Effect of ryanodine on adrenergic stimulation in rat smooth muscle cells

兰尼定对大鼠平滑肌细胞的肾上腺素能作用

Norepinephrine(NE)endogenously released following electrical field stimulation(prazosin and TTX sensitive responses),produced a biphasic contraction of the rat vas deferens(RVD).The initial transient contraction was decreased by 30μmol/L ryanodine andμmol/L nifedipine while the secondary component was abolished by 2μmol/L nifedipine but increased by 30μmol/L ryanodine.Exogenously added NE produced biphasic contractions of the RVD.These contractions were inhibited by 2μmol/L nifedipine.Ryanodine(30μmol/L)decreased both phases by about 50%.We conclude that ryanodine binding sites reside in RVD endoplasmic reticulum(ER).There was a lack of uniformity in the effect of ryanodine against different phases of alpha-adrenergic stimulation may be indicative of two modes of stimulation-contraction coupling process related to this stimulation.

电场刺激后释放的内源性去甲肾上腺素可引起大鼠输精管的双相收缩。初始的短暂收缩可被30μmol/L兰尼定和2μmol/L硝苯啶减弱,而后继的收缩部分可被2μmol/L硝苯啶消除,但被30μmol/L兰尼定增强。外加的去甲肾上腺素也可产生输精管的双相收缩,这两相都能被2μmol/L硝苯啶抑制,兰尼定30μmol/L可使两个相的收缩都减弱50%。我们推测兰尼定的结合位点在输精管的内质网。兰尼定对α-肾上腺素能刺激的不同相的作用不一致,表明对α-肾上腺素能的刺激一收缩偶合有两种方式。