Montes Felix R, Cabrera Mariana, Delgadillo Alexandra, Salgar Carlos, Echeverri Dario
Vascular Function Laboratory, Fundación Cardio Infantil - Instituto de Cardiología, Universidad del Rosario, Calle 163A # 13B-60, Bogotá, Colombia.
Vascul Pharmacol. 2009 Mar-Apr;50(3-4):132-6. doi: 10.1016/j.vph.2008.11.002. Epub 2008 Nov 24.
There is little information about the direct effect of caffeine in human blood vessels. The purpose of this study was to evaluate the direct vascular effect of caffeine on human internal mammary artery (IMA) and the involvement of potassium channels in this response. Segments of IMA were obtained from 29 patients who underwent coronary artery bypass graft surgery. They were cut into rings, suspended between two wire hooks in organ bath chambers and constricted submaximally with norepinephrine. Caffeine (3.16x10(-9) to 10(-4) mol/L) was added in a cumulative fashion to rings with or without functional endothelium and concentration response curves were constructed. The response to caffeine was also evaluated after incubation with adenosine 3',5'-triphosphate (ATP)-dependent potassium channel blocker glibenclamide, voltage-dependent potassium channel blocker 4-aminopyridine and large-conductance calcium-activated potassium channel inhibitor tetraethylammonium. Caffeine produced a potent, concentration-dependent relaxation of IMA. The relaxant responses did not differ significantly between endothelium-intact and endothelium-denuded preparations. Incubation with different potassium channel inhibitors (glibenclamide, 4-aminopyridine and tetraethylammonium) did not cause significant alterations in the relaxant responses to caffeine. These results suggest that the vasodilatory response to caffeine in human IMA is independent of endothelial function and is not mediated by potassium channels.
关于咖啡因对人体血管的直接作用，目前所知甚少。本研究的目的是评估咖啡因对人乳内动脉（IMA）的直接血管效应以及钾通道在该反应中的作用。IMA节段取自29例行冠状动脉旁路移植术的患者。将其切成环，悬挂在器官浴槽中的两个金属丝钩之间，并用去甲肾上腺素进行亚最大收缩。将咖啡因（3.16×10⁻⁹至10⁻⁴mol/L）以累积方式添加到有或无功能性内皮的环中，并构建浓度反应曲线。在用腺苷3',5'-三磷酸（ATP）依赖性钾通道阻滞剂格列本脲、电压依赖性钾通道阻滞剂4-氨基吡啶和大电导钙激活钾通道抑制剂四乙铵孵育后，也评估了对咖啡因的反应。咖啡因对IMA产生了强大的、浓度依赖性的舒张作用。在内皮完整和内皮剥脱的制剂之间，舒张反应没有显著差异。用不同的钾通道抑制剂（格列本脲、4-氨基吡啶和四乙铵）孵育不会导致对咖啡因的舒张反应发生显著改变。这些结果表明，人IMA对咖啡因的血管舒张反应独立于内皮功能，且不由钾通道介导。
