Summary
The cardiovascular effects of selective alpha1 and alpha2 agonists and antagonists injected into the nucleus tractus solitarii (NTS) were studied in urethane-anesthetized rats. Methoxamine (0.3–3 μg) injected bilaterally into the NTS caused a dose-dependent increase in blood pressure and heart rate. Phenylephrine (6 μg) and an imidazolidine derivative St 587 (3 μg) similarly injected also produced an increase in blood pressure, whereas a-methylnoradrenaline and an azepine derivative B-HT 920 (1 and 3 μg) caused a decrease in blood pressure and heart rate. The pressor response to methoxamine (1 μg) was markedly inhibited by prazosin (0.3 pg) injected into the same sites or hexamethionum (25 mg/kg, i. v.). Prazosin (0.3 μg) alone injected bilaterally into the NTS did not affect the blood pressure, while yohimbine (0.1 μg) similarly injected increased the pressure. These results suggest that in the rat NTS there exist alpha1 adrenoceptors responsible for an increase in arterial pressure. The NTS alpha2 adrenoceptors seem to be involved in the tonic regulation of arterial pressure.
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Kubo, T., Kihara, M., Hata, H. et al. Cardiovascular effects in rats of alpha1 and alpha2 adrenergic agents injected into the nucleus tractus solitarii. Naunyn-Schmiedeberg's Arch Pharmacol 335, 274–277 (1987). https://doi.org/10.1007/BF00172796
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DOI: https://doi.org/10.1007/BF00172796