Enkephalin-induced inhibition of the isolated rat ileum is not blocked by naloxone

1981 ◽  
Vol 59 (8) ◽  
pp. 901-903 ◽  
Author(s):  
K. Nakatsu ◽  
E. Goldenberg ◽  
D. Penning ◽  
K. Jhamandas
Keyword(s):  
Dependent Manner ◽  
Narcotic Antagonist ◽  
Concentration Dependent Manner ◽  
Rat Ileum ◽  
Leucine Enkephalin ◽  
Isolated Rat

Both methionine- and leucine-enkephalin caused the isolated rat ileum to relax in a concentration-dependent manner; the EC50 values were in the order of 10−8 to 10−7 M. This isolated preparation was generally not sensitive to morphine. The enkephalin-induced inhibitions were not blocked by the classical narcotic antagonist, naloxone.

scholarly journals The effect of the aqueous and methanol fennel stem extracts (Foeniculum vulgare Miller) on isolated rat ileum contractility

2018 ◽  
Vol 75 (8) ◽  
pp. 809-814 ◽  
Author(s):  
Marija Gocmanac-Ignjatovic ◽  
Dusanka Kitic ◽  
Mirjana Radenkovic ◽  
Milica Kostic ◽  
Milica Milutinovic ◽  
...  
Keyword(s):  
Dependent Manner ◽  
Foeniculum Vulgare ◽  
Concentration Dependent Manner ◽  
Rat Ileum ◽  
Caffeoylquinic Acid ◽  
Dicaffeoylquinic Acid ◽  
Stem Extract ◽  
Spontaneous Contractions ◽  
Foeniculum Vulgare Miller ◽  
Isolated Rat

Background/Aim. The fennel (Foeniculum vulgare Miller, Apiaceae) has a long history of use as traditional herb medicine due to its carminative properties. The study was aimed to investigate the effects of aqueous and methanol fennel stem extracts on intestinal activity. Methods. Relaxant activity of aqueous and methanol fennel stem extracts was evaluated in vitro in three experimental models: spontaneous contraction, acetylcholine and potassium chloride (KCl)-induced contraction of an isolated rat ileum. The composition of aqueous and methanol fennel stem extracts was qualitatively analyzed using the high performance liquid chromatographic (HPLC) analysis. Results. In the presence of an aqueous fennel stem extract at a concentration of 3 mg/mL, the inhibition of the spontaneous contractions of isolated rat ileum was 35.05% ? 3.57%. In presence of a methanol fennel stem extract at the same concentration, the maximum reduction of the spontaneous contractions was 48.91% ? 6.31%. The extracts in a concentration- dependent manner significantly inhibited the acetylcholine and KCl induced contractions of the isolated rat ileum (p < 0.01). The following components were identified in fennel methanol stem extract: 3-caffeoylquinic acid, chlorogenic acid, 4-caffeoylquinic acid, 1,3-dicaffeoylquinic acid, rutin, miquelianin, quercetin heterosides, 1,5-dicaffeoylquinic acid, 1,4-dicaffeoylquinic acid, apigenin and rosmarinic acid. In an aqueous extract, their presence is found in trace amounts. Conclusion. The results of this study showed that the aqueous and methanol fennel stem extracts have spasmolytic effects on the intestinal smooth muscle and may be used for the control of intestinal motility.

Sarcolemmal cation channels and exchangers modify the increase in intracellular calcium in cardiomyocytes on inhibiting Na+-K+-ATPase

2007 ◽  
Vol 293 (1) ◽  
pp. H169-H181 ◽  
Author(s):  
Harjot K. Saini ◽  
Naranjan S. Dhalla
Keyword(s):  
Intracellular Calcium ◽  
Channel Blocker ◽  
Critical Role ◽  
Cation Channels ◽  
Dependent Manner ◽  
Additive Effects ◽  
Concentration Dependent Manner ◽  
Rat Cardiomyocytes ◽  
Induced Changes ◽  
Isolated Rat

