Glucose Absorption in the Cockroach

Abstract

1. The absorption of glucose from the gut of the cockroach has been studied by feeding starved insects with ¹⁴C-labelled glucose together with a dye, Amaranth. This dye is not absorbed from the lumen of the intestine and the net percentage glucose absorption has been calculated from the glucose/dye ratio in the various parts of the intestine. 2. Glucose absorption is largely confined to the mid-gut caeca. 3. The rate of crop emptying, which is an exponential function of time, is related to glucose concentration, so that the amount of fluid leaving the crop decreases with increasing concentration. This effect is determined by the osmotic pressure of the ingested fluid. 4. The total glucose absorption shows a linear relation with crop emptying, suggesting that crop emptying is the limiting process in glucose absorption in the cockroach.