Oxytocin-induced changes in single cell K+ currents and smooth muscle contraction of guinea-pig gastric antrum

1997 ◽  
Vol 136 (5) ◽  
pp. 531-538 ◽  
Author(s):  
Dessislava B Duridanova ◽  
Milena D Nedelcheva ◽  
Hristo S Gagov
Keyword(s):  
Smooth Muscle ◽  
Cell Membrane ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Gastric Antrum ◽  
Dependent Manner ◽  
Response Curves ◽  
Dose Dependent ◽  
In Cells

Abstract To study the effects of oxytocin on both spontaneous phasic contractions and K+ outward currents (IK) of the so-called 'non-target' smooth muscle cells, physiological concentrations of oxytocin ranging between 10−12 mol/l and 10−8 mol/l were applied to smooth muscle preparations and single voltage-clamped cells isolated from the circular layer of the guinea-pig gastric antrum. Oxytocin (10−12mol/l to 10−8 mol/l) suppressed, in a dose-dependent manner, the tetrodotoxin- and atropine-resistant spontaneous phasic contractions and shifted rightward the dose–response curves of 10−7 mol/l charybdotoxin and 10−3mol/l BaCl2. In cells with preloaded intracellular Ca2+ stores, oxytocin (10−12 mol/l to 10−9 mol/l) caused a dose-dependent activation of the charybdotoxin-blockable non-inactivating component of IK (IK(s1)) of single voltage-clamped cells, which was accompanied by hyperpolarization of the cell membranes. 8Lys-vasopressin and 8arg-vasopressin failed to mimic the effects of oxytocin on both contraction and K+ currents. Further, the oxytocin-induced activation of IK(s1) was effectively antagonized by 5× 10−8 mol/l U-73122 or 5× 10−6 mol/l 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (inhibitors of the cell membrane phospholipase C), as well as by intracellularly applied heparin (selective inhibitor of inositol-1,4,5-trisphosphate (IP3)-induced Ca2+ release channels). In cells incubated in the absence of Ca2+ entry throughout the study, oxytocin (10−9 mol/l) caused a slight and transient increase of IK(s1) amplitudes. Neither ryanodine (10−6 mol/l nor cyclopiazonic acid (10−6 mol/l) were able to restore the IK-activating effect of oxytocin in these cells. The data obtained suggest (i) that selective oxytocin receptors are present on the membranes of guinea-pig antral smooth muscle cells, (ii) that the oxytocin-related relaxation may result from the activation of Ca2+-sensitive K+ conductivity via activation of IP3-induced release of Ca from the submembrane located cisternae of the sarcoplasmic reticulum Ca2+ stores and (iii) in turn, this evokes a non-inactivating component of IK, hyperpolarizing the cell membrane. European Journal of Endocrinology 136 531–538

Receptors on smooth muscle cells: characterization by contraction and specific antagonists

1982 ◽  
Vol 242 (4) ◽  
pp. G400-G407 ◽  
Author(s):  
K. N. Bitar ◽  
G. M. Makhlouf
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Low Doses ◽  
Response Curves ◽  
High Affinity ◽  
Gastric Smooth Muscle ◽  
Dose Dependent ◽  
Cck Receptor Antagonists

Smooth muscle cells were isolated from the stomach of the guinea pig, and the kinetics, stoichiometry, and specificity of contraction in response to the C-terminal octapeptides of cholecystokinin (CCK-OP), gastrin-17, and acetylcholine were examined. All three agonists elicited dose-dependent peak contraction that did not depend on the presence of extra-cellular calcium. The potencies of CCK-OP and gastrin-17 were equal (D50, 10(-11) M) and 10 times greater than the potency of acetylcholine (D50, 10(-10) M). A combination of low doses of acetylcholine and CCK-OP was synergistic; however, its effect did not exceed the maximal responses to either agonists alone or to high extracellular concentrations of calcium. The specificity of the receptors was established by the use of atropine and the two CCK-receptor antagonists dibutyryl cGMP and proglumide. The span of the dose-response curves was wide, suggesting the existence of receptor heterogeneity. It is concluded that gastric smooth muscle cells of the guinea pig possess distinct, high-affinity receptors for CCK-gastrin and acetylcholine; the receptors mediate contraction that is not immediately dependent on the presence of extracellular calcium.

