NO) donor sodium nitroprusside (SNP, 1 microM) reduced the carbachol-stimulated increases in muscle force in parallel with a decrease in intracellular Ca(2+) concentration ([Ca(2+)](i)). A decrease in the myosin light chain phosphorylation was also observed that was closely correlated with the decrease in [Ca(2+)](i). With the patch-clamp technique, 10 microM SNP decreased the peak Ba(2+) current, and this effect was blocked by an inhibitor of soluble guanylate cyclase. Carbachol (10 microM) induced an inward current, and this effect was markedly inhibited by SNP. SNP markedly increased the depolarization-activated outward K(+) currents, and this current was completely blocked by 0.3 micorM iberiotoxin. SNP (1 microM) significantly increased cGMP content without changing cAMP content. Decreased Ca(2+) sensitivity by SNP of contractile elements was not prominent in the permeabilized taenia, which was consistent with the [Ca(2+)](i)-force relationship in the intact tissue. These results suggest that SNP inhibits myosin light chain phosphorylation and smooth muscle contraction stimulated by carbachol, mainly by decreasing [Ca(2+)](i), which resulted from the combination of the inhibition of voltage-dependent Ca(2+) channels, the inhibition of nonselective cation currents, and the activation of Ca(2+)-activated K(+) currents.

The involvement of K+ channels and the possible pathway of EDHF in the rabbit femoral artery

Experiments were designed to characterize the cellular mechanisms of action of endothelium-derived vasodilator substances in the rabbit femoral artery. Acetylcholine (ACh, 10(-8)-10(-5) M) induced a concentration-dependent relaxation of isolated endothelium-intact arterial rings precontracted with norepinephrine (NE, 10(-6) M). The ACh-induced response was abolished by the removal of endothelium. NG-nitro-L-arginine (L-NAME, 10(-4) M), an inhibitor of NO synthase, partially inhibited ACh-induced endothelium-dependent relaxation, whereas indomethacin (10(-5) M) showed no effect on ACh-induced relaxation. 25 mM KCl partially inhibited ACh-induced relaxation by shifting the concentration-response curve and abolished the response when combined with L-NAME and NE. In the presence of L-NAME, ACh-induced relaxation was unaffected by glibenclamide (10(-5) M) but significantly reduced by apamin (10(-6) M), and almost completely blocked by tetraethylammonium (TEA, 10(-3) M), iberiotoxin (10(-7) M) and 4-aminopyridine (4-AP, 5 x 10(-3) M). The cytochrome P450 inhibitors, 7-ethoxyresorufin (7-ER, 10(-5) M) and miconazole (10(-5) M) also significantly inhibited ACh-induced relaxation. Ouabain (10(-6) M), an inhibitor of Na+, K(+)-ATPase, or K(+)-free solution, also significantly inhibited ACh-induced relaxation. ACh-induced relaxation was not significantly inhibited by 18-alpha-glycyrrhetinic acid (18 alpha-GA, 10(-4) M). These results of this study indicate that ACh-induced endothelium-dependent relaxation of the rabbit femoral artery occurs via a mechanism that involves activation of Na+, K(+)-ATPase and/or activation of both the voltage-gated K+ channel (Kv) and the large-conductance, Ca(2+)-activated K+ channel (BKCa). The results further suggest that EDHF released by ACh may be a cytochrome P450 product.

Position paper of the American Council on Science and Health: lead and human health

The potential human health risk of lead in the environment remains a topic of current debate and concern. Given sufficient exposure, lead can exert severe and chronic health effects. Today, due to successful efforts to reduce the commercial use of lead and control its release to the environment, lead "poisoning" is uncommon in our society. Blood-lead levels among the U.S. population, including those of children, have decreased dramatically over the past decade and according to current surveillance programs continue to decline. Because lead poisoning among children is no longer as prevalent as it once was, the focus has shifted to the long-term effects lead may exert on the intellectual development of children. Continued toxicological and epidemiological research will expand the understanding of this important facet of the lead issue. Trace levels of lead in consumer products remain a low health risk to humans, despite the fear and uncertainty which often accompany such concerns. Future efforts to reduce lead exposure should be aimed at high-risk groups which include the socioeconomically disadvantaged and certain minority sectors of the population. Through educational programs, improvement in personal hygiene practices, and abatement of lead-containing paint (when warranted), blood lead levels should continue to decline, reducing the health risk to lead in the environment.

