HEMOLYMPH FLOW DISTRIBUTION, CARDIAC-PERFORMANCE AND VENTILATION DURING MODERATE WALKING ACTIVITY IN CANCER-MAGISTER (DANA) (DECAPODA, CRUSTACEA)

Adult male Cancer magister (Dana) were equipped with pulsed-Doppler fl owmeters and pressure transducers for simultaneous measurement of hear t and ventilation frequencies, haemolymph flow through each of the maj or arterial systems and cardiac output and for calculation of stroke v olume, Each variable was measured at rest and during two consecutive p eriods of moderate treadmill walking activity and recovery. During act ivity, haemolymph flow through the sternal and anterolateral arteries increased, while flow through the hepatic arterial system decreased. T his resulted in a redistribution of haemolymph flow in which a proport ion of cardiac output was shifted from the anterior, posterior and hep atic arterial systems to the sternal arterial system, The relative pro portion of the cardiac output flowing through the anterolateral artery remained constant, This indicated that oxygen supply was shifted away from the digestive system to the muscles of the walking legs and the respiratory system, Cardiac output, heart rate and stroke volume all i ncreased in response to activity, The increase in cardiac output is th e result of a large increase in stroke volume and a small increase in heart rate. A doubling of ventilation rate also occurred during activi ty, Both the circulatory and ventilatory systems were restored to pre- activity values by 60 min of recovery.