Although inhibition of the sarcolemmal (SL) Na+-K+-ATPase is known to cause an increase in the intracellular concentration of Ca2+ ([Ca2+]i) by stimulating the SL Na+/Ca2+ exchanger (NCX), the involvement of other SL sites in inducing this increase in [Ca2+]i is not fully understood. Isolated rat cardiomyocytes were treated with or without different agents that modify Ca2+ movements by affecting various SL sites and were then exposed to ouabain. Ouabain was observed to increase the basal levels of both [Ca2+]i and intracellular Na+ concentration ([Na+]i) as well as to augment the KCl-induced increases in both [Ca2+]i and [Na+]i in a concentration-dependent manner. The ouabain-induced changes in [Na+]i and [Ca2+]i were attenuated by treatment with inhibitors of SL Na+/H+ exchanger and SL Na+ channels. Both the ouabain-induced increase in basal [Ca2+]i and augmentation of the KCl response were markedly decreased when cardiomyocytes were exposed to 0–10 mM Na+. Inhibitors of SL NCX depressed but decreasing extracellular Na+ from 105–35 mM augmented the ouabain-induced increase in basal [Ca2+]i and the KCl response. Not only was the increase in [Ca2+]i by ouabain dependent on the extracellular Ca2+ concentration, but it was also attenuated by inhibitors of SL L-type Ca2+ channels and store-operated Ca2+ channels (SOC). Unlike the SL L-type Ca2+-channel blocker, the blockers of SL Na+ channel and SL SOC, when used in combination with SL NCX inhibitor, showed additive effects in reducing the ouabain-induced increase in basal [Ca2+]i. These results support the view that in addition to SL NCX, SL L-type Ca2+ channels and SL SOC may be involved in raising [Ca2+]i on inhibition of the SL Na+-K+-ATPase by ouabain. Furthermore, both SL Na+/H+ exchanger and Na+ channels play a critical role in the ouabain-induced Ca2+ increase in cardiomyocytes.

Modification of intracellular calcium concentration in cardiomyocytes by inhibition of sarcolemmal Na+/H+ exchanger

2006 ◽  
Vol 291 (6) ◽  
pp. H2790-H2800 ◽  
Author(s):  
Harjot K. Saini ◽  
Naranjan S. Dhalla
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Extracellular Ph ◽  
The Other ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Rat Cardiomyocytes ◽  
Intracellular Ca ◽  
Isolated Rat

Although the Na+/H+ exchanger (NHE) is considered to be involved in regulation of intracellular Ca2+ concentration ([Ca2+]i) through the Na+/Ca2+ exchanger, the exact mechanisms of its participation in Ca2+ handling by cardiomyocytes are not fully understood. Isolated rat cardiomyocytes were treated with or without agents that are known to modify Ca2+ movements in cardiomyocytes and exposed to an NHE inhibitor, 5-( N-methyl- N-isobutyl)amiloride (MIA). [Ca2+]i in cardiomyocytes was measured spectrofluorometrically with fura 2-AM in the absence or presence of KCl, a depolarizing agent. MIA increased basal [Ca2+]i and augmented the KCl-induced increase in [Ca2+]i in a concentration-dependent manner. The MIA-induced increase in basal [Ca2+]i was unaffected by extracellular Ca2+, antagonists of the sarcolemmal (SL) L-type Ca2+ channel, and inhibitors of the SL Na+/Ca2+ exchanger, SL Ca2+ pump ATPase and mitochondrial Ca2+ uptake. However, the MIA-induced increase in basal [Ca2+]i was attenuated by inhibitors of SL Na+-K+-ATPase and sarcoplasmic reticulum (SR) Ca2+ transport. On the other hand, the MIA-mediated augmentation of the KCl response was dependent on extracellular Ca2+ concentration and attenuated by agents that inhibit SL L-type Ca2+ channels, the SL Na+/Ca2+ exchanger, SL Na+-K+-ATPase, and SR Ca2+ release channels and the SR Ca2+ pump. However, the effect of MIA on the KCl-induced increase in [Ca2+]i remained unaffected by treatment with inhibitors of SL Ca2+ pump ATPase and mitochondrial Ca2+ uptake. MIA and a decrease in extracellular pH lowered intracellular pH and increased basal [Ca2+]i, whereas a decrease in extracellular pH, in contrast to MIA, depressed the KCl-induced increase in [Ca2+]i in cardiomyocytes. These results suggest that NHE may be involved in regulation of [Ca2+]i and that MIA-induced increases in basal [Ca2+]i, as well as augmentation of the KCl-induced increase in [Ca2+]i, in cardiomyocytes are regulated differentially.

