Freetly H C, Ferrell C L
U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933.
J Anim Sci. 1994 Aug;72(8):2107-12. doi: 10.2527/1994.7282107x.
The objective of this study was to determine whether chronic nutritional treatment influences progesterone (P4) metabolism by splanchnic tissues and to develop a mathematical model of P4 metabolism in ewes. Five ovariectomized (ovx), multiparous ewes were assigned to a high feed intake and five multiparous ovx ewes were assigned to a low feed intake. The ewes with high feed intake received daily ME intakes of 99 kcal/BWkg.75, and the ewes with low intake received daily ME intakes of 63 kcal/BWkg.75. Catheters were placed surgically in the abdominal aorta, the portal vein, a branch of the hepatic vein, and a mesenteric vein. Blood and plasma flows across visceral organs were determined by marker dilution (p-aminohippuric acid), and P4 was determined with a RIA. The net splanchnic P4 flux and oxygen (O2) consumption were determined during five rates of P4 infusion into the jugular vein (112, 224, 449, 897, and 1,795 micrograms/h). Splanchnic O2 consumption was greater (P = .05) in the ewes with high feed intake. Net splanchnic P4 flux did not differ (P > .10) between nutritional treatments. The correlation between net splanchnic P4 flux and O2 consumption did not differ from zero (P = .69). Net splanchnic P4 flux was related linearly to plasma arterial P4 concentration. Splanchnic tissue clearance rate was 18% of the infusion rate. The behavior of the P4 model indicates that whole-body P4 metabolism is the sum of first-order kinetic reactions. The data indicate that splanchnic clearance of P4 is not affected by nutritional status.
本研究的目的是确定长期营养治疗是否会影响内脏组织对孕酮（P4）的代谢，并建立一个母羊P4代谢的数学模型。将五只经产去卵巢（ovx）母羊分配到高采食量组，五只经产ovx母羊分配到低采食量组。高采食量的母羊每日代谢能摄入量为99千卡/体重千克^0.75，低采食量的母羊每日代谢能摄入量为63千卡/体重千克^0.75。通过手术将导管置于腹主动脉、门静脉、肝静脉分支和肠系膜静脉中。通过标记物稀释法（对氨基马尿酸）测定流经内脏器官的血液和血浆流量，并用放射免疫分析法测定P4。在以五种速率（112、224、449、897和1795微克/小时）向颈静脉输注P4期间，测定内脏P4的净通量和氧（O2）消耗量。高采食量的母羊内脏O2消耗量更大（P = 0.05）。营养处理之间内脏P4的净通量没有差异（P > 0.10）。内脏P4净通量与O2消耗量之间的相关性与零无差异（P = 0.69）。内脏P4净通量与血浆动脉P4浓度呈线性相关。内脏组织清除率为输注速率的18%。P4模型的行为表明，全身P4代谢是一级动力学反应的总和。数据表明，P4的内脏清除率不受营养状况的影响。
