Bruce C, Yates D H, Thomas P S
Faculty of Medicine, UNSW and Department of Respiratory Medicine, Prince of Wales Hospital, Sydney, NSW 2031, Australia.
Thorax. 2002 Apr;57(4):361-3. doi: 10.1136/thorax.57.4.361.
Caffeine is known to inhibit phosphodiesterases, to mobilise intracellular calcium, and to act as an antagonist at adenosine receptors, all of which can potentially alter nitric oxide (NO) production. It was therefore hypothesised that caffeine may alter exhaled NO (eNO) levels.
In a randomised, single blind, crossover manner, 12 normal subjects consumed either (1) coffee and a placebo capsule, (2) decaffeinated coffee and a capsule of 200 mg caffeine, or (3) decaffeinated coffee and a placebo capsule. Serum caffeine levels were measured at baseline and 1 hour later. Exhaled NO levels were also measured at baseline and each hour for 4 hours.
A significant percentage fall in mean (SE) eNO from baseline was seen 1 hour after either caffeinated coffee or a caffeine capsule when compared with placebo (13.5 (4.0)%, p=0.009 and 19.0 (3.8)%, p=0.001, respectively).
Caffeine causes a significant decrease in eNO which will need to be considered when designing trials to measure eNO levels. The mechanism may be via adenosine receptor antagonism or by altering levels of cGMP.
已知咖啡因可抑制磷酸二酯酶、动员细胞内钙，并作为腺苷受体拮抗剂发挥作用，所有这些都可能潜在地改变一氧化氮（NO）的生成。因此，有人提出假设，咖啡因可能会改变呼出一氧化氮（eNO）水平。
12名正常受试者以随机、单盲、交叉方式分别摄入：（1）咖啡和一粒安慰剂胶囊；（2）脱咖啡因咖啡和一粒200毫克咖啡因胶囊；或（3）脱咖啡因咖啡和一粒安慰剂胶囊。在基线和1小时后测量血清咖啡因水平。在基线以及之后4小时内每小时测量呼出一氧化氮水平。
与安慰剂相比，摄入含咖啡因咖啡或咖啡因胶囊1小时后，平均（标准误）eNO较基线有显著百分比下降（分别为13.5（4.0）%，p = 0.009和19.0（3.8）%，p = 0.001）。
咖啡因会使eNO显著降低，在设计测量eNO水平的试验时需要考虑这一点。其机制可能是通过腺苷受体拮抗作用或改变环磷酸鸟苷（cGMP）水平。
