Physiological Saline Suitable for the Marine Isopod Crustacean Bathynomus doederleini

In order to establish the physiological saline suitable for the giant marine isopod Bathynomus doederleini, we analyzed ionic compositions, pH and osmotic pressure of the hemolymph. We made three test salines on the basis of ionic compositions of the hemolymph. Saline A contains surplus Cl− (89.5 mM over in comparison with the serum) and no SO42−. Saline B contains surplus Cl− (71.4 mM over) and normal SO42−. Saline C contains normal Cl− and surplus SO42− (35.7 mM over). We examined the effects of the test solutions and other salines on activities of isolated hearts. The heart in the salines continued to beat regularly more than 20 hr at 20°C. Heart rate in the test solutions was significantly higher (saline A: 66.5±5.1/min, n=8, saline B: 60.4±7.0/min, n=9, saline C: 67.9±8.4/min, n=8) than that in sea water (SW: 50.2±4.8/min, n=10) and was significantly lower than that in the saline for decapod which was originally designed by Pantin (Pantin's saline : 77.6 ±8.9 /min, n=8). Among the test salines, there were no significant differences in heart rate, systolic force and membrane potential of cardiac ganglionic neuron and myocardial cell. The standard physiological saline for Bathynomus was determined as follows (mM) ; Na+, 479.4; K+, 15.7; Ca2+, 14.6; Mg2+, 60.7; Cl−, 627.6; SO42−, 9.1; HEPES, 5; pH 7.9.