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In experiments on 23 dogs and 46 cats changes in hemodynamics were studied under conditions of experimental myocardial infarction. The finding was that there was a reduction in the minute and stroke cardiac volume, and an increase in the blood flow circulation general time. At the early periods of experimental myocardial infarction peripheral blood vessel resistance was increased.

1. After injection of acetylcholine directly into the region of the gigantocellular reticular nucleus of the brainstem marked changes are observed in the minute and systolic blood volumes, total peripheral resistance of the vessels and systemic arterial pressure. 2. Pressor neurons of the bulbar vasomotor center and also structures of the central nuclei of the vagus nerve system are evidently responsible for these changes. 3. The experimental results raise the question of a possible selective effect of acetylcholine on structures of the bulbar vasomotor center.