Intestinal absorption of cholesterol, transport in the haemolymph, and incorporation into the fat body and Malpighian tubules of the larval dragonfly Aeshna cyanea.

Doses of 1.5 mumol cholesteryl oleate ingested by Aeshna cyanea larvae were partially hydrolysed in the intestinal lumen and the liberated oleic acid absorbed, while free cholesterol and unhydrolysed cholesteryl oleate were eliminated in the faeces. Ingestion of [4-14C]cholesterol dissolved in olive oil revealed that the larvae also absorbed free cholesterol, the minor part of which (up to 12%) was esterified in the midgut epithelium. Absorption and esterification were markedly enhanced when the same dose of labelled cholesterol was administered in 20% aqueous bovine serum albumin. Radioactivity was rather slowly released into the haemolymph where it was nearly exclusively associated with free cholesterol apart from traces of labelled cholesteryl ester which maximally amounted to 2.9% after 15 days. In the fat body labelled cholesteryl ester maximally amounted to 65% after 15 days, while in the triacylglycerol-storing Malpighian tubules it remained below 1% at all time periods investigated.