The phase relationships of glycogen and free fatty acids (FFA) in the digestive (midgut) gland, foot muscle and heart muscle of starved and aestivating giant African snails (Achatina achatina) were analysed by means of phase plane plots. Phase plane plots of glycogen against FFA content indicated that these metabolites were out of phase in the digestive gland but in phase in the foot muscle, whereas the plot for the heart muscle had a long axis parallel to the abscissa. Digestive gland glycogen was out of phase with foot muscle FFA and with heart muscle FFA. Phase plane plots of foot muscle glycogen digestive gland FFA had its long axis parallel to the abscissa, whereas the plot of foot muscle glycogen against heart muscle FFA showed that these metabolites were in phase. Heart muscle FFA was in phase with either foot muscle FFA or digestive gland FFA. Pyruvate kinase extracted from the foot muscle of starved and aestivating snails was very labile and behaved like the allosteric type by exhibiting co-operative interaction with respect to phosphoenolpyruvate, allosteric activation by fructose 1,6-diphosphate and inhibition by ATP. The oscillatory motions of glycogen and FFA are discussed in terms of anaerobic metabolism in aestivating snails.
Comparative biochemistry and physiology. B, Comparative biochemistry 02/1984; 78(2):461-6. DOI:10.1016/0305-0491(84)90059-2