Navegando por Palavras-chave "blood pressure, arterial"

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    Excitatory effects of nitric oxide within the rostral ventrolateral medulla of freely moving rats
    (Amer Heart Assoc, 1997-09-01) Pinge, Marli Cardoso Martins [UNIFESP]; Passy, Izabel Baraldi [UNIFESP]; Lopes, Oswaldo Ubriaco [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The aim of the present study was to examine the participation of NO in the rostral ventrolateral medulla (RVLM) of freely moving rats. We utilized NO donors and L-arginine, which were microinjected into the RVLM. Unilateral microinjection (100 nL) of 2.5 nmol sodium nitroprusside produced a biphasic response consisting of an initial, rapid increase in arterial pressure (AP) from 125+/-5 to 161+/-8 mm Hg (P<.01) and a second, long-lasting response with a progressive increase in AP (maximum Delta peak, 34+/-9 mm Hg; P<.01). Another NO donor, S-nitroso-N-acetylpenicillamine (SNAP; 2.5 nmol), also produced immediate hypertension from 118+/-5 mm Hg to 168+/-7 mm Hg (P<.01) but without the second, long-lasting response. L-Arginine (5, 24, and 140 nmol) produced a gradual increase in AP. L-Glutamate (5 nmol) microinjected into the RVLM produced an increase in AP from 122+/-9 mm Hg to 171+/-8 mm Hg (P<.01) and bradycardia from 342+/-10 to 315+/-8 beats/min. This AP response was significantly attenuated, from 115+/-7 to 128+/-9 mm Hg (P<.05), after microinjection of methylene blue (3 nmol) without alterations In heart rate. These results indicate that NO may have an excitatory effect on the RVLM of freely moving rats, probably in association with glutamatergic synapses via cGMP mechanisms.
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    Nitric oxide-dependent guanylyl cyclase participates in the glutamatergic neurotransmission within the rostral ventrolateral medulla of awake rats
    (Lippincott Williams & Wilkins, 1999-10-01) Pinge, Marli Cardoso Martins [UNIFESP]; Araujo, G. C.; Lopes, Oswaldo Ubriaco [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    A well-known action of nitric oxide (NO) is to stimulate the soluble form of guanylyl cyclase, evoking an accumulation of cyclic GMP in target cells. The aim of the present study was to examine the effects of inhibition of guanylyl cyclase dependent on NO during cardiovascular responses induced by L-glutamate and S-nitrosoglutathione (SNOG) microinjected into the rostral ventrolateral medulla (RVLM) of awake rats. Three days before the experiments, adult male Wistar rats (280 to 320 g) were anesthetized for implantation of guide cannulas to the desired stereotaxic position (AP=-2.5 mm, L=1.8 mm) in relation to lambda. The cannulas were fixed to the skull with acrylic cement. Twenty-four hours before the experiments, a femoral artery and vein were cannulated for recording arterial pressure (AP) and heart rate (HR) and injection of anesthetic. Unilateral microinjections (100 nL) of L-glutamate (5 nmol/L) and SNOG (2.5 nmol/L) were made into the histologically confirmed RVLM. The cardiovascular responses to these drugs were evaluated before and after microinjection (3 nmol/L, 200 nL) of either methylene blue or oxodiazoloquinoxaline (ODQ). The hypertensive effect of L-glutamate was attenuated by 74% after methylene blue (Delta A=49+/-8 to 13+/-4 mm Hg) and by 80.5% after ODQ (Delta AP=30+/-2 to 6+/-2 mm HS) The increase in AP produced by SNOG was fully blocked by ODQ (Delta AP=39+/-8 to 1+/-2 mm Hg). These data indicate that cyclic GMP mechanisms have a key role in glutamatergic neurotransmission in the RVLM of awake rats, and it is most probable that NO participates: in this response.