Up4A stimulates endothelium-independent contraction of isolated rat pulmonary artery

2008 ◽  
Vol 294 (4) ◽  
pp. L733-L738 ◽  
Author(s):  
Yu Gui ◽  
Michael P. Walsh ◽  
Vera Jankowski ◽  
Joachim Jankowski ◽  
Xi-Long Zheng
Keyword(s):  
Pulmonary Artery ◽  
Vascular Tone ◽  
Rho Kinase ◽  
P2y Receptors ◽  
Extracellular Nucleotides ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
P2x And P2y Receptors ◽  
Potent Vasoconstrictor ◽  
Isolated Rat

Extracellular nucleotides, such as ATP, UDP, and UTP, regulate pulmonary vascular tone through P2X and P2Y receptors. Recently, uridine adenosine tetraphosphate (Up4A) was reported as a novel endothelium-derived vasoconstrictive factor. Up4A contains both purine and pyrimidine moieties, which potentially activate P2X and P2Y receptors. The present study examined the effect of Up4A on contractility of isolated rat pulmonary artery. Up4A at 1–100 μM stimulated contraction in a concentration-dependent manner. Up4A was equipotent as UTP and UDP in the endothelium-denuded artery while much more effective than UTP and UDP in endothelium-intact preparations. The vasoconstrictor effect of Up4A was inhibited by suramin but not IP5I or desensitization of P2X receptors with α,β-methylene-ATP (α,β-Me-ATP). Up4A-induced contraction was also inhibited by pretreatment with thapsigargin, nitrendipine, or EGTA but unaffected by H1152. Furthermore, unlike ATP and UTP, Up4A did not induce relaxation of endothelium-intact preparations precontracted with phenylephrine. These results suggest that Up4A is a potent vasoconstrictor, but not a vasodilator, of the rat pulmonary artery. Up4A likely acts through a suramin-sensitive P2Y receptor. The contractile effect of Up4A involves the entry of extracellular Ca2+ and release of Ca2+ from intracellular stores but not Ca2+ sensitization via the RhoA/Rho kinase pathway. Up4A, therefore, potentially plays an important role in the regulation of pulmonary vascular tone.

Analysis of the Mechanisms Underlying the Vasorelaxant Action of Coptisine in Rat Aortic Rings

2012 ◽  
Vol 40 (02) ◽  
pp. 309-320 ◽  
Author(s):  
Li-Li Gong ◽  
Lian-Hua Fang ◽  
Hai-Lin Qin ◽  
Yang Lv ◽  
Guan-Hua Du
Keyword(s):  
Dependent Manner ◽  
Free Solution ◽  
Free Medium ◽  
Response Curves ◽  
Concentration Dependent Manner ◽  
Vasorelaxant Effect ◽  
Voltage Dependent ◽  
Endothelium Dependent Relaxation ◽  
External Calcium ◽  
Isolated Rat

The aim of the present study was to evaluate the vasorelaxant effects of coptisine and its possible mechanisms in isolated rat aortic rings. Coptisine was evaluated on isolated rat aortic rings precontracted with norepinephrine (NE) and KCl. The mechanisms were evaluated in the presence or absence of specific pharmacological inhibitors. Coptisine (1 ~ 200 μM) relaxed NE (1 μM) or KCl (60 mM) induced sustained contraction with pEC50 values of 4.49 ± 0.48 and 4.85 ± 0.57 in a concentration dependent manner. Pretreatment with coptisine (10, 50 or 100 μM) also inhibited concentration-response curves to NE and KCl. The vasorelaxant effect of coptisine was attenuated significantly by endothelium removal, and incubation with Nω-nitro-L-arginine methyl ester (L-NAME, 100 μM), methylene blue (10 μM) and indomethacin (5 μM) partially reduced the vasorelaxant effect of coptisine. In endothelium-denuded rings, the vasorelaxant effect of coptisine was reduced significantly by 4-aminopyridine (4-AP, 100 μM), but not glibenclamide (10 μM) ortetraethylammonium (TEA, 5 mM). Coptisine also reduced NE-induced transient contraction in Ca2+ -free solution, and inhibited contraction induced by increasing external calcium in Ca2+ -free medium plus 60 mM KCl. It was concluded that coptisine induced both endothelium-dependent and -independent relaxation in rat aortic rings. The NO-cGMP mediated pathway may be involved in the endothelium-dependent relaxation and in the activation of voltage-dependent K+ channels, contributing in part to the endothelium-independent relaxation bycoptisine. Coptisine also blocks extracellular Ca2+ influx by interacting with both voltage- and receptor-operated Ca2+ channels.

