[The effects of a cardioactive hypothalamic neurohormone on the isolated rat heart]

On the isolated perfused by Langendorf at heart the cardioactive hypothalamic neurohormone NG3a (2 x 10(-5) g/ml) significantly decreased the coronary flow rate; the effect persisted during 5-10 min, after that the second phase appeared which was expressed by the increase of coronary flow rate. The maximum effect was 122% compared with control. The second phase appeared in 30-45 min after infusion of NG3a. NG3a did not influence the heart rate, but sometimes (7.3% cases) during the maximum increase of coronary flow the bradyarrhythmia was registered. It has been concluded that NG3a influences directly the coronary vessels.