Monosaccharide transport in the mammary gland of the intact lactating rat.
The Michaelis-Menten equation for the utilization of competing substrates was applied to the uptake of 2-deoxy[3H]glucose into the mammary gland of anaesthetized lactating rats. Intracellular water was calculated from total tissue water and sucrose space. Fed rats had a mean transport capacity of 2.2 mumol/min per g of tissue, giving an actual glucose transport in vivo of 1.1 mumol/min per g. Transport decreased by 90% on overnight starvation and returned to normal by 2 h of re-feeding. Similar changes were observed in the 1 min or 5 min transport of circulating 3-O-methylglucose. Transport of 3-O-methylglucose in starved rats was restored towards normal by insulin. In fed rats it increased between parturition and day 12 of lactation. The findings support the proposal that transport is a rate-limiting factor in the mammary utilization of carbohydrate.
D019325:3-O-Methylglucose; D000818:Animals; D001692:Biological Transport; D001786:Blood Glucose / Q000378:metabolism; D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000097:blood / Q000378:metabolism*; D005260:Female; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D007774:Lactation; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D008757:Methylglucosides / Q000378:metabolism*; D008759:Methylglycosides / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000378:metabolism
D001786:Blood Glucose; D003837:Deoxy Sugars; D007328:Insulin; D008757:Methylglucosides; D008759:Methylglycosides; D019325:3-O-Methylglucose; D003847:Deoxyglucose