1. The metabolic status of rats after end-to-side portacaval anastomosis and the extent to which this differs from sham-operated animals, both fed and pair-fed, was investigated.
2. The body weights of sham-operated pair-fed rats consistently matched the weights of animals with a portacaval anastomosis at different times after the operation, whereas liver weights were significantly reduced in anastomosed animals as compared with the other groups.
3. Plasma glucose, insulin and the irreversible disposal rates for plasma glucose (determined by single intravenous injection of [6-3H]glucose) were similarly and significantly reduced for animals with a portacaval anastomosis and sham-operated pair-fed animals as compared with sham-operated fed control rats.
4. In contrast, plasma free fatty acid levels were significantly higher in animals with a portacaval anastomosis as compared with both sham-operated fed control and sham-operated pair-fed groups of animals. Turnover of plasma free fatty acids was measured in vivo by single intravenous injection of [1-14C]palmitic acid. The raised levels of plasma free fatty acids in animals with a portacaval anastomosis were principally due to reduced clearance and not to an increase in lipolysis.
5. Plasma β-hydroxybutyrate levels were similar in sham-operated fed control rats and animals with a portacaval anastomosis. Pair-fed values were three to four times greater than sham-operated fed control values and after portacaval anastomosis and increased further after a period of 24 h fasting. Values obtained for anastomosed animals increased only marginally after 24 h fasting and were significantly lower than pair-fed-animal values.
6. The rat with an end-to-side portacaval anastomosis may be characterized to be in a metabolic state equivalent to a chronically underfed animal in terms of reduced glucose turnover and plasma insulin concentrations but differs in respect to plasma free fatty acid turnover and plasma β-hydroxybutyrate concentrations.