δ-氨基乙酰丙酸对家兔离体小肠收缩活动的影响。肾上腺素能受体的作用。

Effects of delta-aminolaevulinic acid on contractile activity in the isolated small intestine of the rabbit. Role of adrenergic receptors.

作者信息

Cutler M G, McLaughlin M, McNeil E, Moore M R

出版信息

Neuropharmacology. 1985 Oct;24(10):1005-9. doi: 10.1016/0028-3908(85)90129-7.

Abstract

The porphyrin precursor, delta-aminolaevulinic acid (ALA) at concentrations of 0.23-7.6 mM caused dose-dependent inhibition of spontaneous contractions in isolated preparations of rabbit small intestine, suspended in Ringer-Locke solution. Contractions which returned after inhibition from 3.8 and 7.6mM ALA showed increased amplitude and from 7.6 mM ALA a reduction in rate. Pretreatment with prazosin (10(-7) M) significantly reduced the duration of inhibition exerted by 3.8 and 7.6 mM ALA and also the amplitude of contractions returning after this inhibition. Pretreatment with yohimbine (10(-6) M) and propranolol (7 X 10(-6) M) had no significant effects. Blocking of the release of noradrenaline in preparations by incubation with 6-hydroxydopamine (10(-3) M) or guanethidine (1.5 X 10(-5) M) did not prevent the inhibitory effects of ALA. The alpha 1 agonist, cirazoline (10(-5) M), inhibited contractile activity. This effect was blocked by prazosin (10(-7) M). The alpha 2 agonist, guanoxabenz (10(-5) M) had no detectable effect, in the presence of prazosin, to block any residual alpha 1 actions. It is concluded that alpha 1 receptors mediate inhibitory effects in this preparation and that ALA appears to have direct effects upon these receptors.

摘要

卟啉前体δ-氨基乙酰丙酸（ALA）浓度在0.23 - 7.6 mM时，对悬浮于林格 - 洛克溶液中的兔小肠离体标本的自发收缩产生剂量依赖性抑制作用。在3.8 mM和7.6 mM ALA抑制后恢复的收缩，其幅度增加，而在7.6 mM ALA作用下收缩频率降低。用哌唑嗪（10⁻⁷ M）预处理可显著缩短3.8 mM和7.6 mM ALA的抑制持续时间，以及抑制后恢复的收缩幅度。用育亨宾（10⁻⁶ M）和普萘洛尔（7×10⁻⁶ M）预处理无显著影响。通过与6 - 羟基多巴胺（10⁻³ M）或胍乙啶（1.5×10⁻⁵ M）孵育来阻断标本中去甲肾上腺素的释放，并不能阻止ALA的抑制作用。α₁激动剂可乐唑啉（10⁻⁵ M）抑制收缩活性。此作用被哌唑嗪（10⁻⁷ M）阻断。在存在哌唑嗪的情况下，α₂激动剂胍那苄（10⁻⁵ M）未显示出可检测到的作用，无法阻断任何残留的α₁作用。结论是α₁受体介导该标本中的抑制作用，且ALA似乎对这些受体有直接作用。