alpha-Fluoromethylhistidine decreases the histamine content of the rat right atrium under the influence of sympathetic activity.
alpha-Fluoromethylhistidine (alpha-FMH; 65 mg/kg, i.p.), a specific inhibitor of histidine decarboxylase, significantly decreased the histamine content of the rat right atrium in a time-dependent manner; the maximal decrease of 22.2% was observed 4 h after injection. However, alpha-FMH had no significant effect on the histamine content of the left atrium or the ventricles. The alpha-FMH-induced decrease in the right atrial histamine content was not observed in rats pretreated with 6-hydroxydopamine (25 mg/kg, i.p.). Two i.p. injections of 10 and 5 mg/kg of propranolol and the cardioselective beta 1-adrenoceptor antagonist metoprolol almost completely inhibited the alpha-FMH-induced histamine decrease. On the other hand, phentolamine (10 mg/kg, i.p.) had no influence on the histamine-decreasing action of alpha-FMH. These results suggest that in the rat right atrium there is a histamine pool where a rapid turnover of histamine is maintained by normal sympathetic activity.
Yoshitomi
I
I
Department of Pharmacology, Okayama University Medical School, Japan.
Oishi
R
R
Itoh
Y
Y
Saeki
K
K
Senoo
Y
Y
Teramoto
S
S
D000818:Animals; D006321:Heart / Q000187:drug effects; D006632:Histamine / Q000378:metabolism*; D006639:Histidine / Q000031:analogs & derivatives*; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology*; D008790:Metoprolol / Q000494:pharmacology; D009206:Myocardium / Q000378:metabolism*; D016627:Oxidopamine; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors
D006892:Hydroxydopamines; D008762:Methylhistidines; D006639:Histidine; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D016627:Oxidopamine; D011433:Propranolol; D008790:Metoprolol