scholarly journals Inhibition of neural phospholipase D activity by aminoglycoside antibiotics

1991 ◽  
Vol 279 (1) ◽  
pp. 319-321 ◽  
Author(s):  
M Liscovitch ◽  
V Chalifa ◽  
M Danin ◽  
Y Eli
Keyword(s):  
Side Effects ◽  
Rat Brain ◽  
Phospholipase D ◽  
Aminoglycoside Antibiotics ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Brain Membranes ◽  
Rat Brain Membranes ◽  
Isolated Rat

The effects of aminoglycoside antibiotics on phospholipase D (PLD) activity were investigated in permeabilized NG108-15 cells and in isolated rat brain membranes. Neomycin inhibited guanosine 5′-[gamma-thio]triphosphate-stimulated PLD activity in digitonin-permeabilized NG108-15 cells in a concentration-dependent manner (50% inhibition at 100 microM). Neomycin similarly inhibited PLD activity present in rat brain membranes and assayed in vitro with [3H]phosphatidylcholine as substrate (50% inhibition at 65 microM). Other aminoglycosides tested (kanamycin, geneticin and streptomycin) were nearly equipotent inhibitors of rat brain PLD. These results indicate that aminoglycoside antibiotics inhibit phosphatidylcholine-PLD activity with comparable and sometimes greater potency than their well known inhibition of phosphoinositide-phospholipase C. The possibility that PLD inhibition could mediate some of the toxic side effects of aminoglycosides is suggested.

scholarly journals Relaxant activity of aqueous and ethanol extracts of parsley (Petroselinum crispum (Mill.) Nym. ex A.W. Hill, Apiaceae) on isolated ileum of rat

2010 ◽  
Vol 63 (7-8) ◽  
pp. 475-478 ◽  
Author(s):  
Suzana Brankovic ◽  
Dusanka Kitic ◽  
Mirjana Radenkovic ◽  
Vesna Ivetic ◽  
Slavimir Veljkovic ◽  
...  
Keyword(s):  
Aqueous Ethanol ◽  
Ethanol Extract ◽  
Albino Rats ◽  
Petroselinum Crispum ◽  
Organ Bath ◽  
Dependent Manner ◽  
Response Curves ◽  
Rat Ileum ◽  
Ethanol Extracts ◽  
Isolated Rat

Introduction. Parsley (Petroselinum crispum) is used in the traditional herbal medicine to treat intestinal disorders. The aim of this study was to examine the effect of aqueous and ethanol extracts of parsley on spontaneous and acetylcholine induced contractions on isolated rat ileum. Material and methods. Wistar albino rats (250-300g) were used in this study. The ileum portions were isolated out and cleaned off mesenteries. Preparations 2 cm long were mounted in 20 ml tissue baths containing Tyrode's solution maintained at 37?C and aerated with a mixture of 5% carbon dioxide in oxygen. In the first part of experiments, contractile responses to the aqueous (ethanol) extracts of parsley were recorded. In the second part, increasing concentrations of acetylcholine were added to the organ bath for a full concentration response curve and then concentration response curves were obtained after adding the aqueous (ethanol) extracts of parsley. Results and discussion. Our results showed that aqueous (62.22?7.15%) and ethanol (79.16?9.34%) extracts of parsley in dose dependent manner decreased the tonus of spontaneous contractions of isolated rat ileum. The aqueous (32.16?2.75%) and ethanol (53.96?4.86%) extracts of parsley reduced the acetylcholine induced contraction, the reduction was greater with ethanol extract than with the aqueous one. Conclusion. It can be concluded that the aqueous and ethanol extracts of parsley exert antispasmodic activity on rat ileum. The relaxant effect of ethanol extract was better comparing to aqueous extract of parsley.

