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The action of L-ascorbic acid (AA) on the isolated rat stomach fundus and guinea pig ileum was studied. AA induced contractions of these organs and potentiated the effect of ACh and PGE2. The contractile effect of AA was potentiated by eserine and inhibited by atropine. Dose-response relations suggest a stimulatory effect of AA on the muscarinic receptor. 相似文献
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The effects of vitamin C and acetylcholine on the smooth muscle of rat stomach were compared after neomycin-induced blockade of phosphatidylinositol metabolism. The cumulative curves of dose-dependent responses showed a non-competitive antagonism between vitamin C and neomycin. On the other hand, the antagonism between acetylcholine and neomycin was of a mixed, competitive-non-competitive type. The results of the experiments suggest the conclusion that a normal metabolism of phosphatidylinositol controlling calcium transport into the cells is necessary for the stimulating effect of vitamin C on the contractions of the smooth muscles in the digestive tract. 相似文献
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Ruczyński Jarosław Konstański Zdzisław Korolkiewicz Roman Petrusewicz Jacek Rekowski Piotr 《International journal of peptide research and therapeutics》2002,9(2-3):91-99
Summary Galanin (GAL), a 29-amino-acid-residue neuropeptide, modulates gastric smooth muscles activity by interacting with specific
receptors. However due to the lack of specific antagonists in the gastrointestinal (GI) tract the actual level of GAL involvement
in GI motility remains largely unknown. In our studies we have performed structure-activity relationship studies of two porcine
galanin fragments, two chimeric galanin analogues and several 15-amino-acid-residue galanin analogues modified in positions
2, 3, 4, 6, 8 or 14, investigating their contractile action on rat isolated gastric fundus strips, employed as in vitro assay
of peptides activity. Thus we intended to characterize the molecular domains of GAL responsible for binding and activation
of GAL receptors in rat gastric smooth muscle cells. The data acquired in the course of our structure-activity relationship
studies suggest that both N-and C-terminal fragment of GAL molecule contribute towards the affinity and activity of GAL gastric
smooth muscle cell receptors. Moreover, we concluded that positions 2, 3, 4, 6, 8 and 14 in the amino acid sequence of GAL
may play important roles in binding and activation of GAL receptors in rat gastric smooth muscle cells.
Abbreviations: The symbols of the amino acids, peptides and their derivatives are in accordance with the 1983 Recommendations of the IUPAC-IUB
Joint Commission on Biochemical Nomenclature (Eur. J. Biochem.
138, 9 (1984)). Other symbols 相似文献
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Jarosaw Ruczyski Zdzisaw Konstaski Roman Korolkiewicz Jacek Petrusewicz Piotr Rekowski 《Letters in Peptide Science》2002,9(2-3):91-99
Galanin (GAL), a 29-amino-acid-residue neuropeptide, modulatesgastric smooth muscles activity by interacting with specific receptors. However due to the lack of specific antagonists in thegastrointestinal (GI) tract the actual level of GAL involvement in GI motility remains largely unknown. In our studies we have performed structure-activity relationship studies of two porcinegalanin fragments, two chimeric galanin analogues and several 15-amino-acid-residue galanin analogues modified in positions 2, 3, 4, 6, 8 or 14, investigating their contractile action on rat isolated gastric fundus strips, employed as in vitro assay of peptides activity. Thus we intended to characterize the moleculardomains of GAL responsible for binding and activation of GAL receptors in rat gastric smooth muscle cells. The data acquired in the course of our structure-activity relationship studies suggest that both N- and C-terminal fragment of GAL molecule contribute towards the affinity and activity of GAL gastric smooth muscle cell receptors. Moreover, we concluded that positions 2, 3, 4, 6, 8 and 14 in the amino acid sequence of GAL may play important roles in binding and activation of GAL receptors in rat gastric smooth muscle cells. 相似文献
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R P Korolkiewicz Z Konstański P Rekowski J Ruczyński A Szyk M Grzybowska K Z Korolkiewicz J Petrusewicz 《Journal of physiology and pharmacology》2001,52(1):127-136
The activity of porcine galanin (Gal) fragments and analogues were tested in vitro using rat gastric fundus strips. The peptides contracted longitudinal smooth muscle in a concentration-dependent manner with the following order of potency: [Nle4]Gal(1-15), Gal(-15), [Cle4]Gal(1-15), [Hse6]Gal(1-15), [Va14]Gal(1-15), [Ile4]Gal(1-15), [endoTrip2a, Cle4]Gal(1-15), [desThr3, Cle4]Gal(1-15), [D-Leu4] Gal(1-15), [desLeu4]Gal(1-15). On the contrary [desTrp2, Val4]Gal (1-15) remained inactive up to 10 microM. The values of Hill's coefficients estimated from the appropriate concentration-contraction curves for all analogues except for [Val4]Gal(1-15), [Hse6]Gal(1-15), [endoTrp2a,Cle4]Gal(1-15), [desLeu4]Gal(1-15) and [D-Leu4] Gal(1-15) did not significantly differ from unity. Our results indicate that the integrity of the first four N-terminal amino acids of Gal molecule is essential for the full excitatory myogenic action of the peptide in rat gastric fundus. Similarly, substitution, addition or deletion of amino acid residues in positions two, three, four and six can considerably influence the ability of Gal analogues to interact with Gal receptors. The data acquired in the course of our structure-activity study suggest that both N- and C-terminals of Gal molecule contribute towards the affinity and activity of Gal in rat gastric smooth muscle cell receptors. 相似文献
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