Isoproterenol changes the relationship between cytosolic Ca2+ and contraction in guinea pig taenia caecum

To determine the role of beta-adrenoceptors in the regulation of intestinal smooth muscle, the action of isoproterenol (ISO) on cytoplasmic Ca2+ level ([Ca2+]cyt) and mechanical activity in the isolated guinea pig taenia caecum was examined. Spontaneous changes in [Ca2+]cyt and contraction were inhibited by ISO (0.1-1 microM) without changing resting [Ca2+]cyt. ISO more strongly inhibited the histamine-induced contraction than the high K(+)-induced contraction. ISO inhibited muscle tension more strongly than [Ca2+]cyt stimulated by high K+ and thus shifted the [Ca2+]cyt-tension curve to the lower-right. In the muscle stimulated by histamine, on the other hand, ISO inhibited both [Ca2+]cyt and tension. Salbutamol, a beta 2-selective agonist, showed similar effects as ISO on spontaneous, high K(+)- and histamine-stimulated [Ca2+]cyt and tension. Stimulation of beta-adrenoceptors by ISO increased cyclic AMP content without changing cyclic GMP content. These results suggest that activation of beta 2-adrenoceptors by ISO inhibits the contractions by two mechanisms of action: decrease in Ca2+ sensitivity of contractile elements in the muscle stimulated by K(+)-depolarization and decrease in [Ca2+]cyt in the muscle stimulated by histamine. These effects may be mediated by cyclic AMP.

Membrane potential and current responses to neurotensin in the longitudinal muscle of the rectum of the fowl

1. The effects of neurotensin (NT) on membrane potential and membrane current of the longitudinal smooth muscle of chicken rectum were investigated by intracellular recording and whole-cell voltage clamp. 2. NT (3 nM-1.2 microM), when applied via the bathing medium, produced a concentration-dependent membrane depolarization with an EC50 of 18 +/- 2 nM (n = 7) which was accompanied by an increase in the membrane conductance. The effect was biphasic: an initial, rapid depolarization reached a peak within 2-3 min and then declined to a lower but still elevated level which was sustained until washout. 3. Excitatory junction potentials (e.j.ps), which were non-adrenergic non-cholinergic (NANC) in nature, were decreased in amplitude and total duration in the presence of NT (0.6 microM). The depression of the e.j.p. was due mainly to the reduction of the membrane resistance. 4. When NT was applied locally by means of pressure ejection from a micropipette containing NT, some cells responded with a membrane depolarization and some failed to respond, whereas e.j.ps could invariably be elicited from all of them. 5. In single muscle cells enzymatically isolated from the muscle and dialyzed under voltage clamp at -50 mV with a CsCl-rich solution, NT (5 or 10 microM) produced an inward current. NT-induced inward currents were obtained with inclusion of 10 mM EGTA in the pipette solution and their reversal potential was around 0 mV. In cells dialyzed under voltage clamp at 0 mV with a KCl-rich solution, NT (5 microM) produced a brief outward current followed by abolition of spontaneous transient outward currents.6. The present results suggest that the membrane depolarization, which may arise from activation of non-selective cation channels, and release of calcium from internal stores produced by neurotensin are responsible for its contractile activity in the longitudinal smooth muscle of chicken rectum. Further, the depolarizing effect may provide support for the involvement of NT in the NANC transmission in this preparation.

