Leukotriene D4-induced hypotension is reversed by thyrotropin-releasing hormone.
Injection of leukotriene D4 (LTD4, 20 micrograms/kg, i.a.) to conscious spontaneous hypertensive (SHR) rats produces a short-lasting pressor and tachycardic response followed by prolonged hypotension and bradycardia. Plasma norepinephrine and epinephrine were elevated at the peak pressor/tachycardic phase as well as at the hypotensive phase. Injection of thyrotropin-releasing hormone (TRH, 2 or 5 mg/kg) at the peak of the LTD4-induced hypotension resulted in prompt reversal of the hypotension and bradycardia in a dose-related manner. Naloxone (5 mg/kg) had no effect on blood pressure and heart rate of LTD4-treated SHR rats. Pretreatment with TRH (5 mg/kg) did not prevent the depressor effect of LTD4, but attenuated the bradycardic effect of this leukotriene. In addition, TRH had no effect on LTD4-induced hypotension in the pithed SHR rat. These results suggest that TRH might exert beneficial effects in hypotensive states mediated by leukotrienes or other mediators of anaphylactic reactions.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004351:Drug Resistance; D004837:Epinephrine / Q000097:blood; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D013189:SRS-A / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013189:SRS-A; D009270:Naloxone; D013973:Thyrotropin-Releasing Hormone; D009638:Norepinephrine; D004837:Epinephrine