1,721,004 research outputs found
Relaxant effect of the H2-receptor antagonist oxmetidine on guinea-pig and human airways.
No full textThe effects of three different H2-receptor antagonists (cimetidine, ranitidine and oxmetidine) were tested on isolated preparations of guinea-pig trachea and human bronchus against contractions induced by acetylcholine, histamine and potassium chloride (KCl). In addition, their influence on calcium concentration-response curves in guinea-pig tracheal spirals was examined in a potassium-rich solution (30 mM). Finally, their effects were studied in vivo against acetylcholine and histamine-induced bronchoconstriction in anaesthetized guinea-pigs. In guinea-pig isolated trachea, oxmetidine--in contrast to cimetidine and ranitidine, which were completely inactive--induced a concentration-dependent relaxation regardless of the excitatory stimulus: its--log EC50 values (i.e. the negative log concentration that caused a 50% relaxation) were 3.46 +/- 0.11, 4.61 +/- 0.09 and 4.20 +/- 0.12 against acetylcholine, histamine and KCl, respectively. In Ca2+-free, K+-enriched solution, the compound was able to inhibit Ca2+-induced contractions at concentrations close to those needed to counteract the spasmogenic effect of histamine in normal Krebs solution. Results obtained in the human bronchus preparation were similar to those observed in guinea-pig tracheal spirals. When tested against acetylcholine or histamine-induced bronchoconstriction in vivo, oxmetidine (10 and 30 mg Kg-1 intravenously) significantly reduced the increase in pulmonary airway resistance (Raw) induced by both agents. Once again, cimetidine and ranitidine were completely ineffective. In summary, oxmetidine displayed non-specific antispasmogenic activity on guinea-pig and human airways. This effect, which is independent of H2-receptor blockade, represents a side-effect of the drug which may be connected to its interference with Ca2+ influx and the action or release of intracellular Ca2+
Nociceptin/orphanin FQ inhibits electrically induced contractions of the human bronchus via NOP receptor activation
No full textNociceptin/orphanin FQ (N/OFQ) has been reported to inhibit neurogenic contractions in various tissues, including guinea pig airways.
In the present study, we investigated the ability of N/OFQ to affect cholinergic contractions of human bronchi elicited by electrical field
stimulation (EFS). Tissues were obtained from 23 patients undergoing surgery for lung cancer. EFS (20 Hz, 320 mA, 1.5 ms, 10 s) was applied
five times every 20 min. Contractions induced by EFS were abolished by either TTX (1 M) or atropine (1 M) and concentration-dependently
(10 nM-1 M) inhibited by N/OFQ (Emax, 11.5±1.8% inhibition). The inhibitory effects of N/OFQ were mimicked by the N/OFQ receptor
(NOP) ligand [Arg14, Lys15]N/OFQ which displayed however, higher significant maximal effects (17.7±2.9% inhibition, P < 0.05). The
actions of N/OFQ and [Arg14, Lys15]N/OFQ were not affected by naloxone (1 M) while prevented by the selective NOP receptor antagonist
UFP-101 (10 M). Moreover, the inhibitory effects of NOP agonists were no longer evident in tissues treated with tertiapin (10 M), an
inhibitor of inward-rectifier potassium channels. In conclusion, the present data demonstrate that N/OFQ inhibited acetylcholine (ACh)
release in the human bronchi via NOP receptor activation. This effect may involve stimulation of potassium currents
The involvement of sensory neuropeptides in airway hyper-responsiveness in rabbits sensitized and challenged to Parietaria judaica
No full textRole of tachykinins in the bronchoconstriction induced by HCl intraesophageal instillation in the rabbit
No full text
Nociceptin inhibits airway microvascular leakage induced by HCl intra-oesophageal instillation
No full textTachykinins and airway microvascular leakage induced by HCl intra-oesophageal instillation
No full textThe involvement of sensory neuropeptides in airway hyper-responsiveness in rabbits sensitized and challenged to Parietaria judaica
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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