Analysis of corrinoids in ovine tissues.
Corrinoids from various ovine tissue samples (liver, blood, small intestinal fluid and faeces) were analysed using a combination of high-performance liquid chromatography (HPLC) and a radioisotope dilution assay (RIDA) to estimate the distribution of corrinoids--the cobalamins hydroxocobalamin (OH-cbl), methylcobalamin (me-cbl) and 5'-deoxyadenosylcobalamin (ado-cbl), and cobalamin analogues--in these tissues. Samples were taken from either cobalt-deficient or cobalt-replete ewes, and ruminant and pre-ruminant lambs. In liver, ado-cbl predominated, followed by analogues, OH-cbl and me-cbl. Supplementation with either cobalt (ruminant) or vitamin B12 injections (pre-ruminant) increased the amount of ado-cbl and decreased analogues. In blood, OH-cbl predominated, followed by ado-cbl, analogues and me-cbl, respectively. In small intestinal fluid, the distribution from largest to smallest percentage was analogues, ado-cbl, OH-cbl and me-cbl. In faeces, analogues constituted the greatest proportion, followed by OH-cbl, ado-cbl and me-cbl, respectively. Owing to the small sample sizes only cautionary interpretations can be made. In contrast to humans, where me-cbl constitutes the highest proportion of corrinoids in plasma and ado-cbl in the liver, in sheep the amount of ado-cbl was consistently higher than me-cbl in all tissues. This may be due to the higher metabolic need of sheep for ado-cbl due to gluconeogenesis. Analogues and OH-cbl were found in each tissue, contrary to previous postulations. The much higher amount of vitamin B12 in small intestinal fluid compared with faeces indicates that a large proportion of the vitamin is absorbed by the gastro-intestinal tract.
Kelly
R J
RJ
Keratec Limited, Keratec Building, 1375 Springs Road, Lincoln, Canterbury 8152, Private Bag 4749, Christchurch, New Zealand.
Gruner
T M
TM
Furlong
J M
JM
Sykes
A R
AR
D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003035:Cobalt / Q000172:deficiency / Q000502:physiology; D003038:Cobamides / Q000032:analysis; D045728:Corrinoids / Q000032:analysis*; D005243:Feces / Q000737:chemistry; D005260:Female; D005766:Gastrointestinal Contents / Q000737:chemistry; D006801:Humans; D006879:Hydroxocobalamin / Q000032:analysis; D007421:Intestine, Small / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D011865:Radioisotope Dilution Technique; D012756:Sheep; D014805:Vitamin B 12 / Q000031:analogs & derivatives / Q000032:analysis
D003038:Cobamides; D045728:Corrinoids; D003035:Cobalt; C019476:mecobalamin; C000913:cobamamide; D014805:Vitamin B 12; D006879:Hydroxocobalamin