Sanders K M
Am J Physiol. 1978 Feb;234(2):E209-12. doi: 10.1152/ajpendo.1978.234.2.E209.
The effects of endogenous prostaglandin E (PGE) on the contractile activity of isolated cat ileal muscle rings were studied. Force development in circularly oriented muscle fibers were recorded. The muscles contained a mean basal PGE concentration of 1 +/- 0.6 ng PGE per g wet wt (mean +/- SE) as measured by radioimmunoassay. Acetylcholine (ACh) or elevated potassium caused contractions and enhanced PGE concentration (P less than 0.05). Removing Ca2+ from high potassium solutions blocked contraction, but PGE concentration still increased (P less than 0.02). The prostaglandin synthetase inhibitors, indomethacin and 5,8,11,14-eicosatetraenoic acid (ETA) reduced PGE concentration in muscles (less than 50 pg PGE per g muscle) and increased the magnitude of contractions induced by either ACh or elevated potassium. Spontaneous contractions were observed in many tissues after inhibition of PGE synthesis. In conclusion, endogenous PGE limits spontaneous and depolarization-induced muscular activity in cat ileal circular muscle. Synthesis of PGE was increased by depolarizing stimuli whether or not contractions were blocked by the removal of external calcium.
研究了内源性前列腺素E（PGE）对离体猫回肠肌环收缩活性的影响。记录了环形肌纤维的力量发展情况。通过放射免疫测定法测得，肌肉中PGE的平均基础浓度为每克湿重1±0.6纳克PGE（平均值±标准误）。乙酰胆碱（ACh）或高钾可引起收缩并提高PGE浓度（P<0.05）。从高钾溶液中去除Ca2+可阻断收缩，但PGE浓度仍会升高（P<0.02）。前列腺素合成酶抑制剂吲哚美辛和5,8,11,14-二十碳四烯酸（ETA）可降低肌肉中的PGE浓度（每克肌肉低于50皮克PGE），并增加由ACh或高钾诱导的收缩幅度。在抑制PGE合成后，许多组织中观察到自发收缩。总之，内源性PGE限制了猫回肠环形肌的自发和去极化诱导的肌肉活动。无论收缩是否因去除细胞外钙而被阻断，去极化刺激均可增加PGE的合成。
