Hamasaki Y, Mojarad M, Said S I
J Appl Physiol Respir Environ Exerc Physiol. 1983 Jun;54(6):1607-11. doi: 10.1152/jappl.1983.54.6.1607.
Vasoactive intestinal peptide (VIP), a potent systemic vasodilator, was recently identified in nerve fibers within the pulmonary arterial wall of cats and other mammals. We have investigated the smooth muscle relaxant action of VIP on isolated strips of kitten pulmonary artery that were placed in a 5-ml bath and precontracted with prostaglandin endoperoxide (PGH2) analogue. The action of VIP was compared with that of acetylcholine, isoproterenol, and prostaglandin E1 (PGE1). The effectiveness of VIP as a relaxant of pulmonary artery, measured as maximal relaxation and expressed in weight equivalents, was 29.9 +/- 2.0 X 10(-2) g in the presence of adrenergic and cholinergic blockers, or 28.8 +/- 4.5 X 10(-2) g in the absence of blockers. This relaxation was similar to that of acetylcholine (30.4 +/- 4.0 X 10(-2) g) and isoproterenol (26.4 +/- 2.2 X 10(-2) g), but smaller than that of PGE1 (41.1 +/- 3.7 X 10(-2) g). Judging by the EC50 or EC10 (effective concentration needed to develop 50 or 10%, respectively, of maximal relaxation), VIP was at least 40 times as potent as acetylcholine, 2,770 times as potent as isoproterenol, and 120 times as potent as PGE1, on a molar basis. The effect of VIP was unaltered in the presence of atropine, propranolol, or phenoxybenzamine in the incubation medium. The findings demonstrate the potent relaxant action of VIP in isolated pulmonary arterial strips and the independence of this action from cholinergic and adrenergic receptors. The results support the possibility that VIP may play an important role in regulating pulmonary vascular tone in kittens.
血管活性肠肽（VIP）是一种强效的全身血管舒张剂，最近在猫和其他哺乳动物的肺动脉壁神经纤维中被发现。我们研究了VIP对置于5毫升浴槽中并用前列腺素内过氧化物（PGH2）类似物预收缩的小猫肺动脉离体条带的平滑肌舒张作用。将VIP的作用与乙酰胆碱、异丙肾上腺素和前列腺素E1（PGE1）的作用进行了比较。以最大舒张度衡量并以重量当量表示，在存在肾上腺素能和胆碱能阻滞剂的情况下，VIP作为肺动脉舒张剂的效力为29.9±2.0×10⁻²克，在不存在阻滞剂的情况下为28.8±4.5×10⁻²克。这种舒张作用与乙酰胆碱（30.4±4.0×10⁻²克）和异丙肾上腺素（26.4±2.2×10⁻²克）相似，但小于PGE1（41.1±3.7×10⁻²克）。从半数有效浓度（EC50）或10%有效浓度（EC10，分别产生最大舒张度的50%或10%所需的有效浓度）判断，按摩尔计算，VIP的效力至少是乙酰胆碱的40倍、异丙肾上腺素的2770倍和PGE1的120倍。在孵育介质中存在阿托品、普萘洛尔或酚苄明的情况下，VIP的作用未改变。这些发现证明了VIP在离体肺动脉条带中具有强效舒张作用，且该作用独立于胆碱能和肾上腺素能受体。结果支持了VIP可能在调节小猫肺血管张力中起重要作用的可能性。
