Plasma retinol transport and clearance in hypervitaminosis A.

Abstract

Effects of mild and severe hypervitaminosis A on retinol transport and clearance were studied in mature ewes. Excessive vitamin A intake was assoicated with high concentrations of vitamin A in plasma and liver, with elevated serum enzymes, with decreased feed consumption and packed cell volume, and with epithelial hyperplasia. Retinol transport in plasma increased 6- to 8-fold with excessive dietary vitamin A, was greater with mild hypervitaminosis A, and increased exponentially with vitamin A concentration in plasma. Clearance of retinol from plasma increased 2-fold with hypervitaminosis A, exhibited a greater response in the mild group, and increased linearly with vitamin A concentration in plasma. The relationship of clearance to vitamin A concentration in liver was described best by a power function. Retinol clearance represents a mechanism to maintain vitamin A concentration in plasma and may be most effective below vitamin A concentrations of 135 microgram/dl plasma. With severe hypervitaminosis A, massive vitamin A accumulates in liver leading to hepatic dysfunction and a resultant decrease in retinol clearance from plasma.

• Authors: S Donoghue, D S Kronfeld, C F Ramberg Jr
• Journal: Journal of dairy science (J Dairy Sci) Vol. 62 Issue 2 Pg. 326-32 (Feb 1979) ISSN: 0022-0302 [Print] United States
• PMID: 457982 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Vitamin A
• Aspartate Aminotransferases
• Alanine Transaminase
• Alkaline Phosphatase

Topics

• Alanine Transaminase (blood)
• Alkaline Phosphatase (blood)
• Animals
• Aspartate Aminotransferases (blood)
• Diet
• Dose-Response Relationship, Drug
• Female
• Hematocrit
• Liver (anatomy & histology, metabolism)
• Organ Size (drug effects)
• Sheep (metabolism)
• Vitamin A (adverse effects, blood, metabolism)