Ishizawa M
Prostaglandins. 1983 Aug;26(2):175-86. doi: 10.1016/0090-6980(83)90086-2.
Contractile effects of PGD2 and PGF2 alpha on mechanical and electrical activities were investigated in longitudinal and circular muscles of the guinea-pig isolated proximal colon. PGD2 and PGF2 alpha (1 microM)-induced contractions were reduced with a decrease in external Ca ion concentration and were prevented at zero Ca(EGTA 1 mM) in both muscles. In electrical activities recorded by the single sucrose gap method, PGD2 and PGF2 alpha (1 microM) increased the frequency of spike generation on the slow waves in both muscles. Verapamil (10 microM), a Ca antagonist, blocked spontaneous and PG-induced spike activities with little effect on the slow waves in both muscles. Verapamil markedly reduced the contractions to PGs in the longitudinal muscle, but not in the circular muscle. The results suggest that PGD2 and PGF2 alpha produced contractions which may depend largely on an increase in the inward Ca current of the spikes in longitudinal muscle, and may depend both on a release of Ca from the Ca sequestration in the cell, and on a spike-dependent Ca influx in circular muscle of the guinea-pig colon.
在豚鼠离体近端结肠的纵行肌和环行肌中，研究了前列腺素D2（PGD2）和前列腺素F2α（PGF2α）对机械和电活动的收缩作用。随着细胞外钙离子浓度的降低，PGD2和PGF2α（1微摩尔）诱导的收缩减弱，且在两种肌肉中，当钙离子浓度为零时（乙二醇双四乙酸1毫摩尔）收缩被抑制。在用单蔗糖间隙法记录的电活动中，PGD2和PGF2α（1微摩尔）增加了两种肌肉慢波上的锋电位发放频率。钙拮抗剂维拉帕米（10微摩尔）阻断了自发的和PG诱导的锋电位活动，对两种肌肉的慢波影响很小。维拉帕米显著降低了纵行肌对PGs的收缩，但对环行肌没有影响。结果表明，PGD2和PGF2α产生的收缩可能在很大程度上依赖于纵行肌锋电位内向钙电流的增加，并且可能既依赖于细胞内钙库中钙的释放，也依赖于豚鼠结肠环行肌中依赖锋电位的钙内流。
