title: Pulmonary vascular responses to ma huang extract.
abstract: OBJECTIVE
  To test the hypothesis that ma huang induces a pressor response in the pulmonary vascular bed of the cat by activating alpha(1)-adrenergic receptors
  
  
  METHODS
  Prospective vehicle-controlled study.
  
  
  METHODS
  Research laboratory at Texas Tech University School of Medicine, Lubbock, TX.
  
  
  METHODS
  Intact chest preparation; adult mongrel cats.
  
  
  METHODS
  The effects of phentolamine, a nonselective alpha receptor blocker, and prazosin, an alpha(1) selective antagonist, were investigated on pulmonary arterial responses to ma huang, phenylepherine, norepinephrine, and U-46619, a thromboxane A(2) mimic.
  
  
  RESULTS
  Lobar arterial perfusion pressure was continuously monitored, electronically averaged, and recorded with constant flow in the isolated left lower lobe vascular bed of the cat. Phentolamine and prazosin significantly reduced vasoconstrictor pulmonary perfusion pressure increases induced by ma huang.
  
  
  CONCLUSIONS
  Ma huang has significant vasopressor activity in the pulmonary vascular bed of the cat mediated predominantly by alpha(1)-adrenergic receptor activation.
authors: Department of Anesthesiology, Texas Tech University School of Medicine, Health Sciences Center, Lubbock, TX 79430, USA.
authors: Aaron M
authors: AM
authors: Fields
authors: Alan D
authors: AD
authors: Kaye
authors: Todd A
authors: TA
authors: Richards
authors: Ikhlass N
authors: IN
authors: Ibrahim
authors: James E
authors: JE
authors: Heavner
authors: Bracken J
authors: BJ
authors: Dewitt
authors: Erin Z
authors: EZ
authors: Bayer
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D029790:Ephedra sinica; D005260:Female; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D011446:Prospective Studies; D011652:Pulmonary Circulation / Q000187:drug effects*; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D010936:Plant Extracts; D018340:Receptors, Adrenergic, alpha-1; D014662:Vasoconstrictor Agents; D011224:Prazosin; D010646:Phentolamine