Hartmann P E, Whitely J L, Willcox D L
J Physiol. 1984 Feb;347:453-63. doi: 10.1113/jphysiol.1984.sp015075.
The concentration of lactose in plasma was determined in different sows at all phases of their reproductive cycle and related to the compositional changes in mammary secretion during lactogenesis, established lactation and weaning. Lactose was present in low concentrations (3-4 microM) in the blood of virgin sows and pregnant sows up to 107 days of gestation. From day 4 pre-partum to day 1 pre-partum circulating lactose rose gradually to 34.5 +/- 7.7 microM (mean +/- S.E. of mean). Maximal concentrations of 262 +/- 168.4 microM were reached 6 h after parturition. The concentration of lactose in plasma was correlated with the amount of lactose in mammary secretion (r = 0.88, P less than 0.01) at the beginning of farrowing. During established lactation the concentrations of lactose, Na and K in milk, and of lactose in plasma (72-86 microM), were constant. The concentration of lactose in plasma did not vary significantly during periods of suckling, or after stimulation of milk ejection by oxytocin. However, the amount of lactose in plasma rose significantly (P less than 0.02) after the administration of oxytocin if milk ejection was not accompanied by suckling. The mean plasma concentration of lactose began to rise 36 h after weaning to a peak value of 241.8 +/- 53.6 microM at 48 h; thereafter it declined to 10.2 +/- 2.0 microM by 6 days. This study has shown that lactose concentrations in the plasma vary according to the secretory activity of the mammary gland. Its plasma concentration provides an earlier temporal measure of lactogenesis in individual sows than is obtained either from observation or analysis of mammary secretion.
测定了不同母猪在生殖周期各阶段血浆中乳糖的浓度，并将其与泌乳、泌乳确立期和断奶期乳腺分泌物的成分变化相关联。初情期母猪和妊娠至107天的妊娠母猪血液中乳糖浓度较低（3 - 4微摩尔/升）。从产前4天到产前1天，循环乳糖逐渐升高至34.5±7.7微摩尔/升（平均值±平均标准误）。产后6小时达到最高浓度262±168.4微摩尔/升。分娩开始时，血浆中乳糖浓度与乳腺分泌物中乳糖量相关（r = 0.88，P<0.01）。在泌乳确立期，牛奶中乳糖、钠和钾的浓度以及血浆中乳糖的浓度（72 - 86微摩尔/升）保持恒定。在哺乳期间或催产素刺激排乳后，血浆中乳糖浓度没有显著变化。然而，如果排乳时没有哺乳，注射催产素后血浆中乳糖量会显著升高（P<0.02）。断奶后36小时，血浆乳糖平均浓度开始升高，在48小时达到峰值241.8±53.6微摩尔/升；此后到6天时降至10.2±2.0微摩尔/升。本研究表明，血浆中乳糖浓度根据乳腺的分泌活动而变化。与通过观察或分析乳腺分泌物获得的结果相比，其血浆浓度为个体母猪的泌乳开始提供了更早的时间指标。
