Sherwood O D, Crnekovic V E, Gordon W L, Rutherford J E
Endocrinology. 1980 Sep;107(3):691-8. doi: 10.1210/endo-107-3-691.
Relaxin immunoactivaity concentrations in the peripheral sera been measured during pregnancy and parturition in rats with a homologous rat relaxin RIA. Relaxin was not detected until day 10 of pregnancy (day 10). Relaxin levels increased markedly over the next 4 days and generally ranged between 50-100 ng/ml from days 14-20. A prepartum surge in relaxin levels, which appeared to be associated with the photoperiod, occurred on day 21 in unanesthetized rats bled via indwelling jugular cannulas. Mean relaxin levels in these animals increased sharply from less than 80 ng/ml on day 20 to approximately 140 ng/ml at 1400 h on day 21 and declined to less than 60 ng/ml during the 12-24 h preceding parturition. The prepartum surge in relaxin immunoactivity may be associated with luteolysis, since there was an accelerated decline in progesterone concentrations concurrent with the prepartum relaxin surg. Rats also experienced a surge in relaxin concentrations during parturition. The mean maximal level of relaxin during parturition was approximately 180 ng/ml. The rate of decline of rat relaxin immunoactivity levels after bilateral ovariectomy on day 21 demonstrated characteristics of a multiexponential curve. The mean clearance t 1/2 from 0-30 min was 22 +/- 3 min (+/- SEM), and the mean t 1/2 from 30-180 min was 56 +/- 7 min (+/0 SEM).
用同源大鼠松弛素放射免疫分析法测定了大鼠妊娠和分娩期间外周血清中的松弛素免疫活性浓度。直到妊娠第10天（第10天）才检测到松弛素。在接下来的4天里，松弛素水平显著升高，从第14天到第20天，其水平一般在50-100 ng/ml之间。在未麻醉、通过留置颈静脉插管采血的大鼠中，第21天出现了与光周期相关的产前松弛素水平激增。这些动物的平均松弛素水平从第20天的不到80 ng/ml急剧增加到第21天1400时的约140 ng/ml，并在分娩前12-24小时内降至不到60 ng/ml。产前松弛素免疫活性的激增可能与黄体溶解有关，因为在产前松弛素激增的同时，孕酮浓度加速下降。大鼠在分娩期间也出现了松弛素浓度的激增。分娩期间松弛素的平均最高水平约为180 ng/ml。第21天双侧卵巢切除术后大鼠松弛素免疫活性水平的下降速率呈现多指数曲线特征。0-30分钟的平均清除半衰期为22±-3分钟（±标准误），30-180分钟的平均半衰期为56±-7分钟（±标准误）。
