Morán J M, Mahedero G, Salas J, Ribeiro J M, Mariñõ E, Vinagre L M
Department of Surgery, Universidad de Extremadura, Badajoz, Españã.
JPEN J Parenter Enteral Nutr. 1998 Mar-Apr;22(2):72-6. doi: 10.1177/014860719802200272.
The aim of this work was to study the serum bioavailability of glucose and alanine after bolus injection into the peritoneal cavity in Wistar rats and to determine the influence of their metabolism on the rate of absorption of these nutrients.
A group of animals (n = 14) was infused intraperitioneally (i.p.) or i.v. with 2 microCi of nonmetabolizable L-[1-14C] glucose diluted in 5 mL of 5% D-glucose/250 g body wt, after which plasma radioactivity was determined. A second group of animals (n = 14) received, either i.p. or i.v., 3 microCi of nonmetabolizable D-[U-14C] alanine diluted in 2 mL of an iso-os-molar L-amino acid solution/250 g body wt, after which both plasma radioactivity and L-alanine concentration were determined. The constants of absorption from peritoneal cavity (Ka) and elimination from plasma (Ke) and the serum absolute bioavailability (BA(a)) after 8 h were calculated assuming a bicompartment pharmacokinetic model.
L-glucose: Ka = 3.05 +/- 0.97 h-1; Ke = 0.40 +/- 0.12 h-1; BA(a) = 94% +/- 4%. D-alanine: Ka = 1.08 +/- 0.40 h-1; Ke = 0.11 +/- 0.06 h-1; BAa = 90% +/- 11%. L-alanine: Ka = 1.75 +/- 0.273 h-1; Ke = 0.02 +/- 0.01 h-1; BA(a) = 99% +/- 1%. No hyperglycemia, hypoglycemia, or glycosuria appeared in any case.
The absorption rate from peritoneal cavity is nearly 10-fold higher than the elimination rate from plasma for the three substrates. Eight hours after i.p. injection an absolute bioavailability almost as high as after i.v. injection (i.e., close to 100%) was achieved. The metabolism of the nutrients seems to help the peritoneal absorption, as L-alanine is better absorbed then D-alanine. These results show that upon i.p. injection the studied nutrients are almost completely absorbed in a short period of time without hyperglycemia or neoglucogenesis and so suggest that their administration may be a feasible approach to feeding patients receiving peritoneal dialysis. This model could be applied to other compounds, such as peptides and disaccharides.
本研究旨在探讨Wistar大鼠腹腔内注射葡萄糖和丙氨酸后血清中的生物利用度，并确定其代谢对这些营养素吸收速率的影响。
一组动物（n = 14）经腹腔内（i.p.）或静脉内（i.v.）注射稀释于5 mL 5% D - 葡萄糖/250 g体重中的2微居里不可代谢的L - [1 - 14C]葡萄糖，之后测定血浆放射性。第二组动物（n = 14）经腹腔内或静脉内注射稀释于2 mL等渗L - 氨基酸溶液/250 g体重中的3微居里不可代谢的D - [U - 14C]丙氨酸，之后测定血浆放射性和L - 丙氨酸浓度。假设为二室药代动力学模型，计算腹腔吸收常数（Ka）、血浆消除常数（Ke）以及8小时后的血清绝对生物利用度（BA(a)）。
L - 葡萄糖：Ka = 3.05 ± 0.97 h-1；Ke = 0.40 ± 0.12 h-1；BA(a) = 94% ± 4%。D - 丙氨酸：Ka = 1.08 ± 0.40 h-1；Ke = 0.11 ± 0.06 h-1；BAa = 90% ± 11%。L - 丙氨酸：Ka = 1.75 ± 0.273 h-1；Ke = 0.02 ± 0.01 h-1；BA(a) = 99% ± 1%。在任何情况下均未出现高血糖、低血糖或糖尿。
三种底物从腹腔的吸收速率比从血浆的消除速率高近10倍。腹腔注射8小时后，绝对生物利用度几乎与静脉注射后一样高（即接近100%）。营养素的代谢似乎有助于腹腔吸收，因为L - 丙氨酸比D - 丙氨酸吸收得更好。这些结果表明，腹腔注射后，所研究的营养素在短时间内几乎完全被吸收，且无高血糖或新糖生成，因此表明其给药可能是腹膜透析患者喂养的一种可行方法。该模型可应用于其他化合物，如肽和二糖。