Changes in cytosolic CA2+ and contraction induced by various stimulants and relaxants in canine tracheal smooth muscle

Effects of stimulants and relaxants on the cytosolic Ca2+ level [(Ca2+]cyt) and contraction were examined in isolated canine tracheal smooth muscle. High K+ and carbachol induced a sustained increase in [Ca2+]cyt and muscle tension. Cumulative addition of KCl induced a graded increase in [Ca2+]cyt and muscle tension. Cumulative addition of carbachol induced greater contraction than high K+ at a given [Ca2+]cyt 12-Deoxyphorbol 13-isobutyrate (DPB) (50 nmol/l) induced a small sustained contraction with little effect on [Ca2+]cyt. A higher concentration (1 mumol/l) of DPB induced a larger sustained contraction with a decrease in [Ca2+]cyt. DPB (50 nmol/l) potentiated the KCl-induced contraction without or with only a small additional increase in [Ca2+]cyt. By contrast, 1 mumol/l DPB potentiated the high-K(+)-induced contraction with a decrease in [Ca2+]cyt. Addition of 50 nmol/l or 1 mumol/l DPB in the presence of carbachol inhibited both [Ca2+]cyt and muscle tension. Verapamil, isoprenaline and forskolin did not change or slightly decreased [Ca2+]cyt and muscle tension in resting trachea. Verapamil inhibited the contraction and [Ca2+]cyt stimulated by high K+ and carbachol. Isoprenaline and forskolin inhibited the high-K(+)-induced contraction without changing [Ca2+]cyt, whereas these inhibitors inhibited carbachol-induced contraction with a relatively small decrease in [Ca2+]cyt. These results suggest that (a) sustained contractions induced by high K+ and carbachol are due to the sustained increase in [Ca2+]cyt, (b) carbachol increases the sensitivity of contractile elements to Ca2+, and (c) isoprenaline and forskolin inhibit the contraction by the decrease in [Ca2+]cyt and also by the decrease in the sensitivity of contractile elements to Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of endothelin on the mechanical activity and cytosolic calcium level of various types of smooth muscle

1. Effects of porcine/human endothelin (endothelin-1), a novel vasoconstrictor peptide, on various smooth muscles were examined. 2. In rat aorta, endothelin (1 pM-30nM) induced contraction in a concentration-dependent manner. Removal of endothelium shifted the concentration-response curve to the left. When added during the sustained contraction induced by 0.1 microM noradrenaline, endothelin (1 nM) induced a relaxation that was inhibited by removing endothelium or by methylene blue. 3. In rat aorta without endothelium, endothelin (1-30 nM) increased cytosolic Ca2+ level [( Ca2+]cyt) followed by contraction. Endothelin induced less contraction than high K+ at a given [Ca2+] cyt when the concentration of endothelin was lower (1-3nm) and/or during the early phase of the contraction (less than 10 min). In contrast, endothelin induced a greater contraction than KCl after prolonged exposure to high concentrations (greater than 10 nM). 4. The increase in [Ca2+]cyt due to endothelin was strongly inhibited by 10 microM verapamil or 0.3 microM nicardipine although muscle contraction was only partially inhibited. 5.In Ca2+ -free solution, endothelin (30 nM) induced a transient increase in [Ca2+] cyt and a slow increase in muscle tension. After a prolonged incubation in Ca2+-free solution, endothelin (30 nM) still induced a slow increase in tension without changing [Ca2+]cyt. This contraction was inhibited by 1 microM sodium nitropusside or 10 microM forskolin. 6. In canine trachea and guinea-pig uterus, endothelin (30 nM) induced sustained contraction with an increase in [Ca2+]cyt. In the absence of external Ca2+, endothelin (30 nM) induced a sustained contraction in canine trachea without changing [Ca2+]cyt. In guinea-pig vas deferens, taenia caeci and ileal longitudinal muscle, endothelin induced small increases in [Ca2+]cyt and tension. 7. In permeabilized smooth muscles, endothelin (30 nM) did not change the muscle tone. 8. These results suggest that endothelin acts on the endothelium and increases the synthesis or release of endothelin-derived relaxing factor (EDRF). These results also suggest that endothelin acts directly on smooth muscle and increases [Ca2+]cyt by releasing Ca2+ from sites and increasing Ca2+ influx through the verapamil- and 1,4-dihydropyridine-sensitive pathway. Endothelin seems to decrease Ca2+ -sensitivity of contractile elements at lower concentrations and/or during the early phase of the contraction, whereas it increases Ca2+ -sensitivity at higher concentrations during the sustained phase of the contraction. Furthermore, endothelin induces a contraction that is not dependent on [Ca2+]cyt.

