CARDIOVASCULAR-RESPONSES TO MICROINJECTION OF TRANS-(+ -)-ACPD INTO THE NTS WERE SIMILAR IN CONSCIOUS AND CHLORALOSE-ANESTHETIZED RATS/

The changes in mean arterial pressure (MAP) and heart rate (HR) in res ponse to the activation of metabotropic receptors in the nucleus tract us solitarii (NTS) with trans-(+/-)-1-amino-1,3-cyclopentanedicarboxyl ic acid (trans-(+/-)-ACPD) were evaluated in conscious and anesthetize d Wistar, male rats weighing 240-260 g (N = 8). The responses obtained with trans-(+/-)-ACPD were compared with the responses to L-glutamate (1 nmo1/100 nl), since in a previous study we showed that anesthesia converted a presser response to L-glutamate microinjected into the NTS of conscious rats to a depressor response in the same rats under uret hane or chloralose anesthesia. Microinjection of 3 doses of trans-(+/- )-ACPD(100, 500 and 1000 pmol/100 nl) produced a dose-dependent fall i n MAP (range, -20 to -50 mmHg) and HR (range, -30 to -170 bpm) under b oth conscious and chloralose anesthesia conditions. These data indicat e that; the cardiovascular responses to the activation of metabotropic receptors by trans-(+/-)-ACPD are not affected by chloralose anesthes ia while the cardiovascular responses to the activation of excitatory amino acid (EAA) receptors by L-glutamate are significantly altered.