Water Shift in the Muscle of Adrenalectomized Rats. ∗

Abstract

Animals with adrenal insufficiency suffer disturbances in ability to regulate the water and electrolyte content of their tissues and plasma. Increase has been reported in the water content of muscle, liver, and skin, 1 , 2 , 3 and decrease in the plasma volume. 4 , 5 , 6 , 7 The adrenalectomized animal cannot shift water as readily under stresses as does the normal animal. 1 The excretion of water is less, and of chlorides more 2 ; there is a change in the electrolyte content of the plasma, 8 and a disturbance in electrolyte balance. 9

Viale and Bruno 5 suggested that the changes in water content of tissues and plasma might be due to an increase in permeability. The present study was undertaken to determine whether any evidence of a change in permeability could be found in the tissues of animals suffering from adrenal insufficiency. The first series of experiments have dealt with the swelling and shrinking of tissues from normal and from adrenalectomized rats in balanced solutions of varying strengths. According to Gellhorn, 10 a close parallelism frequently exists between imbibition and permeability.

Muscles of normal and adrenalectomized albino rats weighing about 150 gm. were employed in this study. Adrenalectomized animals were used 4 to 7 days after the operation; only those animals giving evidence (loss of weight) of adrenal insufficiency were used. Animals obviously moribund were discarded. Under ether anesthesia, the m. extensor digitorum longus was dissected out, quickly weighed in a glass-stoppered weighing vial, then placed in aerated balanced salt solution at a temperature of 37.5° C, and with a pH of about 7.3. At definite time intervals, the muscle was lifted out, quickly dried on filter paper, weighed, and returned to the solution.

Fig. 1 shows the results obtained by such a procedure in a hypotonic solution (73 parts Locke's solution∗ to 27 parts distilled water). Muscles from adrenalectomized animals imbibe water considerably faster than those from normal animals; the maximum water uptake is about the same in either case, but is reached much sooner in the case of muscles from the adrenalectomized rats.