Pulmonary vascular responses to ma huang extract.
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.
Fields
Aaron M
AM
Department of Anesthesiology, Texas Tech University School of Medicine, Health Sciences Center, Lubbock, TX 79430, USA.
Kaye
Alan D
AD
Richards
Todd A
TA
Ibrahim
Ikhlass N
IN
Heavner
James E
JE
Dewitt
Bracken J
BJ
Bayer
Erin Z
EZ
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*
D000317:Adrenergic alpha-Antagonists; D010936:Plant Extracts; D018340:Receptors, Adrenergic, alpha-1; D014662:Vasoconstrictor Agents; D011224:Prazosin; D010646:Phentolamine