Smooth muscle cells from guinea pig stomach possess high-affinity galanin receptors that mediate relaxation

1994 ◽  
Vol 266 (5) ◽  
pp. G839-G845 ◽  
Author(s):  
Z. F. Gu ◽  
T. K. Pradhan ◽  
D. H. Coy ◽  
R. T. Jensen
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Maximal Effect ◽  
Dependent Manner ◽  
High Affinity ◽  
Gastric Smooth Muscle ◽  
Guinea Pig Stomach ◽  
Galanin Receptors

Galanin-like immunoactivity occurs in nerves and plexi in muscle layers throughout gastrointestinal tract including the stomach. Galanin can affect gastric emptying and contraction or relaxation of gastric muscle in different species. The aim of this study was to investigate the direct effect of galanin on dispersed gastric smooth muscle cells and to characterize any galanin receptors that mediated any effect. Dispersed gastric smooth muscle cells were prepared from guinea pig stomach by collagenase digestion. Porcine galanin (p-galanin; 1 microM) did not stimulate contraction when present alone; however, p-galanin (1 microM) inhibited carbachol-induced contraction with a half-maximal effect at 7 nM. p-Galanin (1 microM) increased cellular adenosine 3',5'-cyclic monophosphate (cAMP) content by 10 s and caused a maximal increase of 80% over basal. 125I-galanin (porcine) bound to dispersed cells in a time- and temperature-dependent manner. Binding was saturable, reversible, and specific. Binding of 125I-galanin was inhibited almost equally by porcine and rat galanin (Ki = 6-8 nM) but was not inhibited by the galanin-associated peptide [preprogalanin-(108-123)]. The fragment galanin-(1-16) was equally potent to rat galanin; however, the fragment galanin-(9-29) was 56-fold less potent (Ki = 370 nM). Computer analysis demonstrated there were two binding sites for p-galanin on gastric smooth muscle cells, a high-affinity site (Kd = 2.6 nM) with low capacity (Bmax = 175 fmol/mg protein) and a low-affinity site (Kd = 150 nM) with large capacity (Bmax = 3,611 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Magnesium reduces calcification in bovine vascular smooth muscle cells in a dose-dependent manner

2011 ◽  
Vol 27 (2) ◽  
pp. 514-521 ◽  
Author(s):  
F. Kircelli ◽  
M. E. Peter ◽  
E. Sevinc Ok ◽  
F. G. Celenk ◽  
M. Yilmaz ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Dose Dependent

scholarly journals Panax notoginsengSaponins Attenuate Phenotype Switching of Vascular Smooth Muscle Cells Induced by Notch3 Silencing

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Nan Liu ◽  
Dazhi Shan ◽  
Ying Li ◽  
Hui Chen ◽  
Yonghong Gao ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Panax Notoginseng ◽  
Muscle Cells ◽  
Phenotypic Switching ◽  
Dependent Manner ◽  
Phenotype Switching ◽  
Dose Dependent

Panax notoginsengsaponins (PNS) could maintain vascular smooth muscle cells (VSMCs) in stable phenotypes so as to keep blood vessel elasticity as well as prevent failing in endovascular treatment with stent. Downregulation of Notch3 expression in VSMCs could influence the phenotype of VSMCs under pathologic status. However, whether PNS is able to attenuate the Notch3 silencing induced phenotype switching of VSMCs remains poorly understood. Primary human VSMCs were transfected with a plasmid containing a small interfering RNA (siRNA) against Notch3 and then exposed to different doses of PNS. The control groups included cells not receiving any treatment and cells transfected with a control siRNA. Phenotypic switching was evaluated by observing cell morphology with confocal microscopy, as well as examiningα-SM-actin, SM22α, and OPN using Western blot. Downregulated Notch3 with a siRNA induced apparent phenotype switching, as reflected by morphologic changes, decreased expression ofα-SM-actin and SM22αand increased expression of OPN. These changes were inhibited by PNS in a dose-dependent manner. The phenotype switching of VSMCs induced by Notch3 knockdown could be inhibited by PNS in a dose-dependent manner. Our study provided new evidence for searching effective drug for amending stability of atherosclerotic disease.

