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向水合氯醛麻醉的大鼠海马内微量注射肾上腺素α、β受体激动剂,观察其对血压和心率的影响。 海马内注射α受体激动剂可乐宁1.5μg或β受体激动剂异丙肾上腺素1.5μg分别使血压下降36±4％(P<0.001)和25±7％(P<0.01)。可乐宁并可使心率减慢22±4％(P<0.01)。这些作用具有剂量反应关系,并可被相应的α受体颉颃剂ARC_(239)和β_1受体颉颃剂metoprolol所阻断。将上述药物注入海马以外的邻近结构则无效。这些资料说明海马中的儿茶酚胺类神经递质可作用于α和β受体引起降压,作用于α受体使心率减慢。海马头端注射异丙肾上腺素后引起的心加速效应不能被β_1阻断剂Metoprolol阻断。因此,该效应是否有可能通过β_2受体或其它机制,尚有待进一步实验加以证明。
To chloral hydrate anesthetized rat hippocampus microinjection of adrenergic α, β receptor agonists observed its impact on blood pressure and heart rate. Intra-hippocampal injection of 1.5 μg of α-receptor agonist, Clonidine or 1.5 μg of β-agonist, isoproterenol decreased blood pressure by 36 ± 4% (P <0.001) and 25 ± 7% (P <0.01), respectively. Clonidine also slowed heart rate by 22 ± 4% (P <0.01). These effects have a dose-response relationship and are blocked by the corresponding alpha receptor antagonist ARC 239 and the beta 1 receptor antagonist metoprolol. The injection of these drugs into the vicinity of the hippocampus is ineffective. These data suggest that catecholamine neurotransmitters in the hippocampus can act on alpha and beta receptors to cause antihypertension and act on alpha receptors to slow heart rate. Cardiac acceleration induced by isoproterenol injection in the hippocampus can not be blocked by the β_1 blocker Metoprolol. Therefore, whether this effect is likely to pass the β_2 receptor or other mechanisms remains to be demonstrated by further experiments.