Nakahara H, Nakazawa M, Takeda K, Imai S
Jpn J Pharmacol. 1985 Dec;39(4):487-92. doi: 10.1254/jjp.39.487.
Acute hypotensive effects and the mechanisms of three beta-adrenergic blocking drugs with alpha-blocking activity were studied in comparison with those of prazosin, propranolol and hydralazine in the conscious spontaneously hypertensive rat (SHR). Prazosin lowered the blood pressure dose-dependently and inhibited the pressor response to phenylephrine. Three beta-adrenergic blocking drugs with alpha-blocking activity, labetalol (30 mg/kg), arotinolol (100 mg/kg) and nipradilol (100 mg/kg) also lowered the blood pressure to the same extent as prazosin (0.3 mg/kg), but the inhibition of the pressor response to phenylephrine produced by them was disproportionately slight. Propranolol (100 mg/kg) did not lower the blood pressure. These results suggest that the acute hypotensive effects of three beta-adrenergic blocking drugs with alpha-blocking activity were attributable only partially to the alpha-adrenergic blocking effect; a mechanism or mechanisms other than the alpha-adrenergic blocking effect must be invoked to explain the acute hypotensive effect produced by lower doses of these drugs in the conscious SHR.
在清醒的自发性高血压大鼠（SHR）中，研究了三种具有α阻断活性的β肾上腺素能阻断药物与哌唑嗪、普萘洛尔和肼屈嗪相比的急性降压作用及其机制。哌唑嗪剂量依赖性地降低血压，并抑制对去氧肾上腺素的升压反应。三种具有α阻断活性的β肾上腺素能阻断药物，拉贝洛尔（30mg/kg）、阿罗洛尔（100mg/kg）和尼普地洛（100mg/kg）也能将血压降低到与哌唑嗪（0.3mg/kg）相同的程度，但它们对去氧肾上腺素升压反应的抑制作用相对较小。普萘洛尔（100mg/kg）未降低血压。这些结果表明，三种具有α阻断活性的β肾上腺素能阻断药物的急性降压作用仅部分归因于α肾上腺素能阻断作用；必须引入α肾上腺素能阻断作用以外的一种或多种机制来解释这些药物在清醒SHR中较低剂量产生的急性降压作用。
