Increased myometrial blood flow evoked by substance P.

Substance P (SP), a vasoactive neuropeptide, has recently been demonstrated in the female genital tract. In the present paper we have investigated the relationship between substance P (0, 0.065, 6.5, 650 pmol X min-1 X kg-1) administered by close intraarterial infusions, and myometrial blood flow (MBF). The MBF was measured by the 133Xe washout technique in ten non-pregnant, estrogen pretreated, female rabbits anaesthetized with sodium pentobarbitone. SP increased MBF in a dose-dependent fashion. This effect was not influenced by cholinergic, adrenergic or enkephalinergic blocking agents, indicating a direct effect of substance P on vascular smooth muscle. Substance P may therefore play a physiological role in the local nervous control of myometrial blood flow.