Navegando por Palavras-chave "CAROTID OCCLUSION"

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    DECREASED SUSCEPTIBILITY TO SEIZURES INDUCED BY BICUCULLINE AFTER TRANSIENT BILATERAL CLAMPING of the CAROTID ARTERIES in RATS
    (Springer, 1991-01-01) Sieklucka, M.; Bortolotto, Z.; Heim, C.; Block, F.; Sontag, K. H.; UNIV GOTTINGEN; MAX PLANCK INST EXPTL MED; INST CLIN PATHOL; Universidade Federal de São Paulo (UNIFESP)
    Rats were exposed for 24 min to bilateral clamping of the common carotid arteries (BCCA) in pentobarbital anaesthesia. 14 days later the animals were subjected to subcutaneous injection of (+)-bicuculline (3 or 4 mg/kg). A significantly decreased susceptibility to bicuculline-induced seizures could be observed in BCCA treated rats compared with sham operated controls. It is suggested that BCCA treatment protects animals against status epilepticus and lethal toxicity produced by bicuculline. Electrographic recordings of the BCCA animals revealed no ictal activity within 1 h after bicuculline injection. An analysis of the GABA content showed a significant increase in the hippocampus (HPC), frontal cortex (FCX), parietal cortex and substantia nigra in BCCA animals compared with controls. It is therefore possible that an increase in GABA content postsynaptically counteracts the GABA(A) antagonistic effect of bicuculline in BCCA animals thus preventing the normal seizure inducing effect of this substance.
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    A FALL in ARTERIAL BLOOD-PRESSURE PRODUCED BY INHIBITION of the CAUDALMOST VENTROLATERAL MEDULLA - the CAUDAL PRESSER AREA
    (Elsevier B.V., 1994-11-01) Possas, O. S.; Campos, R. R.; Cravo, S. L.; Lopes, O. U.; Guertzenstein, P. G.; Universidade Federal de São Paulo (UNIFESP)
    The caudal edge of the ventrolateral medulla was mapped to localize sites where microinjections of L-glutamate (L-glu) produce presser responses in paralyzed and artificially ventilated urethane-anesthetized rats. Presser responses ranging from 15 to 65 mmHg were obtained when L-Glu (0.25 M, 200 nl) was microinjected in the ventral medullary surface within an area localized between the rootlets of the XII and first cervical nerves, lateral to the pyramids and just medial to the spinal roots of the XI cranial nerve. This area has been called the caudal presser area (CPA). Inhibition of the CPA by microinjection of GABA or glycine resulted in marked falls (15-45 mmHg) of arterial blood pressure (AP). Hypotension in response to CPA inhibition was also obtained in unanesthetized decerebrate animals. Cardiovascular responses to CPA stimulation or inhibition depend on the activity of neurons in the rostral ventrolateral medulla (RVLM). During hypotension provoked by RVLM inhibition, presser responses to CPA stimulation were abolished. Conversely, presser responses to RVLM stimulation were maintained during hypotension produced by inhibition of CPA, Presser response to bilateral carotid occlusion were not reduced by CPA inhibition. We conclude that cells in the caudal most ventrolateral medulla exert a tonic presser activity that contributes to maintenance of basal levels of the vasomotor tone and arterial blood pressure, its inhibition, however, does not prevent the presser response to carotid occlusion.