Johns R A, Peach M J
Department of Anesthesiology, University of Virginia Medical Center, Charlottesville.
J Pharmacol Exp Ther. 1988 Mar;244(3):859-65.
The alkylating agent para-bromophenacyl bromide (PBPB) has been reported to block endothelium-dependent relaxation of arteries, presumably by inhibiting phospholipase in the endothelium. We have investigated the site of action of PBPB-induced inhibition of melittin (MEL)- and bradykinin (BK)-stimulated endothelium-dependent relaxation and vascular smooth muscle (VSM) cyclic GMP (cGMP) accumulation. Studies were performed using short-term co-cultures of bovine pulmonary artery endothelial cells (EC) grown on microcarrier beads and rat aortic VSM. The culture system allowed separate pretreatment of ECs and VSM cells with PBPB (3 X 10(-5) M) before placement of the two cell types in co-culture. Because PBPB is an alkylating agent, it was felt that any blockade would endure after washout. Intracellular (VSM) concentrations of cGMP rose in response to MEL or BK stimulation only when EC were present, and were not decreased when only the EC had been pretreated with PBPB. cGMP accumulation induced by MEL or BK was significantly (P less than .01) inhibited in co-cultures where either the VSM alone or VSM and EC combined were pretreated with PBPB. The PBPB pretreatment adequately blocked EC phospholipase activity as measured by attenuation of the release of [3H]arachidonate from prelabeled EC by MEL. In parallel studies, when endothelium-derived relaxing factor was transferred by superfusion of EC to denuded rabbit aortic rings contracted with phenylephrine and pretreated with PBPB, the relaxation response induced by MEL or BK was inhibited. Similarly, when endothelium-derived relaxing factor was transferred to wells of cultured VSM pretreated with PBPB, cGMP accumulation was inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)
据报道，烷基化剂对溴苯甲酰溴（PBPB）可阻断动脉的内皮依赖性舒张，推测是通过抑制内皮中的磷脂酶来实现的。我们研究了PBPB诱导的对蜂毒肽（MEL）和缓激肽（BK）刺激的内皮依赖性舒张及血管平滑肌（VSM）环磷酸鸟苷（cGMP）积累的抑制作用位点。研究采用微载体珠上培养的牛肺动脉内皮细胞（EC）与大鼠主动脉VSM的短期共培养体系。该培养系统允许在将两种细胞类型共培养之前，先用PBPB（3×10⁻⁵ M）分别预处理EC和VSM细胞。由于PBPB是一种烷基化剂，人们认为任何阻断作用在冲洗后仍会持续。仅当存在EC时，VSM细胞内cGMP浓度才会因MEL或BK刺激而升高，且仅对EC进行PBPB预处理时，cGMP浓度不会降低。在单独对VSM或VSM与EC联合进行PBPB预处理的共培养体系中，MEL或BK诱导的cGMP积累受到显著抑制（P＜0.01）。通过MEL对预先标记的EC中[³H]花生四烯酸释放的衰减来衡量，PBPB预处理充分阻断了EC磷脂酶活性。在平行研究中，当通过将EC的超滤液转移到用苯肾上腺素收缩并经PBPB预处理的去内皮兔主动脉环上，来传递内皮衍生舒张因子时，MEL或BK诱导的舒张反应受到抑制。同样，当将内皮衍生舒张因子转移到经PBPB预处理的培养VSM孔中时，cGMP积累也受到抑制。（摘要截短于250字）
