Verhaeghe R H
Am J Physiol. 1977 Jul;233(1):H114-21. doi: 10.1152/ajpheart.1977.233.1.H114.
Adenosine depressed norepinephrine contractions of dogs' saphenous vein strips in both the presence and the absence of Ca2+ and after inhibition of calcium influx by verapamil. It antagonized noncompetitively contractions induced by Ca2+ in depolarized strips after alpha-adrenergic blockade. Contractions obtained with acetylcholine were also depressed by adenosine. This depression was not accompanied by an increase in cAMP or a decrease in the elevated cGMP level. Thus the depression of the smooth muscle cell reactivity still occurs in the absence of calcium influx and is not mediated by the cyclic 3',5'-nucleotide system. Adenosine diphosphate and triphosphate, but not adenosine (10(-6) to 10(-4) M), increased the basal tension of resting saphenous strips. This was prevented by removal of calcium from the bath. In contracted strips, lower concentrations of both nucleotides (10(-6) to 10(-5) M) caused relaxation whereas with high concentrations (10(-4) to 10(-3) M) further contraction occurred. Thus, unlike adenosine, the adenine nucleotides facilitate calcium influx.
在存在和不存在Ca2+的情况下，以及在维拉帕米抑制钙内流后，腺苷均可抑制犬隐静脉条带的去甲肾上腺素收缩。在α-肾上腺素能阻断后，它非竞争性地拮抗去极化条带中由Ca2+诱导的收缩。腺苷也可抑制乙酰胆碱引起的收缩。这种抑制并不伴随着cAMP的增加或升高的cGMP水平的降低。因此，平滑肌细胞反应性的抑制在没有钙内流的情况下仍然会发生，并且不是由环3',5'-核苷酸系统介导的。二磷酸腺苷和三磷酸腺苷（而非腺苷，10(-6)至10(-4)M）可增加静息隐静脉条带的基础张力。从浴槽中除去钙可防止这种情况发生。在收缩的条带中，较低浓度的两种核苷酸（10(-6)至10(-5)M）会引起舒张，而高浓度（10(-4)至10(-3)M）则会导致进一步收缩现象。因此，与腺苷不同，腺嘌呤核苷酸促进钙内流。