Cellular mechanisms of vasopressin and endothelin to mobilize [Mg2+]i in vascular smooth muscle cells

1992 ◽  
Vol 263 (4) ◽  
pp. C873-C878 ◽  
Author(s):  
K. Okada ◽  
S. Ishikawa ◽  
T. Saito
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Peak Level ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Cellular Mechanisms ◽  
Indicator Dye ◽  
Dose Dependent

The present study was undertaken to examine the effects of arginine vasopressin (AVP) and endothelin-1 (ET-1) on cytosolic free Mg2+ ([Mg2+]i) in cultured rat vascular smooth muscle cells (VSMC). [Mg2+]i was measured using the fluorescence indicator dye mag-fura-2. AVP and ET-1 at a concentration of 1 x 10(-9) M or higher induced the mobilization of [Mg2+]i and cytosolic free Ca2+ ([Ca2+]i) in a dose-dependent manner in rat VSMC. Atrial natriuretic peptide and sodium nitroprusside producing cellular guanosine 3',5'-cyclic monophosphate did not affect [Mg2+]i and [Ca2+]i. A diterpene activator of adenylate cyclase, forskolin, also did not alter [Mg2+]i and [Ca2+]i. The removal of extracellular Mg2+ enhanced the AVP-mobilized [Ca2+]i and did not change the AVP-mobilized [Mg2+]i. The Ca(2+)-free and nominally Mg2+/Ca(2+)-free states decreased the AVP-mobilized [Mg2+]i and [Ca2+]i. The Na(+)-free state enhanced the sustained, but not peak, level of the AVP-mobilized [Mg2+]i. These results indicate that AVP and ET-1 mobilize [Mg2+]i mediated through their intracellular second messenger [Ca2+]i and independent of extracellular Mg2+. Also, an increase in [Mg2+]i is indicated to stimulate the Na(+)-Mg2+ exchange to increase cellular Mg2+ efflux.

Abstract 523: Acetylation of Cyclophilin A in Response to Oxidative Stress Enhances Its Expression and Secretion

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Nwe Nwe Soe ◽  
Mark Sowden ◽  
Bradford C Berk
Keyword(s):  
Oxidative Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Time Dependent ◽  
Dependent Manner ◽  
Ang Ii ◽  
Aortic Smooth Muscle ◽  
Dose Dependent ◽  
Cypa Expression

Objective: Cyclophilin A (CyPA) is a Secreted OXidative stress-induced Factor (SOXF) secreted by cardiovascular cells in response to Angiotensin II (Ang II) and reactive oxygen species (ROS). Extracellular CyPA is a proinflammatory mediator that regulates vascular remodeling, abdominal aortic aneurysm, atherosclerosis and cardiac hypertrophy. Post-translational modification of CyPA by acetylation in response to ROS has been described. Moreover, acetylation of CyPA is important in HIV pathogenesis. The mechanism and regulation of CyPA acetylation as well as its role in cardiovascular diseases are currently unknown. We hypothesized that Ang II regulates oxidative stress-induced CyPA acetylation that alters its expression and/or secretion in vascular smooth muscle cells. Methods and results: Ang II (1μM) increased acetylation of CyPA (Acyl-CyPA) in a time dependent manner, with a peak at 8hr (3.5±0.6 fold increase) in rat aortic smooth muscle cells (RASMC) as shown by Western blot. Mouse aortic smooth muscle cells from mice lacking CyPA (CyPA-/-) and wild type controls (WT) confirmed that Ang II induced acetylation reactivity coincided exactly with CyPA reactivity. In AT1R and CyPA cotransfected HeLa cells, Ang II increased Acyl-CyPA in a time dependent manner consistent with that in RASMC. The ROS scavengers Tiron or N-acetylcysteine significantly inhibited Ang II induced Acyl-CyPA in a dose dependent manner in RASMC. Ang II-induced CyPA acetylation was enhanced by 2 hr pretreatment with histone deacetylase inhibitor trichostatin (TSA) or sirtinol in a dose dependent manner. Similarly, Ang II-induced CyPA secretion was enhanced by pretreatment with TSA (1μM) in a time dependent manner. Moreover, acetyltransferase p300 and PCAF (p300/CBP-asociated factor) inhibitor anacardic acid (6-nonadecyl salicylic acid) dramatically inhibited CyPA expression, and Ang II induced Acyl-CyPA in a dose dependent manner. Conclusion: These results suggest that Ang II-induced CyPA acetylation is oxidative stress dependent, and that acetylation enhanced CyPA expression and secretion. Detailed mechanistic studies of the regulation of CyPA acetylation will help to identify a future therapeutic target for CyPA regulated cardiovascular diseases.