Reversal of cholera toxin-induced secretion in rat ileum by luminal berberine

1981 ◽  
Vol 241 (3) ◽  
pp. G248-G252 ◽  
Author(s):  
E. A. Swabb ◽  
Y. H. Tai ◽  
L. Jordan
Keyword(s):  
Polyethylene Glycol ◽  
Cholera Toxin ◽  
Electrolyte Transport ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Berberine Hydrochloride ◽  
Rat Ileum ◽  
Normal Water ◽  
Electrolyte Secretion

The effect of luminal berberine hydrochloride concentration on cholera toxin-induced water and electrolyte secretion and on normal water and electrolyte transport was determined in vivo in the cannulated, perfused rat ileum using [14C]polyethylene glycol as a nonabsorbable marker. Berberine reduced the cholera toxin-induced secretion of water, Na, Cl, and calculated residual ion (primarily HCO3) in a concentration-dependent manner. The effect of berberine on cholera toxin-induced ileal secretion was evident 60-80 min after exposure and was reversed 60–80 min after removal of berberine from the perfusate. Mild changes in mucosal histology (villous tip edema) due to cholera toxin were also reversed by berberine. Berberine did not significantly alter normal ileal water and electrolyte transport.

Effects of atriopeptin III on isolated rat afferent and efferent arterioles

1991 ◽  
Vol 261 (6) ◽  
pp. F1102-F1109 ◽  
Author(s):  
D. M. Lanese ◽  
B. H. Yuan ◽  
S. A. Falk ◽  
J. D. Conger
Keyword(s):  
Angiotensin Ii ◽  
Lumen Diameter ◽  
Dependent Manner ◽  
Ang Ii ◽  
Concentration Dependent Manner ◽  
Isolated Rat ◽  
Rat Kidneys

The effects of atriopeptin III (AP III) on in vitro prepared afferent (AA) and efferent arterioles (EA) from rat kidneys were tested in a system in which lumen diameter could be measured. AP III (10(-13)-10(-7) M) had no effect on lumen diameter of AA that were not preconstricted. When AA were preconstricted with either angiotensin II (ANG II) or norepinephrine (NE), however, AP III increased lumen diameter in a concentration-dependent manner to the preconstriction baseline value. Maximal vasodilation occurred at 10(-10) M AP III. Unlike AA, EA constricted by 50% to 10(-10) M AP III further constricted EA that were pretreated with ANG II or NE. Dilation in ANG II-preconstricted AA to AP III was not inhibited by indomethacin. Constriction of EA to AP III was not altered by [Sar1-Ala8] ANG II, enalapril, OKY 046, or phentolamine. Results indicate that in isolated renal arterioles AP III dilates preconstricted AA but constricts EA that have either not been pretreated or have been preconstricted with other agonists. The effect of AP III on preconstricted AA does not require vasodilator prostaglandin mediation. The constrictor effect of AP III on EA is not dependent on angiotensin, thromboxane, or alpha-adrenergic mediation.

Modulation of cholinergic neurotransmission in airways by enkephalin

1985 ◽  
Vol 58 (3) ◽  
pp. 853-858 ◽  
Author(s):  
J. A. Russell ◽  
E. J. Simons
Keyword(s):  
Smooth Muscle ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Response Curves ◽  
Concentration Dependent Manner ◽  
Methionine Enkephalin ◽  
Leucine Enkephalin ◽  
Significant Difference ◽  
Before And After ◽  
Release Of Acetylcholine

We compared the effects of methionine enkephalin and leucine enkephalin on contractions of isolated canine tracheal smooth muscle strips induced by field electrical stimulation (ES) and exogenous acetylcholine (approximately 10(-5) M). Methionine and leucine enkephalin (10(-8) to 10(-5) M), when added at the peak of airway contractions induced by ES at 1 Hz, depressed the contractions in a concentration-dependent manner by a maximum of 95 and 99%, respectively. Acetylcholine-induced contractions of similar magnitude were depressed only 4% by methionine enkephalin and 12% by leucine enkephalin. Frequency-response curves (0.5–20 Hz) were also obtained before and after incubation of tracheal strips with 10(-5) M methionine and leucine enkephalin. Enkephalin depressed contractions induced by stimulation at 0.5 and 1 Hz by an average of 98 and 95%, respectively. The inhibitory effect of enkephalin progressively decreased at successively higher stimulus frequencies until at 20 Hz there was no significant difference between airway contractions obtained in the presence and absence of enkephalin. Naloxone (3 X 10(-5) M) antagonized the inhibitory effects of both enkephalins. We conclude that methionine and leucine enkephalins inhibit the release of acetylcholine from the postganglionic parasympathetic neurons that innervate airway smooth muscle.

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