Metabolism and Effects of Vasoactive Substances in the Lung
8) Effect of glucocorticoid on the contraction and relaxation of guinea-pig trachea with various drugs
1976 Volume 14 Issue 7 Pages 379-383
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1976 Volume 14 Issue 7 Pages 379-383
Asthma is a clinical syndrome manifested by reversible and intermittent obstruction of the bronchi. Over the past several years numerous in vivo studies have indicated that asthmatic individuals are deficient in their response to β-adrenergic agents, compounds that are known to raise cyclic AMP levels in many tissues. In such a case steroid therapy provides the marked relief, but the mechanism of this steroid therapy is still unknown.
Present investigation was done in an effort to clarify the mechanism of steroid therapy in an asthmatic patient. Male guinea-pigs, weighing 250-300g, were killed. Guinea-pig trachea (GPT) was removed and suspended in a glass chamber and superfused with Krebs-Hensleit solution at 37°C saturated with oxygen and carbon dioxide (95: 5, v/v). Contraction and relaxation of GPT were detected by an isotonic transducer and displayed on a polyrecorder.
1) GPT showed contractions with acetylcholine, histamine, serotonin, prostaglandin F2α and bradykinin. And these contractions became smaller with continuous infusion of prednisolon (5μg/ml).
2) GPT showed relaxations with isoproterenol, neophyllin and prostaglandin E2. And these relaxations with isoproterenol and neophyllin became bigger with continuous infusion of prednisolon (5μg/ml), but prostaglandin E2 showed no increase of relaxation.
3) These results suggest that prednisolon increases the effect of pronchodilator and decreases the effect of bronchoconstrictors.
