Vascular beta-adrenoceptor blocking activity of endotoxin and pertussis toxin from Bordetella pertussis in rats.
Isolated and purified leucocytosis promoting factor (LPF), alternatively described as pertussis toxin, reduced the hypotension after beta 2-adrenoceptor stimulation with salbutamol as well as the negative chronotropic activity induced by the muscarinic receptor stimulant arecoline 4 days after its injection into rats. These inhibitory effects of LPF were accompanied by a reduction in basal blood pressure. No effect on autonomic responsiveness or blood pressure was observed 5 h after injection of LPF. Sublethal doses of purified B. pertussis endotoxin (LPS) elicited neither vascular beta 2-adrenergic nor cardiac cholinergic blockade 4 days following injection. Only a distinct vascular beta 2-adrenolytic effect was measured 5 h after pretreatment with the same doses of LPS. This beta 2-adrenoceptor hyporesponsiveness was accompanied by neither an anticholinergic nor a hypotensive effect, but rather by a slight but significant elevation of the blood pressure. In conclusion, both components of B. pertussis (LPS and LPF) give rise to vascular beta 2-adrenergic hyporesponsiveness irrespective of blood pressure effects. There is an important difference between both components with respect to their various kinetic profiles for this phenomenon: an early occurring and short-lasting beta 2-adrenergic blockade for LPS and a late occurring LPF-mediated beta 2-adrenergic blockade.
D000319:Adrenergic beta-Antagonists; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D003971:Diastole; D004731:Endotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D006339:Heart Rate / Q000187:drug effects; D007700:Kinetics; D008297:Male; D037342:Pertussis Toxin; D051381:Rats; D011919:Rats, Inbred Strains; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D000319:Adrenergic beta-Antagonists; D004731:Endotoxins; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin