Histamine and Nt-methylhistamine in the circulation during intravenous infusion of histamine in normal volunteers.
Plasma levels of histamine and Nt-methylhistamine were measured simultaneously by high performance liquid chromatography during the intravenous infusion of histamine acid phosphate in six normal volunteers. Progressive, dose-related increases in plasma histamine were noted, reaching a maximum value of 3.1 +/- 0.14 ng ml-1 corresponding to a maximum infusion rate of 180 ng kg-1 min-1 (means +/- SEM). Increases in plasma histamine were accompanied by a significant dose-related fall in mean diastolic blood pressure (baseline 74.0 +/- 4.4 mm Hg falling to 60.0 +/- 3.3 mm Hg at maximum infusion rate, p less than 0.001) and an increase in pulse rate (baseline 76.3 +/- 2.8 beats min-1 rising to 89.24 beats min-1 at maximum infusion rate, p less than 0.05). All subjects exhibited facial flushing, the threshold plasma histamine level for this effect being 1.3 +/- 0.15 ng ml-1 corresponding to an infusion rate of 60 ng kg-1 min-1. Elevation of plasma Nt-methylhistamine was seen in only one subject, who exhibited a level of 0.5 ng ml-1 at the highest infusion rate. These results suggest that measurements of plasma Nt-methylhistamine are unlikely to provide a useful index of histamine release into the circulation.
Sheinman
B D
BD
Academic Department of Respiratory Medicine, St Bartholomew's Hospital, London, UK.
Devalia
J L
JL
Wylie
G
G
Davies
R J
RJ
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006632:Histamine / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008761:Methylhistamines / Q000097:blood*; D008875:Middle Aged; D011674:Pulse / Q000187:drug effects
D008761:Methylhistamines; D006632:Histamine; C048140:N-methylhistamine