Effect of heparin sodium and enoxaparin on spasmogen-induced contraction of isolated sensitized guinea pig tracheal strips and on sensitized rat peritoneal mast cells

ABSTRACT

Atopic asthma is a chronic inflammatory disorder of the airways associated with hyperresponsiveness to various bronchoconstrictor stimuli. Prompt search effort to identify alternate therapy that are effective in poorly controlled asthma while receiving standard therapy. Heparin possesses multiple non-anticoagulant properties, including anti-allergic and anti-inflammatory actions. The present study was directed to investigate the effects of unfractionated heparin [UF-heparin, heparin sodium] and low molecular weight heparin [LMWheparin, enoxaparin] on spasmogen, [histamine, acetyl choline [Ach], serotonin and potassium chloride [KCII] - induced contraction of isolated tracheal smooth muscles [TSM], and on antigen-induced histamine release from sensitized mast cells. Tracheal smooth muscle obtained from guinea pig sensitized with ovalbumin and was suspended in an organ bath containing oxygenated [95% 02, 5%C 02] Krebs-Henseleit buffer at 37°C. The influence of drugs on the in vitro reactivity of tracheal smooth muscle was evaluated. After an equilibration period, the tissues were treated with heparin sodium or enoxaparin dissolved in phosphate-buffered saline [PBS], at concentrations of 0.1, 1, or 10 U/ml. After 15 minutes incubation with either drugs, the response of the preparation to submaximal concentrations of histamine, ACh, serotonin and KC1 was tested. The percentage of change of height of contraction induced by each concentration of the tested drugs was measured against the height of contraction induced by submaximal dose of spasmogens on the same tracheal spiral strip. Also, the actively sensitized peritoneal mast cells of rats were pre-incubated with heparin sodium or enoxaparin in the same above concentrations prior to antigen challenge. UF-heparin caused a dose-dependent inhibition of histamine -induced contraction of [TSM] by 8 +/- 1.3% [0.lU/ml], 20 +/- 3.2% [lU/mi] and 44 +/- 6.0% [1OU/ml] [F=126, P<0.05]. The histamine-induced [TSM] contractions were inhibited by 30.7 +/- 5.0%, 46.1 +/- 7.8% and 61.5 +/- 6.5% with enoxaparin at doses of [0.1, 1 and 10 U/ml] respectively [F33.3, p<0.05]. UF-heparin attenuated KC1 -induced contraction of [TSM] in dose-dependent fashion. A dose of 0.1U/ml caused 14.2 +/- 3.3% inhibition, a dose of lU/ml caused 28.5 +/- 4.9% inhibition, whereas a dose of 10 U/ml caused 40 +/- 3.4% inhibition [F=64.7, p<0.05]. Pretreatment with enoxaparin attenuated KC1-induced contraction in dose-dependent fashion. Contraction was inhibited by 30 +/- 3.7% [0.1 U/ml], 45.4 +/- 5.9% [IU/ml] and 54.5 +/- 6.6% [10 U/ml] [F=29.9, p<0.05]. In vitro, preincubation with either heparin sodium or enoxaparin [0.1, 1 and 10 U/ml] inhibited the release of histamine from rat peritoneal mast cells in a dose dependent fashion [8.3 +/- 1.7%, 16.6 +/- 2.6% and 31.2 +/- 3.7 [F= 103.66, peO.O5] respectively for heparin sodium and 18.1 +/- 1.7%, 25 +/- 3.4% and 50 +/- 5.6% [F=l 10.6, p<0.05] respectively for enoxaparin. It is concluded that UF-heparin and LMW heparin reduced histamine and KCL- induced TSM contraction, but failed to inhibit ACh and serotonin-induced contraction. The bronchodilator effect of heparin is molecular-weight dependent. UF-heparin and LMW-heparin inhibited the release of histamine from sensitized rat peritoneal mast cells in a dose dependent fashion