Canver C C, Cooler S D, Saban R
Division of Cardiothoracic Surgery, Albany Medical College, New York 12208, USA.
J Cardiovasc Surg (Torino). 2000 Aug;41(4):529-32.
The role of internal thoracic artery (ITA) nervous supply has not been previously considered as a potential factor influencing excellent long-term patency of an ITA graft. To define the interaction between the primary afferent neurons and endothelial cells of ITA, we investigated the effects of acute capsaicin administration in vitro on the isometric tension of human ITAs.
Vessels were obtained from patients undergoing coronary bypass or from multi-organ transplant donors. Thirty-three ITA segments (5 mm wide) were suspended as rings between two stainless-steel stir-ups in water-jacketed (37 degrees C) tissue baths. The tissue baths contained 10 ml physiological salt solution (PSS) of the following composition (mM/L): NaCl 119, KCl 4.7, NaH2PO4 1.0, MgCl2 0.5, CaCl2 2.5, NaHCO3 25, and glucose 11, aerated continuously with 95% O2 and 5% CO2. Peptidase inhibitors, phosphoramidon (1 microM) and captopril (1 microM), were added to PSS to decrease peptide degradation. Mechanical responses were measured isometrically and recorded on a polygraph via isometric force transducers. Vessels were preconstricted with submaximal concentrations of norepinephrine. After the tension had stabilized, capsaicin was added cumulatively to the tissue bath. The viability of ITA was verified by its responses to endothelial-dependent (acetylcholine, 1 microM) (n=20) and endothelial-independent (sodium nitroprusside, 10 microM) (n=13) vasodilators.
The exposure of capsaicin (3 microM) to human ITA produced varied effects on ITA irrespective of its endothelium. Capsaicin induced contraction of the ITA smooth muscle in 13 endothelium-intact ITA segments while it produced vasoconstriction in 9 endothelium-denuded ITAs (p=0.6437). In response to capsaicin, relaxation of ITA smooth muscle was observed in 7 ITA rings with endothelium, while vasodilation was present in 4 ITA segments without endothelium (p=0.4099).
Capsaicin-sensitive neurons encircling human ITA produce a neurogenic vasoreactive response independent of ITA endothelial cell integrity.
胸廓内动脉（ITA）神经供应的作用以前未被视为影响ITA移植物长期良好通畅性的潜在因素。为了确定ITA初级传入神经元与内皮细胞之间的相互作用，我们在体外研究了急性给予辣椒素对人ITA等长张力的影响。
血管取自接受冠状动脉搭桥手术的患者或多器官移植供体。将33个ITA节段（5毫米宽）作为环悬挂在恒温（37℃）水浴中的两个不锈钢搅拌器之间。水浴中含有10毫升以下成分（毫摩尔/升）的生理盐溶液（PSS）：氯化钠119、氯化钾4.7、磷酸二氢钠1.0、氯化镁0.5、氯化钙2.5、碳酸氢钠25和葡萄糖11，持续用95%氧气和5%二氧化碳充气。向PSS中加入肽酶抑制剂磷酰胺（1微摩尔）和卡托普利（1微摩尔）以减少肽降解。通过等长力传感器等长测量机械反应，并记录在记录仪上。用亚最大浓度的去甲肾上腺素对血管进行预收缩。张力稳定后，将辣椒素累积加入水浴中。通过ITA对内皮依赖性（乙酰胆碱，1微摩尔）（n = 20）和内皮非依赖性（硝普钠，10微摩尔）（n = 13）血管舒张剂的反应来验证ITA的活力。
辣椒素（3微摩尔）作用于人ITA，无论其内皮情况如何，都会对ITA产生不同影响。辣椒素使13个内皮完整的ITA节段的平滑肌收缩，而使9个内皮剥脱的ITA节段产生血管收缩（p = 0.6437）。在有内皮的7个ITA环中观察到辣椒素使ITA平滑肌舒张，而在无内皮的4个ITA节段中出现血管舒张（p = 0.4099）。
环绕人ITA的辣椒素敏感神经元产生与ITA内皮细胞完整性无关的神经源性血管反应。
