The general anesthetic propofol (PRO) decreases arterial blood pressure and slows heart rate. To investigate the effects of PRO on the baroreflex, synaptic potentials evoked by solitary tract (ST) stimulation were recorded in mNTS where baroreceptor afferent fibers are known to terminate. In a quasi-horizontal brain slice preparation, ST stimulation >1.5mm from the recording electrode evoked a short latency EPSP, a long latency IPSP, or a combination EPSP/IPSP where the EPSP always preceded the IPSP. EPSPs were blocked with the AMPA Glu antagonist NBQX. IPSPs were blocked with the GABAA antagonist biccuculine or by NBQX. This is consistent with previous studies which suggest that ST evoked EPSPs are monosynaptic and ST evoked IPSPs are polysynaptic possibly via mNTS interneurons. Bath applied PRO increased the IPSP amplitude and decreased the EPSP amplitude in a dose dependent manner. 10μM, 50μM and 100μM PRO facilitated the IPSP to 200%, 170% and 150% control respectively revealing a biphasic dose response curve. 50μM and 100μM PRO attenuated the EPSPs by 76%, and 61% respectively. Note that the PRO facilitation of the IPSP was greatest at the lowest concentration tested Our results suggest that PRO may attenuate baroreflex function by actions in mNTS to increase inhibitory and decrease excitatory synaptic transmission.
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology