Bioassay of insulin activity of pancreatic tissue in active and aestivated African lungfish, Protopterus annectens (Owen)

The insulin activity of the pancreatic tissues of free-swimming and aestivated African lungfish, P. annectens (Owen), was bioassayed against standard insulin in rabbits. The hepatic glycogen content and plasma glucose concentration in free-swimming and aestivated lungfish were also estimated. The liver glycogen content was 64·47 ± 6·32 and 7·19 ± 2·68 mgg⁻¹ net wt and the plasma glucose concentration was 37·62 ± 4·22 and 6·39 ± 1·29% in free-swimming and aestivated lungfish, respectively.
Extracts of pancreatic tissue of the lungfish produced a dose-dependent decrease in the plasma glucose concentration in rabbits. The magnitude of the decrease in plasma glucose concentration produced by extracts from aestivated specimens was significantly smaller (about 26%) compared to that produced by pancreatic extracts from free-swimming active lungfish (about 37%). The insulin activity of the pancreatic tissue was 0·82 ± 0·02 and 1·27 ± 0·25 iu mg⁻¹ dry pancreatic tissue weight in aestivated and free-swimming lungfish, respectively.