Possible role of plasma neurotensin in regulating the excitatory neural control of the rectum of the fowl

Effects of neurotensin (NT) applied via the blood vessel on the responses to stimulation of Remak's nerve (RNS) were investigated in the chicken isolated and perfused rectums. NT (5 ng-2 micrograms/ml) produced a concentration-dependent inhibition of the constituent contraction but not relaxation of the responses to RNS. In addition, high concentrations of NT (over 80 ng/ml) produced a contraction of the rectal muscle. Propranolol, a beta-adrenoceptor blocking agent, and guanethidine, an adrenergic neurone blocking agent, were able to reduce the inhibitory effect of NT on the response to RNS while potentiating the contractile effect of NT on the rectal muscle. NT (0.1 and 1 microgram/ml), like norepinephrine, decreased the flow rate of perfusate from the isolated rectum which was perfused at a constant pressure. Guanethidine enhanced norepinephrine-induced vasoconstriction, and phentolamine, an alpha-adrenoceptor blocking agent, plus propranolol was able to abolish it. Either of these prior applications resulted in a small but significant reduction of NT-induced vasoconstriction. These findings suggest that NT in plasma may function as a circulating hormone to exhibit an inhibitory action on the excitatory neural input to the rectum in the chicken, and that catecholamine release from adrenergic nerve terminals by NT may account for some but not all of the activity.

Effects of prolonged exposure to alpha,beta-methylene ATP on non-adrenergic, non-cholinergic excitatory transmission in the rectum of the chicken

1. Effects of prolonged exposure to alpha,beta-methylene ATP (alpha,beta-Me ATP) on contractions and excitatory junction potentials (e.j.ps) evoked by non-adrenergic, non-cholinergic (NANC) excitatory nerve stimulation have been investigated in the chicken isolated rectum and longitudinal muscle strip from chicken rectum pretreated with atropine (0.5 microM), methysergide (2 microM) and pyrilamine (3 microM). 2. Alpha,beta-Me ATP (20 nM-4 microM) caused a rapid rise in tension of the longitudinal muscle of the isolated rectum preparation which returned to the baseline levels after a few minutes. The magnitude of the contractile response to NANC nerve stimulation was reduced after exposure to the drug. The inhibitory effect was related to the drug concentration; at 4 microM the nerve-mediated contraction was abolished and frequently converted to a relaxation. 3. Adenosine 5'-triphosphate (ATP, 100 microM), bovine neurotensin (2.5 nM) and K+-rich solutions (30 nM and 60 nM) all produced a transient contraction of the isolated rectum preparation. The exposure to alpha,beta-Me ATP (0.2 and 4 microM) also rendered the preparation less sensitive to these stimulant substances. 4. Alpha,beta-Me ATP (0.2 and 4 microM) caused a membrane depolarization in cells of the longitudinal muscle strip. The depolarization reached a peak within 2-3 min after application and then decayed to a steady level that was still more positive than the baseline level. The electrotonic potentials were reduced in amplitude to 44 +/- 8% (n = 7) of the normal amplitude if measured at the peak depolarization produced with 0.2 microM alpha,beta-Me ATP, and to 62 +/- 10% (n = 7) if measured at the steady-state depolarization. With 4 microM, the corresponding percentages were 33 +/- 7% (n = 8) and 55 +/- 7% (n = 8), indicating a decrease in membrane resistance. 5. The e.j.ps in response to field stimulation of the intramural nerves and Remak's nerve stimulation were decreased in amplitude and duration during exposure to alpha,beta-Me ATP (0.2 and 4 microM). 6. The smooth muscle cells regained normal membrane resistance and sensitivity to ATP on washout of alpha,beta-Me ATP (4 microM) more rapidly than the responses to NANC nerve stimulation. 7. It can be argued from the results that the suppression by alpha,beta-Me ATP of the contraction and e.j.p. evoked by NANC nerve stimulation in the chicken rectum, unlike the mammalian preparation described previously, is due mainly to a change in the electrical properties of the membrane of the smooth muscle cells, rather than being due, or only partly due, to desensitization of the purine receptor.