1: Brain Res. 1999 Apr 10;824(2):147-52. 

Role of carbon monoxide in L-glutamate-induced cardiovascular responses in
nucleus tractus solitarius of conscious rats.

Silva CC, Almeida VA, Haibara AS, Johnson RA, Colombari E.

Department of Physiology, Universidade Federal de Sao Paulo, Escola Paulista de
Medicina, Rua Botucatu 862, Sao Paulo, SP 04023-060, Brazil.

Heme oxygenase degrades heme to form carbon monoxide. It has been reported that
heme oxygenase-derived carbon monoxide may interact with L-glutamate (L-Glu)
receptors in the nucleus tractus solitarius (NTS). Integrative studies suggest
that heme oxygenase inhibitors raise blood pressure, in part, by inhibiting
carbon monoxide formation in the NTS. The currents studies were designed to
determine if heme oxygenase inhibitors affect the cardiovascular actions of
L-Glu in the NTS. Accordingly, MAP and HR responses to unilateral
microinjections of L-Glu (5 nmol/100 nl) into the NTS were measured before and
after ipsilateral microinjections of zinc deuteroporphyrin 2,4-bis glycol
(ZnDPBG, 4.5 nmol/100 nl) or chromium mesoporphyrin (CrMP, 1.5 nmol/100 nl) in
awake rats chronically instrumented with NTS guide cannulaes and arterial
catheters. With respect to non-treatment (+36+/-5 mmHg, -107 bpm, n=10), ZnDPBG
pre-treatment attenuated the pressor and bradycardic responses to L-Glu (+7+/-3
mmHg, -10+/-6 bpm, P<0.05). CrMP similarly attenuated cardiovascular responses
to L-Glu (+47+/-3 mmHg, -68+/-8 bpm vs. +20+/-5 mmHg, -40+/-9 bpm; before vs.
after, n=10, P<0.05). Matched series yielded no vehicle- or time-related
effects. Our findings suggest that a heme oxygenase product, such as carbon
monoxide, may affect NTS glutamatergic neurotransmission to participate in
cardiovascular control. Copyright 1999 Elsevier Science B.V.

PMID: 10196444 [PubMed - indexed for MEDLINE]