Motilin receptors on isolated gastric smooth muscle cells

1988 ◽  
Vol 254 (2) ◽  
pp. G210-G216 ◽  
Author(s):  
D. S. Louie ◽  
C. Owyang
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Dose Response ◽  
Contractile Response ◽  
Muscle Cells ◽  
Maximal Response ◽  
Gastric Smooth Muscle ◽  
Substance P Antagonist ◽  
Dose Dependent

Motilin has a stimulating effect on gastrointestinal motility. The mechanism of its action is not known. Direct and neuronal effects have been postulated. To determine if receptors are present on smooth muscle cells we investigated the effect of synthetic porcine motilin and its interaction with acetylcholine on isolated guinea pig gastric smooth muscle cells. Motilin elicited a dose-dependent contraction of gastric smooth muscle cells. Minimal (8.3 +/- 1.3%) and maximal (33.9 +/- 2.4%) responses were observed at 10(-12) and 10(-6) M, respectively. The ED50 of motilin was 10(-9) M. Acetylcholine also elicited a dose-response muscle contraction with a maximal response observed at 10(-7) M. Atropine (10(-7) M) completely inhibited the maximal response to acetylcholine but did not have any effect on the contractile response to motilin. In addition, dibutyryl guanosine 3',5'-cyclic monophosphate (10(-3) M) and substance P antagonist, spantide (10(-4) M), also did not inhibit the action of motilin. Acetylcholine (10(-11) M) shifted the dose-response curve of motilin to the left by 1.5 log units. The maximal response to the combination of motilin (10(-6) M) and acetylcholine (10(-11) M) was 32 +/- 3.2%, which was similar to the maximal response to motilin alone. It is concluded that distinct motilin and muscarinic receptors are present on guinea pig gastric smooth muscle cells. The interaction between motilin and acetylcholine is additive and not potentiative.

Receptors for mammalian tachykinins on isolated intestinal smooth muscle cells

1985 ◽  
Vol 249 (4) ◽  
pp. G533-G538
Author(s):  
J. C. Souquet ◽  
J. R. Grider ◽  
K. N. Bitar ◽  
G. M. Makhlouf
Keyword(s):  
Smooth Muscle ◽  
Substance P ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Rank Order ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Receptor Subtype ◽  
Response Curves ◽  
Isolated Cells

The existence of receptors for three mammalian tachykinins, substance P (SP), substance K (SK), and neuromedin K (NK), was examined in smooth muscle cells, isolated separately from the longitudinal and circular muscle layers of guinea pig ileum. Tachykinin receptors capable of mediating contraction were present in muscle cells from both layers. The receptors were selectively blocked by the tachykinin antagonist [D-Pro2, D-Trp7,9]substance P but not by muscarinic, gastrin/cholecystokinin, or opiate antagonists (0.3 nM atropine, 1 mM proglumide, and 0.3 nM naloxone, respectively). The rank order of potency of tachykinins in causing contraction, NK greater than SP greater than SK, was similar in both muscle cell types. The results obtained in isolated muscle cells were closely paralleled by results obtained in intact muscle strips; the main difference was the greater sensitivity of isolated cells to tachykinin agonists (250-fold) and antagonist (210-fold). The inhibitory dissociation constant (Ki) of [D-Pro2, D-Trp7,9]substance P estimated from the displacement of dose-response curves (muscle cells) or from Schild plots (muscle strips) differed minimally or not at all, when either SP or SK was used as agonist, consistent with interaction of the two peptides with the same receptor subtype. The notion of a single receptor subtype in ileal muscle cells of the guinea pig was further supported by the occurrence of complete cross-desensitization between SP and SK in muscle strips.

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