TOXICITY OF SEA WATER IN MAMMALS

Abstract

The lethal dose of sea water or of isosmotic NaCl soln. for 50% of rats, mice, and guinea pigs given the fluid by single intraperit. injn. is 16[plus or minus]2 (S.D.) % of body wt. The LD50 of [image] sucrose soln. for these species under same conditions is less than 1/2 LD50 of equisomolar salt solns. The LD50 of sea water by stomach tube in rats, given in divided doses at 30 min. intervals, is essentially the same as by intraperit. injn. More gradual admn. increases the LD50. The lethal Cl- concn. of plasma is the same for all routes of admn. (170 m eq./l. or greater). Dogs and seals (Phoca vitulina) retain more sea water by stomach if it is given in repeated small doses (0.33% of body wt.) than if given in a single large dose (3.3% of body wt.). Vomiting of sea water is due to gastric irritation, not merely to distention by fluid. The total dose of intraven. sea water required to kill seals varies with the infusion rate, but is approx. 4-9 % of body wt. Seals seem to be no more resistant to the effects of sea water than are other mammals; they do not excrete its salts any more concentratedly in urine. Sea water may kill animals through cellular dehydration, while extracellular fluid vol. is increased. Urea solns. probably kill without producing cellular dehydration. The central nervous system is believed most susceptible to tissue damage by sea water. The lethal dose of sea water for mammals is decreased by previous shortage of body water. Rats can be temporarily rendered more resistant to ordinarily lethal doses of sea water by repeated admn. of sub-lethal doses (adaptation).