ALPHA-ADRENERGICALLY AND BETA-ADRENERGICALLY MEDIATED RESPONSES IN ISOLATED LUNG STRIPS OF GUINEA-PIGS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 32  (3) , 459-472
Abstract
Thin strips of lung parenchyma from guinea pigs were mounted in an isolated tissue bath and placed under an initial tension of 1.2 gm. Drug-induced changes in resting tension were recorded isometrically on the addition of representative .alpha.- and .beta.-adrenergic agonists. Lung strips relaxed after challenge with isoproterenol, 10-9-10-6M (.beta.-adrenergic agonist), and contracted following challenge with phenylephrine, 10-6-10-4M (.alpha.-adrenergic agonist). The responses of lung strips to norepinephrine [NE], 10-8-10-4 M (mixed .alpha.- or .beta.-agonist) were influenced by the presence of an .alpha.- or .beta.-adrenergic antagonist: pretreatment with phentolamine, 10-5 M (.alpha.-antagonist) caused relaxant responses to NE; pretreatment with propranolol, 10-5 M (.beta.-antagonist) caused contractile responses. Cocaine, an uptake-1 inhibitor, potentiated the contractile effect of NE but not the relaxant effect of isoproterenol or NE. .alpha. And .beta.-adrenergic receptors mediating contraction and relaxation, respectively, exist in guinea pig lungs.