Excitatory amino acid receptor blockade within the caudal pressor area and rostral ventrolateral medulla alters cardiovascular responses to nucleus raphe obscurus stimulation in rats
| Autor: | N.F. Silva, J. G. P. Pires, H.A. Futuro Neto, M. A. Dantas |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
Male
Bradycardia medicine.medical_specialty Microinjections Physiology Immunology Biophysics Stimulation Biochemistry Nucleus raphe obscurus Excitatory amino acid receptors chemistry.chemical_compound Kynurenic acid Heart Rate Internal medicine Heart rate medicine Animals Ventrolateral medulla Rats Wistar General Pharmacology Toxicology and Pharmaceutics lcsh:QH301-705.5 Microinjection Medulla Oblongata lcsh:R5-920 General Neuroscience Cell Biology General Medicine Rostral ventrolateral medulla Caudal pressor area Electric Stimulation Rats Endocrinology lcsh:Biology (General) chemistry Electrical stimulation Blood pressure medicine.symptom lcsh:Medicine (General) Raphe nuclei Excitatory Amino Acid Antagonists |
| Zdroj: | Brazilian Journal of Medical and Biological Research, Volume: 35, Issue: 10, Pages: 1237-1245, Published: OCT 2002 Brazilian Journal of Medical and Biological Research v.35 n.10 2002 Brazilian Journal of Medical and Biological Research Associação Brasileira de Divulgação Científica (ABDC) instacron:ABDC Brazilian Journal of Medical and Biological Research, Vol 35, Iss 10, Pp 1237-1245 (2002) |
| Popis: | Pressor responses elicited by stimulation of the nucleus raphe obscurus (NRO) depend on the integrity of the rostral ventrolateral medulla (RVLM). Therefore, to test the participation of excitatory amino acid (EAA) receptors in the cardiovascular responses evoked by NRO stimulation (1 ms, 100 Hz, 40-70 microA, for 10 s), the EAA antagonist kynurenic acid (Kyn) was microinjected at different sites in the ventrolateral medullar surface (2.7 nmol/200 nl) of male Wistar rats (270-320 g, N = 39) and NRO stimulation was repeated. The effects of NRO stimulation were: hypertension (deltaMAP = +43 +/- 1 mmHg, P0.01), bradycardia (deltaHR = -30 +/- 7 bpm, P0.01) and apnea. Bilateral microinjection of Kyn into the RVLM, which did not change baseline parameters, almost abolished the bradycardia induced by NRO stimulation (deltaHR = -61 +/- 3 before vs -2 +/- 3 bpm after Kyn, P0.01, N = 7). Unilateral microinjection of Kyn into the CVLM did not change baseline parameters or reduce the pressor response to NRO stimulation (deltaMAP = +46 +/- 5 before vs +48 +/- 5 mmHg after Kyn, N = 6). Kyn bilaterally microinjected into the caudal pressor area reduced blood pressure and heart rate and almost abolished the pressor response to NRO stimulation (deltaMAP = +46 +/- 4 mmHg before vs +4 +/- 2 mmHg after Kyn, P0.01, N = 7). These results indicate that EAA receptors on the medullary ventrolateral surface play a role in the modulation of the cardiovascular responses induced by NRO stimulation, and also suggest that the RVLM participates in the modulation of heart rate responses and that the caudal pressor area modulates the pressor response following NRO stimulation. |
| Databáze: | OpenAIRE |
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