title: Pulmonary vasoconstrictive and bronchoconstrictive responses to anaphylaxis are weakened via β2-adrenoceptor activation by endogenous epinephrine in anesthetized rats.
abstract: BACKGROUND
  Patients treated with propranolol, a nonselective β-adrenoceptor antagonist, have increased incidence and severity of anaphylaxis. We determined whether β1- or β2-adrenoceptor antagonist modulated pulmonary vasoconstriction and bronchoconstriction in rat anaphylactic hypotension.
  
  
  METHODS
  Anesthetized ovalbumin-sensitized male Sprague-Dawley rats were randomly allocated to the following pretreatment groups (n = 7/group): (1) sensitized control (nonpretreatment), (2) propranolol, (3) the selective β2-adrenoceptor antagonist ICI 118,551, (4) the selective β1-adrenoceptor antagonist atenolol, and (5) adrenalectomy. Shock was induced by an intravenous injection of the antigen. Mean arterial pressure, pulmonary arterial pressure, left atrial pressure, central venous pressure, portal venous pressure, airway pressure, and aortic blood flow were continuously measured.
  
  
  RESULTS
  In either sensitized control or atenolol-pretreated rats, mean arterial pressure and aortic blood flow decreased substantially, whereas pulmonary arterial pressure and airway pressure did not increase soon after antigen injection. In contrast, in rats pretreated with either propranolol, ICI 118,551, or adrenalectomy, airway pressure significantly increased by 14 cm H2O, and pulmonary arterial pressure by 7.5 mmHg after antigen injection. At 2.5 min after antigen injection, the plasma concentration of epinephrine increased 14-fold in the sensitized rats except for the adrenalectomy group. Portal venous pressure after antigen injection increased by 16 mmHg similarly in all sensitized rats. All of the sensitized control group and two of the atenolol group were alive for 60 min after antigen injection, whereas all rats of the propranolol, ICI 118,551, and adrenalectomy groups died within 50 min after antigen injection.
  
  
  CONCLUSIONS
  The pulmonary vasoconstrictive and bronchoconstrictive responses to systemic anaphylaxis were weakened via β2-adrenoceptor activation by epinephrine endogenously released from the adrenal gland in the anesthetized Sprague-Dawley rats.
authors.affiliation: Department of Physiology II, Kanazawa Medical University, Uchinada, Japan.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Toshishige
authors.initials: T
authors.lastname: Shibamoto
authors.forename: Yuhichi
authors.initials: Y
authors.lastname: Kuda
authors.forename: Chieko
authors.initials: C
authors.lastname: Ohmukai
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kurata
mesh_terms: D000315:Adrenalectomy; D058671:Adrenergic beta-1 Receptor Antagonists / Q000494:pharmacology; D058672:Adrenergic beta-2 Receptor Antagonists / Q000494:pharmacology; D000707:Anaphylaxis / Q000503:physiopathology*; D000758:Anesthesia; D000818:Animals; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology*; D002395:Catecholamines / Q000097:blood; D002496:Central Venous Pressure / Q000187:drug effects / Q000502:physiology; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D004837:Epinephrine / Q000494:pharmacology / Q000502:physiology*; D006321:Heart / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D010047:Ovalbumin / Q000276:immunology; D011169:Portal Vein / Q000502:physiology; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018343:Receptors, Adrenergic, beta-2 / Q000187:drug effects / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D058672:Adrenergic beta-2 Receptor Antagonists; D002395:Catecholamines; D018343:Receptors, Adrenergic, beta-2; D010047:Ovalbumin; D004837:Epinephrine