Normal expression and inflammation-induced changes of Na and Na/K ATPase activity in spinal dorsal horn of the rat

Abstract

We tested whether that peripheral inflammation induces changes in the spinal dorsal horn ATPase activity. Adult Sprague–Dawley rats were anesthetized (thiobarbital), the left hind paw (inflammation group; n = 15) was immersed in water at 60 °C for 60 s, which induced a local inflammation. A control group ( n = 12) was tested with water at room temperature. After 60 min of peripheral inflammation left (LDH) or right lumbar dorsal horn (RDH) were processed for total, Na/K, Na and remanent ATPase activities (nM P i (mg protein) −1 min −1). In control animals isoenzymatic activities were: Na (31.2%); Na/K (20.6%) and remanent (48.2%) from total ATPase activity. No LDH-RDH asymmetry was found. The inflammation group presented an ipsilateral increase of total ATPase activity in LDH ( X ± S.E.M.; 4798.9 ± 601) over the RDH (3982.2 ± 451; Δ + 817; P < 0.05). This is due to an increase in Na ATPase activity (1609.3 ± 297) over RDH (1164.2 ± 166; Δ + 445; P < 0.05). ATPase activities were increased in LDH from inflamed over the control group as follows: total (4798.9 ± 601; Δ + 840; P < 0.05), Na/K (1298.1 ± 301; Δ + 483; P < 0.05) and Na (1609.3 ± 297; Δ + 373; P < 0.05). These increased ATPase activities, induced in a short time, can be considered a functional marker of nociceptive neuronal activity.