Buñag R D, Riley E, Montello M
Am J Physiol. 1976 Dec;231(6):1708-15. doi: 10.1152/ajplegacy.1976.231.6.1708.
Whether or not pressor responsiveness changes in unanesthetized rats during recurrent sympathetic excitation was determined by recording blood pressure and heart rate continuously while the posterior hypothalamus was stimulated repeatedly with constant currents. Because preliminary tests showed that telestimulation with a radio-controlled stimulator produced erratic responses, awake rats were routinely stimulated in a conventional manner by connecting them through wires to a square-wave stimulator. Although tachycardia was the most common chronotropic effect, bradycardia also occurred, and both responses were occasionally seen in the same rat at different times. Inhibition of chronotropic responses by combined pharmacologic blockage with propranolol and atropine did not affect corresponding pressure responses in normotensive rats. Renal and spontaneously hypertensive rats always had larger pressor responses than normotensive ones, and, in spite of individual variations, responsiveness generally remained unaltered during 3-6 h of repeated hypothalamic stimulation. These results indicate that in awake normotensive or hypertensive rats cardiovascular responses to posterior hypothalamic stimulation continue unabated even when stimulation is repeated for hours.
在反复进行交感神经兴奋期间，未麻醉大鼠的升压反应性是否发生变化，是通过在恒定电流反复刺激下丘脑后部的同时连续记录血压和心率来确定的。由于初步试验表明，使用无线电控制刺激器进行远程刺激会产生不稳定的反应，因此，通过电线将清醒大鼠连接到方波刺激器上，以常规方式对其进行刺激。虽然心动过速是最常见的变时效应，但也会出现心动过缓，并且在同一只大鼠的不同时间偶尔会同时出现这两种反应。在正常血压大鼠中，普萘洛尔和阿托品联合药物阻断对变时反应的抑制并不影响相应的压力反应。肾性和自发性高血压大鼠的升压反应总是比正常血压大鼠大，并且，尽管存在个体差异，但在反复刺激下丘脑3至6小时期间，反应性通常保持不变。这些结果表明，在清醒的正常血压或高血压大鼠中，即使连续数小时重复刺激，对下丘脑后部刺激的心血管反应仍不会减弱。
