Fredholm B B
Prog Clin Biol Res. 1984;158:303-30.
It is clear from the previous discussion that caffeine and theophylline can affect practically all parts of the cardiovascular system--directly or indirectly. Whether they will and how significant the effect is likely to be is more uncertain. Even when theophylline, which is generally more potent than caffeine, is infused intravenously, the cardiovascular effects are usually limited. Furthermore, tolerance rapidly develops to the cardiovascular effects of caffeine. Hence, in the general population, caffeine taken in common beverages is unlikely to affect the cardiovascular system very much above the fluctuations brought about by the variable stresses of daily life. However, there may be certain individuals who are uncommonly susceptible. For example, those effects that depend on antagonism of endogenous adenosine (and many of the cardiovascular effects seem to do that directly or indirectly) may be particularly strong in individuals who either have high levels of adenosine or usually many adenosine receptors. These may be the individuals who tolerate caffeine-containing beverages poorly.
从之前的讨论中可以清楚地看出，咖啡因和茶碱实际上可以直接或间接地影响心血管系统的各个部分。它们是否会产生影响以及这种影响可能有多大则更不确定。即使通常比咖啡因更有效的茶碱通过静脉注射，其心血管效应通常也是有限的。此外，对咖啡因的心血管效应会迅速产生耐受性。因此，在普通人群中，普通饮料中所含的咖啡因不太可能对心血管系统产生比日常生活中各种压力所带来的波动更大的影响。然而，可能有某些个体异常敏感。例如，那些依赖于对内源性腺苷的拮抗作用的效应（许多心血管效应似乎直接或间接地依赖于此）在腺苷水平高或通常有许多腺苷受体的个体中可能会特别强烈。这些可能就是那些对含咖啡因饮料耐受性差的个体。
