IN VIVO INTESTINAL ABSORPTION OF SUGAR IN THE TOADFISH (MARINE TELEOST, OPSANUS TAU)

¹ Marine Biological Laboratory, Woods Hole, Massachusetts 02543 and Department of Physiology, Rutgers University, New Brunswick, New Jersey 08903

1. A technique for investigation of nutrient absorption in vivo in the intestine of free-swimming fish is described.

2. Glucose absorption occurs primarily in the upper third of toadfish intestine and is linear with time.

3. Anesthetized (MS-222) and free-swimming toadfish were similar with respect to intestinal absorption of glucose.

4. The absorption process exhibited saturation kinetics, conforming to the Michaelis-Menten equation. It is inhibited by phloridzin.

5. Active transport of glucose was demonstrated by the fact that absorption continues after the glucose concentration of the intestinal lumen has fallen below that of intestinal tissue and blood.

6. Difference in the in vivo and in vitro approaches to the study of intestinal transport and the significance of the observed kinetic parameters are discussed.