Gross P M, Harper A M, Teasdale G M
J Cereb Blood Flow Metab. 1981;1(2):219-25. doi: 10.1038/jcbfm.1981.23.
H2-receptors predominantly mediate pial arteriolar dilatation in response to histamine, but the reaction of pial veins to histamine has not been clearly identified. In anesthetized cats, we examined responses of pial veins and arterioles to perivascular microapplication of histamine and specific histamine H1 and H2 receptor agonists. Arterioles were very sensitive to the H2-receptor agonist impromidine, with significant dilatation (+16%) occurring at concentrations as low as 10(-10) M. Arteriolar responses to H1 receptor stimulation by 2.2-pyridylethylamine were small, even at high concentrations. The order of potency and maximum dilatations found for the receptor agonists were: H2 (43%) greater than histamine (28%) greater than H1 (17%). By contrast, pial veins did not respond to histamine or the receptor agonists. The results indicate that pial venomotor activity to histamine is negligible, and suggest a sparse distribution of histamine receptors on the outer surfaces of pial veins.
H2受体主要介导软脑膜小动脉对组胺的舒张反应，但软脑膜静脉对组胺的反应尚未明确。在麻醉猫中，我们研究了软脑膜静脉和小动脉对血管周围微量应用组胺及特异性组胺H1和H2受体激动剂的反应。小动脉对H2受体激动剂英普咪定非常敏感，低至10（-10）M的浓度即可引起显著舒张（+16%）。即使在高浓度下，2,2-吡啶乙胺对H1受体的刺激引起的小动脉反应也很小。受体激动剂的效价顺序和最大舒张程度为：H2（43%）＞组胺（28%）＞H1（17%）。相比之下，软脑膜静脉对组胺或受体激动剂无反应。结果表明，软脑膜静脉对组胺的舒缩活动可忽略不计，提示组胺受体在软脑膜静脉外表面分布稀疏。
