Vascular anti-permeability effects of beta-receptor agonists and theophylline in the lung.
In conscious guinea-pigs the effect of theophylline, terbutaline and isoprenaline on histamine-induced increase in lung weight was examined. Animals exposed to a saline aerosol had a lung weight to body weight ratio of about 0.8%. Exposure to a histamine aerosol raised this value to about 1.1 (P less than 0.001). Theophylline 55 mg/kg and 110 mg/kg was given orally, terbutaline 0.1 mg/kg and isoprenaline 0.01 mg/kg and 0.03 mg/kg subcutaneously before exposure to histamine. The three drugs prevented the lung weight effect produced by histamine aerosol (P less than 0.01, P less than 0.001, P less than 0.001, P less than 0.1, P less than 0.001 respectively). Changes in lung blood content did not contribute to the weight-reducing effects. The potency ratio found between terbutaline and isoprenaline suggests that beta-2-receptors might be involved in the anti-permeability effect. Propranolol-treated animals did not survive in the histamine-aerosol unless they received theophylline; neither bronchodilator nor antipermeability effects of theophylline were antagonized by propranolol. It is concluded that in guinea-pigs theophylline and beta-agonists, in bronchodilating doses have the additional effect of preventing permeability oedema in the lung.
D000284:Administration, Oral; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D007279:Injections, Subcutaneous; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology*; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D008297:Male; D009929:Organ Size; D013726:Terbutaline / Q000008:administration & dosage / Q000494:pharmacology*; D013806:Theophylline / Q000008:administration & dosage / Q000494:pharmacology*
D006632:Histamine; D013806:Theophylline; D007545:Isoproterenol; D013726:Terbutaline