Drugs online research references
J Pharmacol Exp Ther. 1997 Dec;283(3):1102-9.
Absence of tachykinin involvement in leukotriene D4 and antigen-induced contraction of guinea pig isolated bronchus.
Cibulsky SM, Thompson DC.
Department of Pharmaceutical Sciences, University of Colorado School of Pharmacy, Denver, Colorado 80262-0238, USA.
In guinea pig airways, contractions induced by leukotriene D4 or antigen are thought to be mediated primarily by an action of the agonist or of released mast cell-derived mediators directly on the airway smooth muscle cell. An indirect contractile action mediated by endogenous tachykinins also has been described for both of these stimuli. The present study evaluated the contribution of endogenous tachykinins to ovalbumin- and leukotriene D4-induced contractions in the guinea pig bronchus by modulating the concentrations of tachykinins within the tissues and by using neurokinin receptor antagonists. Acute depletion of tachykinins with capsaicin had no effect on responses elicited by either stimulus. Similarly, tetrodotoxin treatment failed to influence leukotriene D4-induced contractions. Inhibitors of neutral endopeptidase (thiorphan) and angiotensin-converting enzyme (lisinopril) enhanced neurally mediated tachykininergic responses and potentiated leukotriene D4. The latter effect persisted in the presence of tetrodotoxin or the neurokinin antagonists CP99994 and SR48968 and in tissues treated acutely with capsaicin. The potentiation was absent, however, from bronchi incubated with L-cysteine. Ovalbumin-induced contractions were unaltered by inhibition of neutral endopeptidase and angiotensin-converting enzyme. These observations suggest that tachykinins are not involved in mediation of leukotriene D4- or antigen-induced contractions of the guinea pig bronchus. The ability of protease inhibitors to potentiate leukotriene D4 but not antigen-induced responses is therefore ascribed to inhibition of bioinactivation of leukotriene D4 to leukotriene E4.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9399982&dopt=Abstract
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Stem Cells. 1997;15(6):455-60.
Inhibitory action of the peptide AcSDKP on the proliferative state of hematopoietic stem cells in the presence of captopril but not lisinopril.
Chisi JE, Wdzieczak-Bakala J, Riches AC.
School of Biological and Medical Sciences, University of St. Andrews, Fife, Scotland.
The effect of Angiotensin I-converting enzyme (ACE) inhibitors on their own and in combination with the peptide AcSDKP on the proliferation of hematopoietic stem cells has been investigated. Hematopoietic stem cells from murine bone marrow induced into cell cycle following exposure to 2 Gy gamma-irradiation were incubated in vitro for up to 24 h in the presence of medium, captopril/lisinopril, AcSDKP, and AcSDKP with either ACE inhibitor. Hematopoietic stem cells were monitored using the high proliferative potential-colony forming cell-1 (HPP-CFC-1) population cloned in the presence of human IL-1 beta, murine IL-3, and murine M-CSF. No significant inhibitory effect was observed in the presence of AcSDKP on its own and AcSDKP in combination with lisinopril. However, there was a significant inhibition of stem cell cycling when AcSDKP and captopril were combined. This suggests that captopril inhibits AcSDKP breakdown better than lisinopril. The combination of AcSDKP and captopril also had an inhibitory effect on cell recruitment into S phase. The fact that a combination of AcSDKP and captopril switches cycling hematopoietic stem cells out of cycle indicates the importance of the N-active catalytic site of ACE in AcSDKP hydrolysis in vitro. Thus, AcSDKP in combination with appropriate ACE inhibitors may be of use in regulating the proliferation of hematopoietic stem cells in vitro.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9402658&dopt=Abstract
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Arch Mal Coeur Vaiss. 1997 Aug;90(8):1131-4.
[Renal vascular responses of bradykinin in the isolated rat kidney]
[Article in French]
Bagate K, Develioglu L, Michel B, Grima M, Imbs JL, Barthelmebs M.
Institut de pharmacologie, faculte de medecine, universite Louis-Pasteur, Strasbourg.
Kinins, by an autocrine or paracrine hormonal action, are potent modulators of regional vasomotricity. Their effects on the renal circulation are not well defined. The aim of this study was to analyse the renal vascular response induced by bradykinin, to precise the type(s) of receptor involved and to evaluate the contribution of various peptidases in the local catabolism of the kinin. Experiments were performed on the isolated rat kidney, perfused in an open circuit, at a constant flow of 8 mL/min, with a Tyrode's solution. Vasodilator responses were evaluated after renal vascular tone had been restored by a continuous perfusion with prostaglandin F2 alpha. Infusion of bradykinin (0.1-30 nM) induced a concentration-dependent renal vasorelaxation. A maximal response of 39.5 +/- 2.8% (n = 32) reversion of the tone induced by prostaglandin F2 alpha (about 50% of the maximal response induced by acetylcholine on the same kidneys) was obtained at 30 nM. Bradykinin-induced vasodilatation was completely inhibited by HOE 140 (10 nM), a selective bradykinin B2 receptor antagonist. At a supramaximal concentration of 300 nM, bradykinin-induced vasorelaxation was modulated by a concomitant vasoconstriction. A concentration-dependent vasoconstriction was also obtained with desArg9 bradykinin (1-8 microM), a selective agonist of the bradykinin B1 receptor. The inhibition of neutral endopeptidase by phosphoramidon (10 microM) or the inhibition of carboxypeptidase M by MGTPA (10 microM) did not modify the bradykinin-induced renal vasorelaxation. On the other hand, the inhibition of angiotensin I converting enzyme by lisinopril (1 microM) potentiated by about 32% the vasorelaxant response induced by 30 nM bradykinin (52.3 +/- 11.8% relaxation, n = 5, p < 0.05). Present results demonstrate that 1) bradykinin primarily evokes B2 receptor-linked renal vasodilatation, 2) bradykinin B1 receptors appear also to be present on the rat renal vasculature and 3) angiotensin 1 converting enzyme contributes to the local vascular catabolism of the kinin.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9404422&dopt=Abstract
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