ISSN:
1432-1912
Keywords:
Histamine
;
Guinea-pig atria
;
Uptake and metabolism
;
Inotropic responses
;
Chronotropic responses
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. The uptake of radiolabelled 14C-histamine into guinea-pig isolated left atria was determined. 2. Mepyramine up to 10−7 M had no significant effect upon the uptake of total radioactivity. Metiamide (10−4 M) produced a small but not significant inhibition of uptake. SK & F 91581 (10−4 M) and amodiaquine (10−4 M) both significantly inhibited uptake by 48.2±4.2 and 56.7±1.2% respectively. 3. The metabolism profiles of radiolabelled histamine after 5 and 30 min incubation were examined by thin-layer chromatography. 4. SK & F 91581 (10−4 M) and amodiaquine (10−4 M) reduced the proportion of Nτ-methyl-histamine and acid metabolites after a 30 min incubation. The levels of unmetabolized histamine were elevated. This may explain their inhibitory action upon histamine uptake. 5. The effects of mepyramine, metiamide, SK & F 91581 and amodiaquine were then examined upon the positive inotropic and chronotropic responses of isolated left and right atria to histamine. 6. Mepyramine (10−7 M) inhibited the positive inotropic responses only (H1), whereas metiamide (10−4 M) inhibited the positive chronotropic responses only (H2). SK & F 91581 (10−4 M) had no effect upon these responses and amodiaquine (10−5 M) depressed the maxima of the rate response dose-response curves. 7. The relationship between uptake and metabolism of histamine and its pharmacological response is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00499258
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