Three Distinct Vasomotor Mechanisms Activated by Dmpp.

佐久間 昭 * Present Address : Department of Pharmacology , Institute for Cardiovascular Diseases, Tokyo Medi cal & Dental University, Bunkyu-ku, Tokyo. Ftc. 1. In autoperfusion of dog hindquarters, distal electro stimulation (E) of the divided lumbar sympathetic chains and i.a. DMPP (D) are serially challenged by fl-TM 10, tripelennamine (PBZ) and atropine (Atr). Intraarterial injection of 20 to 100 ag of dimethylphenylpiperazinium (DMPP) into the perfused hindquarters produced vascular response in the perfused area in autocirculation preparation of the dog. In 2 cases a small rise followed by a fall, and in 6 a moderate rise followed by a slight fall were observed, the hypotensive component tending to be less prominent after transection of the sympathetic chains at L5-L6. i) Treatment of the animal with p,-TM 10, guanethidine or bretylium in 5 to 10 mg/kg, i.v., reversed the pressor effect of i .a. DMPP. ii) Treatment with antimuscarinic doses of atropine or scopolamine strikingly enhanced the pressor effect or reduced the depressor component of DMPP