Ascaris suum: Continuous perfusion of the pseudocoelom and nutrient absorption

Abstract

A double-cannulation apparatus was constructed for continuous perfusion of the pseudocoelom of adult Ascaris suum while maintaining the intact parasite in a controlled incubation chamber. Peristaltic pumps maintained a constant flow rate of artificial perienteric fluid through the incubation chamber (1 ml/min) and through the parasite (100 μl/min). Based on protein determinations, perienteric fluid was removed from the pseudocoelom within 35 min of initiation of perfusion (3.5 ml). A nonabsorbable dye, Blue Dextran, was detected first in the perfusate 4 min (400 μl) after initiation of infusion into the pseudocoelom, and was maintained at a constant concentration in the perfusate by 8 min after initiation of dye infusion. Removal of the dye from the pseudocoelom was accomplished within 8 min (800 μl) after the cessation of dye infusion. Occlusion of the digestive tract had no effect ( P < 0.05) on the short-term (3 hr) absorption of 3H-labeled cholesterol, [ 14C]-3- o-methylglucose or [ 14C]glucose from the incubation medium into the perienteric cavity. Concentrations of isotopes in the pseudocoelom reached steady-state levels within 60 min of the initiation of incubation, but remained low (>0.5%) when compared to medium concentration. Similarly, the time course of the accumulation of [ 14C]glucose into individual tissue components did not differ in intact worms with or without patent intestinal tracts. Thus, the cuticular/muscle tissue largely appears to be the primary route of absorption of cholesterol and glucose in adult A. suum. The cannulation and perfusion procedure for A. suum is an adaptable system for continual or intermittent measurements of internal physiological processes, in particular, the absorption and metabolism of nutrients. Furthermore, this system permits simple modification for “closed-loop” perfusion or internal delivery of select compounds.