Medvedev O S, Val'dman A V, Titov M I
Biull Eksp Biol Med. 1981 May;91(5):574-6.
Intracisternal administration of leu- or met-enkephalins in a dose of 100 micrograms into unanesthetized cats evoked a short-lasting elevation of arterial pressure and tachycardia. After 1.5-2 minutes the blood pressure returned to normal and bradycardia developed (heart rate = 86 +/- 3.4% of initial). Alterations in the arterial pressure and heart rate were prevented by naloxon in a dose of 50-100 micrograms administered into the 4th ventricle. Leu-enkephalin inhibited the sensitivity of the baroreceptor reflex and increased by 69% the pressor reactions evoked by hypothalamus stimulation. Met-enkephalin was half as potent with respect to the baroreceptor reflex and exerted no effect on the hemodynamic reactions evoked by hypothalamus stimulation.
