Cell Dehydration as a Mechanism of Ketamine Analgesic and Anesthetic Effects

Abstract

Effect of intraperitoneally (i.p.) injected sub-anesthetic (8×10-5-8×10-2 mg/g) and anesthetic (0.1 mg/g) doses of ketamine on rats' pain sensitivity and tissue hydration were studied. Determination of water content of tissue was performed by Adrian's traditional "tissue drying" experimental procedure. The number of functionally active receptors were determined by counting the number of [ 3 H]-ouabain molecules in tissues. Latent period of pain sensitivity was defined by means of hot plate test. Ketamine in sub-anesthetic doses had depressing effect on rats' latent period of pain sensitivity which was accompanied by tissues' dehydration. [ 3 H]-ouabain influence on brain tissues hydration was characterized by dose dependent three phases and this fact was accompanied by corresponding changes of ouabain receptors number in cell membrane. Ketamine in anesthetic dose had reversing effect on ouabain-induced cell hydration and it was different for each brain tissue. It was suggested that ketamine-induced cell dehydration leading to decrease of number of functional active proteins in membrane serves as a powerful mechanism through which an analgesic and anesthetic effects of ketamine on organisms were realized.