The effect of flight on the composition of haemolymph in the cockroach, Periplaneta americana

Abstract

The composition of the haemolymph in Periplaneta americana is markedly altered during the 6 h following a 10-min flight. Normal resting conditions are not re-established for at least 24 h. The haemolymph volume increases 30% between 1 and 6 h after flight while the concentration of Na +, remains constant. Within 2 min after the beginning of flight there is a significant increase in the concentration of K + followed by an increase in Ca 2+ and Mg 2+ at the time flight is terminated. The increase in volume of the haemolymph is accompanied by a 25% decrease in osmolarity. Twenty-four hours after flight both haemolymph volume and osmolarity are re-established at the pre-flight values. During the return of fluid volume and osmolarity to normal levels, the ion concentrations, with the possible exception of Na +, are kept constant. The concentration of trehalose increases 10% during the first 2 min of flight, then decreases to the resting level within 5 min after flight ceases. Twenty minutes after flight the concentration of trehalose rises again, to 35% above the resting level where it remains for at least a day. At 1 day after flight the total trehalose in the haemolymph pool has returned nearly to the pre-flight level.