HISTAMINE AGGRAVATED LEVOTHYROXINE-INDUCED CARDIOMYOPATHY IN GUINEA-PIGS

AIM: To study effects of histamine on cardiomyopathy. METHODS: Cardiom yopathy model was developed in guinea pig by ip levothyroxine 0.5 mg . kg(-1). d(-1) for 10 d. Langendroff's hearts were perfused. ECG and c ontractile force were recorded. Histamine (5 mu g) was given by intraa ortic injection. Histamine content of coronary venous effluent was det ermined fluorometrically. RESULTS: Attack of histamine on cardiomyopat hy was severer than that in normal hearts. Tachycardia was more promin ent; atrioventricular conduction block occurred earlier; decrease in c oronary flow was more marked. Uptakes of histamine were 37% in the mod el and 19% in the normal hearts (P < 0.01). CONCLUSION: Histamine aggr avated levothyroxine-cardiomyopathy.