Amino acid and glucose uptake by the isolated perfused guinea-pig mammary gland

• Published in: Experimental physiology 1974-04, Vol.59 (2), p.113-130
• Main Authors: Davis, S.R, Mepham, T.B
• Format: Article
• Language: English
• Subjects: Alanine - metabolism; Amino Acids - blood; Amino Acids - metabolism; animal science; Animals; Aspartic Acid - metabolism; Carbon Radioisotopes; Caseins - biosynthesis; Female; Glucose - metabolism; Glutamates - metabolism; Guinea Pigs; Lactation; livestock; Mammary Glands, Animal - metabolism; Organ Size; Perfusion; Pregnancy; Proline - metabolism; Serine - metabolism; Time Factors; zoology
• ISSN: 0033-5541; 0958-0670; 1469-445X
• DOI: 10.1113/expphysiol.1974.sp002251

A technique has been developed for perfusion of the isolated guinea-pig mammary gland. Perfusate flow rates per unit weight of tissue were similar to in vivo mammary blood flow in lactating rats and 2-3 times mammary blood flow in the lactating cow and goat. Amino acid uptake was measured by the arterio-venous difference technique. The uptake of ‘essential’ amino acids correlated with their relative content in guinea-pig milk protein, but uptake of ‘non-essential’ amino acids was insufficient to account for the predicted rate of protein synthesis. Uptake of most amino acids was dependent on the rate of supply of exogenous substrates. Glucose uptake was variable but mean uptake during perfusion correlated with the rate of substrate infusion and gland weight. After addition of [U- 14 C]glucose to the perfusate in one experiment, alanine, serine, glutamic acid, aspartic acid and proline residues in milk casein became significantly labelled. The maintenance of high perfusate flow rates was found to depend on the attention paid to filtration of the perfusate, but the rate of amino acid uptake was probably dependent on the availability of tryptophan.