Effect of intravenous epinephrine on uterine artery blood flow velocity in the pregnant guinea pig.

The purpose of the present study was to determine the effect of intravenously administered epinephrine on the maternal cardiovascular response and uterine artery blood flow velocity (UBFV) in the pregnant guinea pig. Epinephrine (0.2, 0.5, and 1.0 micrograms/kg) and lidocaine (0.4 mg/kg, with and without 0.2 micrograms/kg of epinephrine) were administered intravenously to seven chronically instrumented pregnant guinea pigs near term. Lidocaine without epinephrine did not significantly alter maternal heart rate (MHR), maternal mean arterial pressure (MMAP), or UBFV. Epinephrine, with and without lidocaine, resulted in a transient decrease in MHR. Further, epinephrine, with and without lidocaine, resulted in significant elevations in MMAP and significant, dose-related reductions in UBFV. Mean (+/- SEM) UBFV was 72 +/- 4%, 56 +/- 4%, and 40 +/- 5% of baseline at 30 s after administration of epinephrine, 0.2, 0.5, and 1.0 micrograms/kg, respectively. It is concluded that these small intravenous boluses of epinephrine result in significant, although transient, reductions in UBFV in the pregnant guinea pig.