Nassar B A, Horrobin D F, Tynan M, Manku M S, Davies P A
Endocrinology. 1975 Oct;97(4):1008-13. doi: 10.1210/endo-97-4-1008.
Rabbit hearts perfused by the Langendorff technique were studied. The addition of ovine prolactin (NIH-P-S-10) to the perfusate in a concentration of 50 ng/ml produced rapid increases in both the amplitude and rate of contraction in 33 adult male hearts studied in winter. Prepubertal male animals showed no response, and only 1 out of 12 adult females responded. Pretreatment for 10 days with 2.5 mg/day testosterone propionate led to minimal inotropic but not chronotropic responses in 2 out of 4 prepubertal males and 2 out of 4 adult females to prolactin. Clear responses to prolactin were seen in 5 adult males pretreated with reserpine. Propanolol consistently reversed both the inotropic and chronotropic actions of prolactin. The original experiments were performed in January and February. When tested in May, adult males failed to respond to prolactin and this situation, persisted until October when responsiveness again appeared. The same prolactin preparation and procedures were used throughout indicating that the changes must have been due to seasonal variations in the cardiac responsiveness to the hormone.
对采用Langendorff技术灌注的兔心脏进行了研究。在冬季研究的33只成年雄性心脏中，向灌注液中添加浓度为50纳克/毫升的绵羊催乳素（NIH - P - S - 10）可使收缩幅度和速率迅速增加。青春期前的雄性动物无反应，12只成年雌性动物中只有1只产生反应。每天用2.5毫克丙酸睾酮预处理10天，导致4只青春期前雄性动物中的2只以及4只成年雌性动物中的2只对催乳素产生最小的变力反应，但无变时反应。在5只用利血平预处理的成年雄性动物中观察到对催乳素的明显反应。普萘洛尔始终能逆转催乳素的变力和变时作用。最初的实验在1月和2月进行。5月进行测试时，成年雄性动物对催乳素无反应，这种情况一直持续到10月，此时反应性再次出现。整个过程使用相同的催乳素制剂和操作程序，这表明这些变化一定是由于心脏对该激素反应性的季节性变化所致。
